Merge branch 'main' into use-shared-ssa-in-ir-dataflow

Docs: Updates for Ruby support

.codeqlmanifest.json

@@ -4,5 +4,7 @@
                "cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/tainted/qlpack.yml",
                "*/ql/examples/qlpack.yml",
                "*/upgrades/qlpack.yml",
+               "javascript/ql/experimental/adaptivethreatmodeling/lib/qlpack.yml",
+               "javascript/ql/experimental/adaptivethreatmodeling/src/qlpack.yml",
                "misc/legacy-support/*/qlpack.yml",
                "misc/suite-helpers/qlpack.yml" ] }

.github/workflows/codeql-analysis.yml

@@ -11,6 +11,8 @@ on:
       - 'rc/*'
     paths:
       - 'csharp/**'
+      - '.github/codeql/**'
+      - '.github/workflows/codeql-analysis.yml'
   schedule:
     - cron: '0 9 * * 1'
 
@@ -38,8 +40,8 @@ jobs:
 
     # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
     # If this step fails, then you should remove it and run the build manually (see below)
-    - name: Autobuild
-      uses: github/codeql-action/autobuild@main
+    #- name: Autobuild
+    #  uses: github/codeql-action/autobuild@main
 
     # ℹ️ Command-line programs to run using the OS shell.
     # 📚 https://git.io/JvXDl
@@ -48,9 +50,8 @@ jobs:
     #    and modify them (or add more) to build your code if your project
     #    uses a compiled language
 
-    #- run: |
-    #   make bootstrap
-    #   make release
+    - run: |
+       dotnet build csharp
 
     - name: Perform CodeQL Analysis
       uses: github/codeql-action/analyze@main

.github/workflows/csv-coverage-pr-artifacts.yml

@@ -6,6 +6,8 @@ on:
       - '.github/workflows/csv-coverage-pr-comment.yml'
       - '*/ql/src/**/*.ql'
       - '*/ql/src/**/*.qll'
+      - '*/ql/lib/**/*.ql'
+      - '*/ql/lib/**/*.qll'
       - 'misc/scripts/library-coverage/*.py'
       # input data files
       - '*/documentation/library-coverage/cwe-sink.csv'

.github/workflows/csv-coverage-update.yml

@@ -8,7 +8,7 @@ on:
 jobs:
   update:
     name: Update framework coverage report
-    if: github.event.repository.fork == false
+    if: github.repository == 'github/codeql'
     runs-on: ubuntu-latest
 
     steps:

.gitignore

@@ -24,3 +24,6 @@
 /codeql/
 
 csharp/extractor/Semmle.Extraction.CSharp.Driver/Properties/launchSettings.json
+
+# Avoid committing cached package components
+.codeql

README.md

@@ -4,8 +4,8 @@ This open source repository contains the standard CodeQL libraries and queries t
 
 ## How do I learn CodeQL and run queries?
 
-There is [extensive documentation](https://help.semmle.com/QL/learn-ql/) on getting started with writing CodeQL.
-You can use the [interactive query console](https://lgtm.com/help/lgtm/using-query-console) on LGTM.com or the [CodeQL for Visual Studio Code](https://help.semmle.com/codeql/codeql-for-vscode.html) extension to try out your queries on any open source project that's currently being analyzed.
+There is [extensive documentation](https://codeql.github.com/docs/) on getting started with writing CodeQL.
+You can use the [interactive query console](https://lgtm.com/help/lgtm/using-query-console) on LGTM.com or the [CodeQL for Visual Studio Code](https://codeql.github.com/docs/codeql-for-visual-studio-code/) extension to try out your queries on any open source project that's currently being analyzed.
 
 ## Contributing
 

config/identical-files.json

@@ -367,6 +367,7 @@
   ],
   "Inline Test Expectations": [
     "cpp/ql/test/TestUtilities/InlineExpectationsTest.qll",
+    "csharp/ql/test/TestUtilities/InlineExpectationsTest.qll",
     "java/ql/test/TestUtilities/InlineExpectationsTest.qll",
     "python/ql/test/TestUtilities/InlineExpectationsTest.qll"
   ],
@@ -461,5 +462,12 @@
   "ReDoS Polynomial Python/JS": [
     "javascript/ql/lib/semmle/javascript/security/performance/SuperlinearBackTracking.qll",
     "python/ql/lib/semmle/python/security/performance/SuperlinearBackTracking.qll"
+  ],
+  "CodeQL Tutorial": [
+    "cpp/ql/lib/tutorial.qll",
+    "csharp/ql/lib/tutorial.qll",
+    "java/ql/lib/tutorial.qll",
+    "javascript/ql/lib/tutorial.qll",
+    "python/ql/lib/tutorial.qll"
   ]
 }

cpp/change-notes/2021-06-10-cleartext-transmission.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* A new query (`cpp/cleartext-transmission`) has been added. This is similar to the `cpp/cleartext-storage-file`, `cpp/cleartext-storage-buffer` and `cpp/cleartext-storage-database` queries but looks for cases where sensitive information is most likely transmitted over a network.

cpp/change-notes/2021-06-22-sql-tainted.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The 'Uncontrolled data in SQL query' (cpp/sql-injection) query now supports the `libpqxx` library.

cpp/change-notes/2021-08-31-range-analysis-upper-bound.md

@@ -0,0 +1,4 @@
+lgtm,codescanning
+* The `SimpleRangeAnalysis` library includes information from the
+  immediate guard for determining the upper bound of a stack
+  variable for improved accuracy.

cpp/change-notes/2021-09-13-overflow-static.md

@@ -0,0 +1,4 @@
+lgtm,codescanning
+* The `memberMayBeVarSize` predicate considers more fields to be variable size.
+  As a result, the "Static buffer overflow" query (cpp/static-buffer-overflow)
+  produces fewer false positives.

cpp/change-notes/2021-09-27-command-line-injection.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The "Uncontrolled data used in OS command" (`cpp/command-line-injection`) query has been enhanced to reduce false positive results and its `@precision` increased to `high`

cpp/change-notes/2021-09-27-overflow-static.md

@@ -0,0 +1,3 @@
+lgtm,codescanning
+* Increase precision to high for the "Static buffer overflow" query
+  (`cpp/static-buffer-overflow`). This means the query is run and displayed by default on Code Scanning and LGTM.

cpp/change-notes/2021-10-01-improper-null-termination.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Several improvements made to the `NullTermination.qll` library and the 'Potential improper null termination' (cpp/improper-null-termination). These changes reduce the number of false positive results for this query and related query 'User-controlled data may not be null terminated' (cpp/user-controlled-null-termination-tainted).

cpp/change-notes/2021-10-07-extraction-errors.md

@@ -0,0 +1,3 @@
+codescanning
+* Problems with extraction that in most cases won't break the analysis in a significant way are now reported as warnings rather than errors.
+* The failed extractor invocations query now has severity `error`.

cpp/ql/lib/experimental/semmle/code/cpp/security/PrivateCleartextWrite.qll

@@ -52,11 +52,8 @@ module PrivateCleartextWrite {
 
   class WriteSink extends Sink {
     WriteSink() {
-      exists(FileWrite f, BufferWrite b |
-        this.asExpr() = f.getASource()
-        or
-        this.asExpr() = b.getAChild()
-      )
+      this.asExpr() = any(FileWrite f).getASource() or
+      this.asExpr() = any(BufferWrite b).getAChild()
     }
   }
 }

cpp/ql/lib/experimental/semmle/code/cpp/security/PrivateData.qll

@@ -13,26 +13,25 @@ import cpp
 
 /** A string for `match` that identifies strings that look like they represent private data. */
 private string privateNames() {
-  // Inspired by the list on https://cwe.mitre.org/data/definitions/359.html
-  // Government identifiers, such as Social Security Numbers
-  result = "%social%security%number%" or
-  // Contact information, such as home addresses and telephone numbers
-  result = "%postcode%" or
-  result = "%zipcode%" or
-  // result = "%telephone%" or
-  // Geographic location - where the user is (or was)
-  result = "%latitude%" or
-  result = "%longitude%" or
-  // Financial data - such as credit card numbers, salary, bank accounts, and debts
-  result = "%creditcard%" or
-  result = "%salary%" or
-  result = "%bankaccount%" or
-  // Communications - e-mail addresses, private e-mail messages, SMS text messages, chat logs, etc.
-  // result = "%email%" or
-  // result = "%mobile%" or
-  result = "%employer%" or
-  // Health - medical conditions, insurance status, prescription records
-  result = "%medical%"
+  result =
+    [
+      // Inspired by the list on https://cwe.mitre.org/data/definitions/359.html
+      // Government identifiers, such as Social Security Numbers
+      "%social%security%number%",
+      // Contact information, such as home addresses and telephone numbers
+      "%postcode%", "%zipcode%",
+      // result = "%telephone%" or
+      // Geographic location - where the user is (or was)
+      "%latitude%", "%longitude%",
+      // Financial data - such as credit card numbers, salary, bank accounts, and debts
+      "%creditcard%", "%salary%", "%bankaccount%",
+      // Communications - e-mail addresses, private e-mail messages, SMS text messages, chat logs, etc.
+      // result = "%email%" or
+      // result = "%mobile%" or
+      "%employer%",
+      // Health - medical conditions, insurance status, prescription records
+      "%medical%"
+    ]
 }
 
 /** An expression that might contain private data. */

cpp/ql/lib/external/ExternalArtifact.qll

@@ -15,7 +15,7 @@ class ExternalData extends @externalDataElement {
    * Gets the path of the file this data was loaded from, with its
    * extension replaced by `.ql`.
    */
-  string getQueryPath() { result = getDataPath().regexpReplaceAll("\\.[^.]*$", ".ql") }
+  string getQueryPath() { result = this.getDataPath().regexpReplaceAll("\\.[^.]*$", ".ql") }
 
   /** Gets the number of fields in this data item. */
   int getNumFields() { result = 1 + max(int i | externalData(this, _, i, _) | i) }
@@ -24,22 +24,22 @@ class ExternalData extends @externalDataElement {
   string getField(int i) { externalData(this, _, i, result) }
 
   /** Gets the integer value of the `i`th field of this data item. */
-  int getFieldAsInt(int i) { result = getField(i).toInt() }
+  int getFieldAsInt(int i) { result = this.getField(i).toInt() }
 
   /** Gets the floating-point value of the `i`th field of this data item. */
-  float getFieldAsFloat(int i) { result = getField(i).toFloat() }
+  float getFieldAsFloat(int i) { result = this.getField(i).toFloat() }
 
   /** Gets the value of the `i`th field of this data item, interpreted as a date. */
-  date getFieldAsDate(int i) { result = getField(i).toDate() }
+  date getFieldAsDate(int i) { result = this.getField(i).toDate() }
 
   /** Gets a textual representation of this data item. */
-  string toString() { result = getQueryPath() + ": " + buildTupleString(0) }
+  string toString() { result = this.getQueryPath() + ": " + this.buildTupleString(0) }
 
   /** Gets a textual representation of this data item, starting with the `n`th field. */
   private string buildTupleString(int n) {
-    n = getNumFields() - 1 and result = getField(n)
+    n = this.getNumFields() - 1 and result = this.getField(n)
     or
-    n < getNumFields() - 1 and result = getField(n) + "," + buildTupleString(n + 1)
+    n < this.getNumFields() - 1 and result = this.getField(n) + "," + this.buildTupleString(n + 1)
   }
 }
 
@@ -53,8 +53,8 @@ class DefectExternalData extends ExternalData {
   }
 
   /** Gets the URL associated with this data item. */
-  string getURL() { result = getField(0) }
+  string getURL() { result = this.getField(0) }
 
   /** Gets the message associated with this data item. */
-  string getMessage() { result = getField(1) }
+  string getMessage() { result = this.getField(1) }
 }

cpp/ql/lib/semmle/code/cpp/Class.qll

@@ -269,13 +269,13 @@ class Class extends UserType {
    * DEPRECATED: name changed to `hasImplicitCopyConstructor` to reflect that
    * `= default` members are no longer included.
    */
-  deprecated predicate hasGeneratedCopyConstructor() { hasImplicitCopyConstructor() }
+  deprecated predicate hasGeneratedCopyConstructor() { this.hasImplicitCopyConstructor() }
 
   /**
    * DEPRECATED: name changed to `hasImplicitCopyAssignmentOperator` to
    * reflect that `= default` members are no longer included.
    */
-  deprecated predicate hasGeneratedCopyAssignmentOperator() { hasImplicitCopyConstructor() }
+  deprecated predicate hasGeneratedCopyAssignmentOperator() { this.hasImplicitCopyConstructor() }
 
   /**
    * Holds if this class, struct or union has an implicitly-declared copy
@@ -487,7 +487,7 @@ class Class extends UserType {
     exists(ClassDerivation cd |
       // Add the offset of the direct base class and the offset of `baseClass`
       // within that direct base class.
-      cd = getADerivation() and
+      cd = this.getADerivation() and
       result = cd.getBaseClass().getANonVirtualBaseClassByteOffset(baseClass) + cd.getByteOffset()
     )
   }
@@ -502,12 +502,12 @@ class Class extends UserType {
    */
   int getABaseClassByteOffset(Class baseClass) {
     // Handle the non-virtual case.
-    result = getANonVirtualBaseClassByteOffset(baseClass)
+    result = this.getANonVirtualBaseClassByteOffset(baseClass)
     or
     exists(Class virtualBaseClass, int virtualBaseOffset, int offsetFromVirtualBase |
       // Look for the base class as a non-virtual base of a direct or indirect
       // virtual base, adding the two offsets.
-      getVirtualBaseClassByteOffset(virtualBaseClass) = virtualBaseOffset and
+      this.getVirtualBaseClassByteOffset(virtualBaseClass) = virtualBaseOffset and
       offsetFromVirtualBase = virtualBaseClass.getANonVirtualBaseClassByteOffset(baseClass) and
       result = virtualBaseOffset + offsetFromVirtualBase
     )
@@ -623,11 +623,11 @@ class Class extends UserType {
    * inherits one).
    */
   predicate isPolymorphic() {
-    exists(MemberFunction f | f.getDeclaringType() = getABaseClass*() and f.isVirtual())
+    exists(MemberFunction f | f.getDeclaringType() = this.getABaseClass*() and f.isVirtual())
   }
 
   override predicate involvesTemplateParameter() {
-    getATemplateArgument().(Type).involvesTemplateParameter()
+    this.getATemplateArgument().(Type).involvesTemplateParameter()
   }
 
   /** Holds if this class, struct or union was declared 'final'. */
@@ -765,7 +765,7 @@ class ClassDerivation extends Locatable, @derivation {
    * };
    * ```
    */
-  Class getBaseClass() { result = getBaseType().getUnderlyingType() }
+  Class getBaseClass() { result = this.getBaseType().getUnderlyingType() }
 
   override string getAPrimaryQlClass() { result = "ClassDerivation" }
 
@@ -818,7 +818,7 @@ class ClassDerivation extends Locatable, @derivation {
   predicate hasSpecifier(string s) { this.getASpecifier().hasName(s) }
 
   /** Holds if the derivation is for a virtual base class. */
-  predicate isVirtual() { hasSpecifier("virtual") }
+  predicate isVirtual() { this.hasSpecifier("virtual") }
 
   /** Gets the location of the derivation. */
   override Location getLocation() { derivations(underlyingElement(this), _, _, _, result) }
@@ -846,7 +846,7 @@ class ClassDerivation extends Locatable, @derivation {
  * ```
  */
 class LocalClass extends Class {
-  LocalClass() { isLocal() }
+  LocalClass() { this.isLocal() }
 
   override string getAPrimaryQlClass() { not this instanceof LocalStruct and result = "LocalClass" }
 
@@ -989,9 +989,9 @@ class ClassTemplateSpecialization extends Class {
   TemplateClass getPrimaryTemplate() {
     // Ignoring template arguments, the primary template has the same name
     // as each of its specializations.
-    result.getSimpleName() = getSimpleName() and
+    result.getSimpleName() = this.getSimpleName() and
     // It is in the same namespace as its specializations.
-    result.getNamespace() = getNamespace() and
+    result.getNamespace() = this.getNamespace() and
     // It is distinguished by the fact that each of its template arguments
     // is a distinct template parameter.
     count(TemplateParameter tp | tp = result.getATemplateArgument()) =
@@ -1108,7 +1108,7 @@ deprecated class Interface extends Class {
  * ```
  */
 class VirtualClassDerivation extends ClassDerivation {
-  VirtualClassDerivation() { hasSpecifier("virtual") }
+  VirtualClassDerivation() { this.hasSpecifier("virtual") }
 
   override string getAPrimaryQlClass() { result = "VirtualClassDerivation" }
 }
@@ -1136,7 +1136,7 @@ class VirtualBaseClass extends Class {
   VirtualClassDerivation getAVirtualDerivation() { result.getBaseClass() = this }
 
   /** A class/struct that is derived from this one using virtual inheritance. */
-  Class getAVirtuallyDerivedClass() { result = getAVirtualDerivation().getDerivedClass() }
+  Class getAVirtuallyDerivedClass() { result = this.getAVirtualDerivation().getDerivedClass() }
 }
 
 /**
@@ -1155,7 +1155,7 @@ class ProxyClass extends UserType {
   override string getAPrimaryQlClass() { result = "ProxyClass" }
 
   /** Gets the location of the proxy class. */
-  override Location getLocation() { result = getTemplateParameter().getDefinitionLocation() }
+  override Location getLocation() { result = this.getTemplateParameter().getDefinitionLocation() }
 
   /** Gets the template parameter for which this is the proxy class. */
   TemplateParameter getTemplateParameter() {

cpp/ql/lib/semmle/code/cpp/Declaration.qll

@@ -184,7 +184,7 @@ class Declaration extends Locatable, @declaration {
   predicate hasDefinition() { exists(this.getDefinition()) }
 
   /** DEPRECATED: Use `hasDefinition` instead. */
-  predicate isDefined() { hasDefinition() }
+  predicate isDefined() { this.hasDefinition() }
 
   /** Gets the preferred location of this declaration, if any. */
   override Location getLocation() { none() }
@@ -209,7 +209,7 @@ class Declaration extends Locatable, @declaration {
   predicate isStatic() { this.hasSpecifier("static") }
 
   /** Holds if this declaration is a member of a class/struct/union. */
-  predicate isMember() { hasDeclaringType() }
+  predicate isMember() { this.hasDeclaringType() }
 
   /** Holds if this declaration is a member of a class/struct/union. */
   predicate hasDeclaringType() { exists(this.getDeclaringType()) }
@@ -226,14 +226,14 @@ class Declaration extends Locatable, @declaration {
    * When called on a template, this will return a template parameter type for
    * both typed and non-typed parameters.
    */
-  final Locatable getATemplateArgument() { result = getTemplateArgument(_) }
+  final Locatable getATemplateArgument() { result = this.getTemplateArgument(_) }
 
   /**
    * Gets a template argument used to instantiate this declaration from a template.
    * When called on a template, this will return a non-typed template
    * parameter value.
    */
-  final Locatable getATemplateArgumentKind() { result = getTemplateArgumentKind(_) }
+  final Locatable getATemplateArgumentKind() { result = this.getTemplateArgumentKind(_) }
 
   /**
    * Gets the `i`th template argument used to instantiate this declaration from a
@@ -252,9 +252,9 @@ class Declaration extends Locatable, @declaration {
    * `getTemplateArgument(1)` return `1`.
    */
   final Locatable getTemplateArgument(int index) {
-    if exists(getTemplateArgumentValue(index))
-    then result = getTemplateArgumentValue(index)
-    else result = getTemplateArgumentType(index)
+    if exists(this.getTemplateArgumentValue(index))
+    then result = this.getTemplateArgumentValue(index)
+    else result = this.getTemplateArgumentType(index)
   }
 
   /**
@@ -275,14 +275,13 @@ class Declaration extends Locatable, @declaration {
    * `getTemplateArgumentKind(0)`.
    */
   final Locatable getTemplateArgumentKind(int index) {
-    if exists(getTemplateArgumentValue(index))
-    then result = getTemplateArgumentType(index)
-    else none()
+    exists(this.getTemplateArgumentValue(index)) and
+    result = this.getTemplateArgumentType(index)
   }
 
   /** Gets the number of template arguments for this declaration. */
   final int getNumberOfTemplateArguments() {
-    result = count(int i | exists(getTemplateArgument(i)))
+    result = count(int i | exists(this.getTemplateArgument(i)))
   }
 
   private Type getTemplateArgumentType(int index) {
@@ -328,9 +327,9 @@ class DeclarationEntry extends Locatable, TDeclarationEntry {
    * available), or the name declared by this entry otherwise.
    */
   string getCanonicalName() {
-    if getDeclaration().hasDefinition()
-    then result = getDeclaration().getDefinition().getName()
-    else result = getName()
+    if this.getDeclaration().hasDefinition()
+    then result = this.getDeclaration().getDefinition().getName()
+    else result = this.getName()
   }
 
   /**
@@ -371,18 +370,18 @@ class DeclarationEntry extends Locatable, TDeclarationEntry {
   /**
    * Holds if this declaration entry has a specifier with the given name.
    */
-  predicate hasSpecifier(string specifier) { getASpecifier() = specifier }
+  predicate hasSpecifier(string specifier) { this.getASpecifier() = specifier }
 
   /** Holds if this declaration entry is a definition. */
   predicate isDefinition() { none() } // overridden in subclasses
 
   override string toString() {
-    if isDefinition()
-    then result = "definition of " + getName()
+    if this.isDefinition()
+    then result = "definition of " + this.getName()
     else
-      if getName() = getCanonicalName()
-      then result = "declaration of " + getName()
-      else result = "declaration of " + getCanonicalName() + " as " + getName()
+      if this.getName() = this.getCanonicalName()
+      then result = "declaration of " + this.getName()
+      else result = "declaration of " + this.getCanonicalName() + " as " + this.getName()
   }
 }
 
@@ -581,7 +580,7 @@ private class DirectAccessHolder extends Element {
     // transitive closure with a restricted base case.
     this.thisCanAccessClassStep(base, derived)
     or
-    exists(Class between | thisCanAccessClassTrans(base, between) |
+    exists(Class between | this.thisCanAccessClassTrans(base, between) |
       isDirectPublicBaseOf(between, derived) or
       this.thisCanAccessClassStep(between, derived)
     )

cpp/ql/lib/semmle/code/cpp/Element.qll

@@ -61,7 +61,7 @@ class ElementBase extends @element {
   /**
    * Gets a comma-separated list of the names of the primary CodeQL classes to which this element belongs.
    */
-  final string getPrimaryQlClasses() { result = concat(getAPrimaryQlClass(), ",") }
+  final string getPrimaryQlClasses() { result = concat(this.getAPrimaryQlClass(), ",") }
 
   /**
    * Gets the name of a primary CodeQL class to which this element belongs.
@@ -206,9 +206,9 @@ class Element extends ElementBase {
   /** Gets the closest `Element` enclosing this one. */
   cached
   Element getEnclosingElement() {
-    result = getEnclosingElementPref()
+    result = this.getEnclosingElementPref()
     or
-    not exists(getEnclosingElementPref()) and
+    not exists(this.getEnclosingElementPref()) and
     (
       this = result.(Class).getAMember()
       or
@@ -281,7 +281,7 @@ private predicate isFromUninstantiatedTemplateRec(Element e, Element template) {
  * ```
  */
 class StaticAssert extends Locatable, @static_assert {
-  override string toString() { result = "static_assert(..., \"" + getMessage() + "\")" }
+  override string toString() { result = "static_assert(..., \"" + this.getMessage() + "\")" }
 
   /**
    * Gets the expression which this static assertion ensures is true.

cpp/ql/lib/semmle/code/cpp/Enum.qll

@@ -85,7 +85,7 @@ class Enum extends UserType, IntegralOrEnumType {
  * ```
  */
 class LocalEnum extends Enum {
-  LocalEnum() { isLocal() }
+  LocalEnum() { this.isLocal() }
 
   override string getAPrimaryQlClass() { result = "LocalEnum" }
 }

cpp/ql/lib/semmle/code/cpp/File.qll

@@ -38,7 +38,7 @@ class Container extends Locatable, @container {
    * DEPRECATED: Use `getLocation` instead.
    * Gets a URL representing the location of this container.
    *
-   * For more information see [Providing URLs](https://help.semmle.com/QL/learn-ql/ql/locations.html#providing-urls).
+   * For more information see [Providing URLs](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/#providing-urls).
    */
   deprecated string getURL() { none() } // overridden by subclasses
 
@@ -52,7 +52,7 @@ class Container extends Locatable, @container {
    */
   string getRelativePath() {
     exists(string absPath, string pref |
-      absPath = getAbsolutePath() and sourceLocationPrefix(pref)
+      absPath = this.getAbsolutePath() and sourceLocationPrefix(pref)
     |
       absPath = pref and result = ""
       or
@@ -79,7 +79,7 @@ class Container extends Locatable, @container {
    * </table>
    */
   string getBaseName() {
-    result = getAbsolutePath().regexpCapture(".*/(([^/]*?)(?:\\.([^.]*))?)", 1)
+    result = this.getAbsolutePath().regexpCapture(".*/(([^/]*?)(?:\\.([^.]*))?)", 1)
   }
 
   /**
@@ -105,7 +105,9 @@ class Container extends Locatable, @container {
    * <tr><td>"/tmp/x.tar.gz"</td><td>"gz"</td></tr>
    * </table>
    */
-  string getExtension() { result = getAbsolutePath().regexpCapture(".*/([^/]*?)(\\.([^.]*))?", 3) }
+  string getExtension() {
+    result = this.getAbsolutePath().regexpCapture(".*/([^/]*?)(\\.([^.]*))?", 3)
+  }
 
   /**
    * Gets the stem of this container, that is, the prefix of its base name up to
@@ -124,7 +126,9 @@ class Container extends Locatable, @container {
    * <tr><td>"/tmp/x.tar.gz"</td><td>"x.tar"</td></tr>
    * </table>
    */
-  string getStem() { result = getAbsolutePath().regexpCapture(".*/([^/]*?)(?:\\.([^.]*))?", 1) }
+  string getStem() {
+    result = this.getAbsolutePath().regexpCapture(".*/([^/]*?)(?:\\.([^.]*))?", 1)
+  }
 
   /** Gets the parent container of this file or folder, if any. */
   Container getParentContainer() {
@@ -135,20 +139,20 @@ class Container extends Locatable, @container {
   Container getAChildContainer() { this = result.getParentContainer() }
 
   /** Gets a file in this container. */
-  File getAFile() { result = getAChildContainer() }
+  File getAFile() { result = this.getAChildContainer() }
 
   /** Gets the file in this container that has the given `baseName`, if any. */
   File getFile(string baseName) {
-    result = getAFile() and
+    result = this.getAFile() and
     result.getBaseName() = baseName
   }
 
   /** Gets a sub-folder in this container. */
-  Folder getAFolder() { result = getAChildContainer() }
+  Folder getAFolder() { result = this.getAChildContainer() }
 
   /** Gets the sub-folder in this container that has the given `baseName`, if any. */
   Folder getFolder(string baseName) {
-    result = getAFolder() and
+    result = this.getAFolder() and
     result.getBaseName() = baseName
   }
 
@@ -157,7 +161,7 @@ class Container extends Locatable, @container {
    *
    * This is the absolute path of the container.
    */
-  override string toString() { result = getAbsolutePath() }
+  override string toString() { result = this.getAbsolutePath() }
 }
 
 /**
@@ -171,7 +175,7 @@ class Container extends Locatable, @container {
  * To get the full path, use `getAbsolutePath`.
  */
 class Folder extends Container, @folder {
-  override string getAbsolutePath() { folders(underlyingElement(this), result, _) }
+  override string getAbsolutePath() { folders(underlyingElement(this), result) }
 
   override Location getLocation() {
     result.getContainer() = this and
@@ -190,7 +194,7 @@ class Folder extends Container, @folder {
    * DEPRECATED: use `getAbsolutePath` instead.
    * Gets the name of this folder.
    */
-  deprecated string getName() { folders(underlyingElement(this), result, _) }
+  deprecated string getName() { folders(underlyingElement(this), result) }
 
   /**
    * DEPRECATED: use `getAbsolutePath` instead.
@@ -208,17 +212,7 @@ class Folder extends Container, @folder {
    * DEPRECATED: use `getBaseName` instead.
    * Gets the last part of the folder name.
    */
-  deprecated string getShortName() {
-    exists(string longnameRaw, string longname |
-      folders(underlyingElement(this), _, longnameRaw) and
-      longname = longnameRaw.replaceAll("\\", "/")
-    |
-      exists(int index |
-        result = longname.splitAt("/", index) and
-        not exists(longname.splitAt("/", index + 1))
-      )
-    )
-  }
+  deprecated string getShortName() { result = this.getBaseName() }
 
   /**
    * DEPRECATED: use `getParentContainer` instead.
@@ -242,7 +236,7 @@ class Folder extends Container, @folder {
  * `getStem` and `getExtension`. To get the full path, use `getAbsolutePath`.
  */
 class File extends Container, @file {
-  override string getAbsolutePath() { files(underlyingElement(this), result, _, _, _) }
+  override string getAbsolutePath() { files(underlyingElement(this), result) }
 
   override string toString() { result = Container.super.toString() }
 
@@ -336,7 +330,13 @@ class File extends Container, @file {
    * for example, for "file.tar.gz", this predicate will have the result
    * "tar.gz", while `getExtension` will have the result "gz".
    */
-  string getExtensions() { files(underlyingElement(this), _, _, result, _) }
+  string getExtensions() {
+    exists(string name, int firstDotPos |
+      name = this.getBaseName() and
+      firstDotPos = min([name.indexOf("."), name.length() - 1]) and
+      result = name.suffix(firstDotPos + 1)
+    )
+  }
 
   /**
    * Gets the short name of this file, that is, the prefix of its base name up
@@ -351,7 +351,16 @@ class File extends Container, @file {
    * for example, for "file.tar.gz", this predicate will have the result
    * "file", while `getStem` will have the result "file.tar".
    */
-  string getShortName() { files(underlyingElement(this), _, result, _, _) }
+  string getShortName() {
+    exists(string name, int firstDotPos |
+      name = this.getBaseName() and
+      firstDotPos = min([name.indexOf("."), name.length()]) and
+      result = name.prefix(firstDotPos)
+    )
+    or
+    this.getAbsolutePath() = "" and
+    result = ""
+  }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/Function.qll

@@ -43,26 +43,26 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    */
   string getFullSignature() {
     exists(string name, string templateArgs, string args |
-      result = name + templateArgs + args + " -> " + getType().toString() and
-      name = getQualifiedName() and
+      result = name + templateArgs + args + " -> " + this.getType().toString() and
+      name = this.getQualifiedName() and
       (
-        if exists(getATemplateArgument())
+        if exists(this.getATemplateArgument())
         then
           templateArgs =
             "<" +
               concat(int i |
-                exists(getTemplateArgument(i))
+                exists(this.getTemplateArgument(i))
               |
-                getTemplateArgument(i).toString(), ", " order by i
+                this.getTemplateArgument(i).toString(), ", " order by i
               ) + ">"
         else templateArgs = ""
       ) and
       args =
         "(" +
           concat(int i |
-            exists(getParameter(i))
+            exists(this.getParameter(i))
           |
-            getParameter(i).getType().toString(), ", " order by i
+            this.getParameter(i).getType().toString(), ", " order by i
           ) + ")"
     )
   }
@@ -70,7 +70,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
   /** Gets a specifier of this function. */
   override Specifier getASpecifier() {
     funspecifiers(underlyingElement(this), unresolveElement(result)) or
-    result.hasName(getADeclarationEntry().getASpecifier())
+    result.hasName(this.getADeclarationEntry().getASpecifier())
   }
 
   /** Gets an attribute of this function. */
@@ -149,7 +149,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * Holds if this function is declared with `__attribute__((naked))` or
    * `__declspec(naked)`.
    */
-  predicate isNaked() { getAnAttribute().hasName("naked") }
+  predicate isNaked() { this.getAnAttribute().hasName("naked") }
 
   /**
    * Holds if this function has a trailing return type.
@@ -172,7 +172,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * Gets the return type of this function after specifiers have been deeply
    * stripped and typedefs have been resolved.
    */
-  Type getUnspecifiedType() { result = getType().getUnspecifiedType() }
+  Type getUnspecifiedType() { result = this.getType().getUnspecifiedType() }
 
   /**
    * Gets the nth parameter of this function. There is no result for the
@@ -206,7 +206,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
   int getEffectiveNumberOfParameters() {
     // This method is overridden in `MemberFunction`, where the result is
     // adjusted to account for the implicit `this` parameter.
-    result = getNumberOfParameters()
+    result = this.getNumberOfParameters()
   }
 
   /**
@@ -216,7 +216,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * return `int p1, int p2`.
    */
   string getParameterString() {
-    result = concat(int i | | min(getParameter(i).getTypedName()), ", " order by i)
+    result = concat(int i | | min(this.getParameter(i).getTypedName()), ", " order by i)
   }
 
   /** Gets a call to this function. */
@@ -229,7 +229,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    */
   override FunctionDeclarationEntry getADeclarationEntry() {
     if fun_decls(_, underlyingElement(this), _, _, _)
-    then declEntry(result)
+    then this.declEntry(result)
     else
       exists(Function f |
         this.isConstructedFrom(f) and
@@ -250,7 +250,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * Gets the location of a `FunctionDeclarationEntry` corresponding to this
    * declaration.
    */
-  override Location getADeclarationLocation() { result = getADeclarationEntry().getLocation() }
+  override Location getADeclarationLocation() { result = this.getADeclarationEntry().getLocation() }
 
   /** Holds if this Function is a Template specialization. */
   predicate isSpecialization() {
@@ -265,14 +265,14 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * definition, if any.
    */
   override FunctionDeclarationEntry getDefinition() {
-    result = getADeclarationEntry() and
+    result = this.getADeclarationEntry() and
     result.isDefinition()
   }
 
   /** Gets the location of the definition, if any. */
   override Location getDefinitionLocation() {
-    if exists(getDefinition())
-    then result = getDefinition().getLocation()
+    if exists(this.getDefinition())
+    then result = this.getDefinition().getLocation()
     else exists(Function f | this.isConstructedFrom(f) and result = f.getDefinition().getLocation())
   }
 
@@ -281,7 +281,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * definition, if possible.)
    */
   override Location getLocation() {
-    if exists(getDefinition())
+    if exists(this.getDefinition())
     then result = this.getDefinitionLocation()
     else result = this.getADeclarationLocation()
   }
@@ -299,7 +299,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
   BlockStmt getBlock() { result.getParentScope() = this }
 
   /** Holds if this function has an entry point. */
-  predicate hasEntryPoint() { exists(getEntryPoint()) }
+  predicate hasEntryPoint() { exists(this.getEntryPoint()) }
 
   /**
    * Gets the first node in this function's control flow graph.
@@ -392,7 +392,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * Holds if this function has C linkage, as specified by one of its
    * declaration entries. For example: `extern "C" void foo();`.
    */
-  predicate hasCLinkage() { getADeclarationEntry().hasCLinkage() }
+  predicate hasCLinkage() { this.getADeclarationEntry().hasCLinkage() }
 
   /**
    * Holds if this function is constructed from `f` as a result
@@ -409,27 +409,27 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * several functions that are not linked together have been compiled. An
    * example would be a project with many 'main' functions.
    */
-  predicate isMultiplyDefined() { strictcount(getFile()) > 1 }
+  predicate isMultiplyDefined() { strictcount(this.getFile()) > 1 }
 
   /** Holds if this function is a varargs function. */
-  predicate isVarargs() { hasSpecifier("varargs") }
+  predicate isVarargs() { this.hasSpecifier("varargs") }
 
   /** Gets a type that is specified to be thrown by the function. */
-  Type getAThrownType() { result = getADeclarationEntry().getAThrownType() }
+  Type getAThrownType() { result = this.getADeclarationEntry().getAThrownType() }
 
   /**
    * Gets the `i`th type specified to be thrown by the function.
    */
-  Type getThrownType(int i) { result = getADeclarationEntry().getThrownType(i) }
+  Type getThrownType(int i) { result = this.getADeclarationEntry().getThrownType(i) }
 
   /** Holds if the function has an exception specification. */
-  predicate hasExceptionSpecification() { getADeclarationEntry().hasExceptionSpecification() }
+  predicate hasExceptionSpecification() { this.getADeclarationEntry().hasExceptionSpecification() }
 
   /** Holds if this function has a `throw()` exception specification. */
-  predicate isNoThrow() { getADeclarationEntry().isNoThrow() }
+  predicate isNoThrow() { this.getADeclarationEntry().isNoThrow() }
 
   /** Holds if this function has a `noexcept` exception specification. */
-  predicate isNoExcept() { getADeclarationEntry().isNoExcept() }
+  predicate isNoExcept() { this.getADeclarationEntry().isNoExcept() }
 
   /**
    * Gets a function that overloads this one.
@@ -539,7 +539,7 @@ private predicate candGetAnOverloadNonMember(string name, Namespace namespace, F
  */
 class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
   /** Gets the function which is being declared or defined. */
-  override Function getDeclaration() { result = getFunction() }
+  override Function getDeclaration() { result = this.getFunction() }
 
   override string getAPrimaryQlClass() { result = "FunctionDeclarationEntry" }
 
@@ -586,7 +586,7 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
    *   case, catch) plus the number of branching expressions (`?`, `&&`,
    *   `||`) plus one.
    */
-  int getCyclomaticComplexity() { result = 1 + cyclomaticComplexityBranches(getBlock()) }
+  int getCyclomaticComplexity() { result = 1 + cyclomaticComplexityBranches(this.getBlock()) }
 
   /**
    * If this is a function definition, get the block containing the
@@ -594,7 +594,7 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
    */
   BlockStmt getBlock() {
     this.isDefinition() and
-    result = getFunction().getBlock() and
+    result = this.getFunction().getBlock() and
     result.getFile() = this.getFile()
   }
 
@@ -604,7 +604,7 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
    */
   pragma[noopt]
   int getNumberOfLines() {
-    exists(BlockStmt b, Location l, int start, int end, int diff | b = getBlock() |
+    exists(BlockStmt b, Location l, int start, int end, int diff | b = this.getBlock() |
       l = b.getLocation() and
       start = l.getStartLine() and
       end = l.getEndLine() and
@@ -618,7 +618,7 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
    * declaration.
    */
   ParameterDeclarationEntry getAParameterDeclarationEntry() {
-    result = getParameterDeclarationEntry(_)
+    result = this.getParameterDeclarationEntry(_)
   }
 
   /**
@@ -639,7 +639,8 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
    * return 'int p1, int p2'.
    */
   string getParameterString() {
-    result = concat(int i | | min(getParameterDeclarationEntry(i).getTypedName()), ", " order by i)
+    result =
+      concat(int i | | min(this.getParameterDeclarationEntry(i).getTypedName()), ", " order by i)
   }
 
   /**
@@ -647,10 +648,10 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
    *
    *    `extern "C" void foo();`
    */
-  predicate hasCLinkage() { getASpecifier() = "c_linkage" }
+  predicate hasCLinkage() { this.getASpecifier() = "c_linkage" }
 
   /** Holds if this declaration entry has a void parameter list. */
-  predicate hasVoidParamList() { getASpecifier() = "void_param_list" }
+  predicate hasVoidParamList() { this.getASpecifier() = "void_param_list" }
 
   /** Holds if this declaration is also a definition of its function. */
   override predicate isDefinition() { fun_def(underlyingElement(this)) }
@@ -665,7 +666,7 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
   predicate isImplicit() { fun_implicit(underlyingElement(this)) }
 
   /** Gets a type that is specified to be thrown by the declared function. */
-  Type getAThrownType() { result = getThrownType(_) }
+  Type getAThrownType() { result = this.getThrownType(_) }
 
   /**
    * Gets the `i`th type specified to be thrown by the declared function
@@ -690,8 +691,8 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
   predicate hasExceptionSpecification() {
     fun_decl_throws(underlyingElement(this), _, _) or
     fun_decl_noexcept(underlyingElement(this), _) or
-    isNoThrow() or
-    isNoExcept()
+    this.isNoThrow() or
+    this.isNoExcept()
   }
 
   /**
@@ -763,7 +764,7 @@ class Operator extends Function {
  */
 class TemplateFunction extends Function {
   TemplateFunction() {
-    is_function_template(underlyingElement(this)) and exists(getATemplateArgument())
+    is_function_template(underlyingElement(this)) and exists(this.getATemplateArgument())
   }
 
   override string getAPrimaryQlClass() { result = "TemplateFunction" }

cpp/ql/lib/semmle/code/cpp/Include.qll

@@ -23,7 +23,7 @@ class Include extends PreprocessorDirective, @ppd_include {
    * Gets the token which occurs after `#include`, for example `"filename"`
    * or `<filename>`.
    */
-  string getIncludeText() { result = getHead() }
+  string getIncludeText() { result = this.getHead() }
 
   /** Gets the file directly included by this `#include`. */
   File getIncludedFile() { includes(underlyingElement(this), unresolveElement(result)) }
@@ -53,7 +53,7 @@ class Include extends PreprocessorDirective, @ppd_include {
  * ```
  */
 class IncludeNext extends Include, @ppd_include_next {
-  override string toString() { result = "#include_next " + getIncludeText() }
+  override string toString() { result = "#include_next " + this.getIncludeText() }
 }
 
 /**
@@ -65,5 +65,5 @@ class IncludeNext extends Include, @ppd_include_next {
  * ```
  */
 class Import extends Include, @ppd_objc_import {
-  override string toString() { result = "#import " + getIncludeText() }
+  override string toString() { result = "#import " + this.getIncludeText() }
 }

cpp/ql/lib/semmle/code/cpp/Initializer.qll

@@ -34,8 +34,8 @@ class Initializer extends ControlFlowNode, @initialiser {
   override predicate fromSource() { not this.getLocation() instanceof UnknownLocation }
 
   override string toString() {
-    if exists(getDeclaration())
-    then result = "initializer for " + max(getDeclaration().getName())
+    if exists(this.getDeclaration())
+    then result = "initializer for " + max(this.getDeclaration().getName())
     else result = "initializer"
   }
 

cpp/ql/lib/semmle/code/cpp/Location.qll

@@ -61,7 +61,7 @@ class Location extends @location {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -79,8 +79,8 @@ class Location extends @location {
 
   /** Holds if location `l` is completely contained within this one. */
   predicate subsumes(Location l) {
-    exists(File f | f = getFile() |
-      exists(int thisStart, int thisEnd | charLoc(f, thisStart, thisEnd) |
+    exists(File f | f = this.getFile() |
+      exists(int thisStart, int thisEnd | this.charLoc(f, thisStart, thisEnd) |
         exists(int lStart, int lEnd | l.charLoc(f, lStart, lEnd) |
           thisStart <= lStart and lEnd <= thisEnd
         )
@@ -97,10 +97,10 @@ class Location extends @location {
    * see `subsumes`.
    */
   predicate charLoc(File f, int start, int end) {
-    f = getFile() and
+    f = this.getFile() and
     exists(int maxCols | maxCols = maxCols(f) |
-      start = getStartLine() * maxCols + getStartColumn() and
-      end = getEndLine() * maxCols + getEndColumn()
+      start = this.getStartLine() * maxCols + this.getStartColumn() and
+      end = this.getEndLine() * maxCols + this.getEndColumn()
     )
   }
 }
@@ -144,7 +144,7 @@ class Locatable extends Element { }
  * expressions, one for statements and one for other program elements.
  */
 class UnknownLocation extends Location {
-  UnknownLocation() { getFile().getAbsolutePath() = "" }
+  UnknownLocation() { this.getFile().getAbsolutePath() = "" }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/Macro.qll

@@ -44,10 +44,10 @@ class Macro extends PreprocessorDirective, @ppd_define {
    * Gets the name of the macro.  For example, `MAX` in
    * `#define MAX(x,y) (((x)>(y))?(x):(y))`.
    */
-  string getName() { result = getHead().splitAt("(", 0) }
+  string getName() { result = this.getHead().splitAt("(", 0) }
 
   /** Holds if the macro has name `name`. */
-  predicate hasName(string name) { getName() = name }
+  predicate hasName(string name) { this.getName() = name }
 }
 
 /**
@@ -130,7 +130,7 @@ class MacroAccess extends Locatable, @macroinvocation {
   override string toString() { result = this.getMacro().getHead() }
 
   /** Gets the name of the accessed macro. */
-  string getMacroName() { result = getMacro().getName() }
+  string getMacroName() { result = this.getMacro().getName() }
 }
 
 /**
@@ -197,8 +197,8 @@ class MacroInvocation extends MacroAccess {
    * expression. In other cases, it may have multiple results or no results.
    */
   Expr getExpr() {
-    result = getAnExpandedElement() and
-    not result.getParent() = getAnExpandedElement() and
+    result = this.getAnExpandedElement() and
+    not result.getParent() = this.getAnExpandedElement() and
     not result instanceof Conversion
   }
 
@@ -208,8 +208,8 @@ class MacroInvocation extends MacroAccess {
    * element is not a statement (for example if it is an expression).
    */
   Stmt getStmt() {
-    result = getAnExpandedElement() and
-    not result.getParent() = getAnExpandedElement()
+    result = this.getAnExpandedElement() and
+    not result.getParent() = this.getAnExpandedElement()
   }
 
   /**
@@ -278,7 +278,7 @@ deprecated class MacroInvocationExpr extends Expr {
   MacroInvocation getInvocation() { result.getExpr() = this }
 
   /** Gets the name of the invoked macro. */
-  string getMacroName() { result = getInvocation().getMacroName() }
+  string getMacroName() { result = this.getInvocation().getMacroName() }
 }
 
 /**
@@ -298,7 +298,7 @@ deprecated class MacroInvocationStmt extends Stmt {
   MacroInvocation getInvocation() { result.getStmt() = this }
 
   /** Gets the name of the invoked macro. */
-  string getMacroName() { result = getInvocation().getMacroName() }
+  string getMacroName() { result = this.getInvocation().getMacroName() }
 }
 
 /** Holds if `l` is the location of a macro. */

cpp/ql/lib/semmle/code/cpp/MemberFunction.qll

@@ -36,7 +36,9 @@ class MemberFunction extends Function {
    * `this` parameter.
    */
   override int getEffectiveNumberOfParameters() {
-    if isStatic() then result = getNumberOfParameters() else result = getNumberOfParameters() + 1
+    if this.isStatic()
+    then result = this.getNumberOfParameters()
+    else result = this.getNumberOfParameters() + 1
   }
 
   /** Holds if this member is private. */
@@ -49,13 +51,13 @@ class MemberFunction extends Function {
   predicate isPublic() { this.hasSpecifier("public") }
 
   /** Holds if this declaration has the lvalue ref-qualifier */
-  predicate isLValueRefQualified() { hasSpecifier("&") }
+  predicate isLValueRefQualified() { this.hasSpecifier("&") }
 
   /** Holds if this declaration has the rvalue ref-qualifier */
-  predicate isRValueRefQualified() { hasSpecifier("&&") }
+  predicate isRValueRefQualified() { this.hasSpecifier("&&") }
 
   /** Holds if this declaration has a ref-qualifier */
-  predicate isRefQualified() { isLValueRefQualified() or isRValueRefQualified() }
+  predicate isRefQualified() { this.isLValueRefQualified() or this.isRValueRefQualified() }
 
   /** Holds if this function overrides that function. */
   predicate overrides(MemberFunction that) {
@@ -73,10 +75,10 @@ class MemberFunction extends Function {
    * class body.
    */
   FunctionDeclarationEntry getClassBodyDeclarationEntry() {
-    if strictcount(getADeclarationEntry()) = 1
-    then result = getDefinition()
+    if strictcount(this.getADeclarationEntry()) = 1
+    then result = this.getDefinition()
     else (
-      result = getADeclarationEntry() and result != getDefinition()
+      result = this.getADeclarationEntry() and result != this.getDefinition()
     )
   }
 
@@ -198,7 +200,7 @@ class Constructor extends MemberFunction {
    * compiler-generated action which initializes a base class or member
    * variable.
    */
-  ConstructorInit getAnInitializer() { result = getInitializer(_) }
+  ConstructorInit getAnInitializer() { result = this.getInitializer(_) }
 
   /**
    * Gets an entry in the constructor's initializer list, or a
@@ -220,8 +222,8 @@ class ImplicitConversionFunction extends MemberFunction {
     functions(underlyingElement(this), _, 4)
     or
     // ConversionConstructor (deprecated)
-    strictcount(Parameter p | p = getAParameter() and not p.hasInitializer()) = 1 and
-    not hasSpecifier("explicit")
+    strictcount(Parameter p | p = this.getAParameter() and not p.hasInitializer()) = 1 and
+    not this.hasSpecifier("explicit")
   }
 
   /** Gets the type this `ImplicitConversionFunction` takes as input. */
@@ -248,8 +250,8 @@ class ImplicitConversionFunction extends MemberFunction {
  */
 deprecated class ConversionConstructor extends Constructor, ImplicitConversionFunction {
   ConversionConstructor() {
-    strictcount(Parameter p | p = getAParameter() and not p.hasInitializer()) = 1 and
-    not hasSpecifier("explicit")
+    strictcount(Parameter p | p = this.getAParameter() and not p.hasInitializer()) = 1 and
+    not this.hasSpecifier("explicit")
   }
 
   override string getAPrimaryQlClass() {
@@ -301,15 +303,15 @@ class CopyConstructor extends Constructor {
     hasCopySignature(this) and
     (
       // The rest of the parameters all have default values
-      forall(int i | i > 0 and exists(getParameter(i)) | getParameter(i).hasInitializer())
+      forall(int i | i > 0 and exists(this.getParameter(i)) | this.getParameter(i).hasInitializer())
       or
       // or this is a template class, in which case the default values have
       // not been extracted even if they exist. In that case, we assume that
       // there are default values present since that is the most common case
       // in real-world code.
-      getDeclaringType() instanceof TemplateClass
+      this.getDeclaringType() instanceof TemplateClass
     ) and
-    not exists(getATemplateArgument())
+    not exists(this.getATemplateArgument())
   }
 
   override string getAPrimaryQlClass() { result = "CopyConstructor" }
@@ -325,8 +327,8 @@ class CopyConstructor extends Constructor {
     // type-checked for each template instantiation; if an argument in an
     // instantiation fails to type-check then the corresponding parameter has
     // no default argument in the instantiation.
-    getDeclaringType() instanceof TemplateClass and
-    getNumberOfParameters() > 1
+    this.getDeclaringType() instanceof TemplateClass and
+    this.getNumberOfParameters() > 1
   }
 }
 
@@ -358,15 +360,15 @@ class MoveConstructor extends Constructor {
     hasMoveSignature(this) and
     (
       // The rest of the parameters all have default values
-      forall(int i | i > 0 and exists(getParameter(i)) | getParameter(i).hasInitializer())
+      forall(int i | i > 0 and exists(this.getParameter(i)) | this.getParameter(i).hasInitializer())
       or
       // or this is a template class, in which case the default values have
       // not been extracted even if they exist. In that case, we assume that
       // there are default values present since that is the most common case
       // in real-world code.
-      getDeclaringType() instanceof TemplateClass
+      this.getDeclaringType() instanceof TemplateClass
     ) and
-    not exists(getATemplateArgument())
+    not exists(this.getATemplateArgument())
   }
 
   override string getAPrimaryQlClass() { result = "MoveConstructor" }
@@ -382,8 +384,8 @@ class MoveConstructor extends Constructor {
     // type-checked for each template instantiation; if an argument in an
     // instantiation fails to type-check then the corresponding parameter has
     // no default argument in the instantiation.
-    getDeclaringType() instanceof TemplateClass and
-    getNumberOfParameters() > 1
+    this.getDeclaringType() instanceof TemplateClass and
+    this.getNumberOfParameters() > 1
   }
 }
 
@@ -426,7 +428,7 @@ class Destructor extends MemberFunction {
    * Gets a compiler-generated action which destructs a base class or member
    * variable.
    */
-  DestructorDestruction getADestruction() { result = getDestruction(_) }
+  DestructorDestruction getADestruction() { result = this.getDestruction(_) }
 
   /**
    * Gets a compiler-generated action which destructs a base class or member
@@ -475,16 +477,16 @@ class ConversionOperator extends MemberFunction, ImplicitConversionFunction {
  */
 class CopyAssignmentOperator extends Operator {
   CopyAssignmentOperator() {
-    hasName("operator=") and
+    this.hasName("operator=") and
     (
       hasCopySignature(this)
       or
       // Unlike CopyConstructor, this member allows a non-reference
       // parameter.
-      getParameter(0).getUnspecifiedType() = getDeclaringType()
+      this.getParameter(0).getUnspecifiedType() = this.getDeclaringType()
     ) and
     not exists(this.getParameter(1)) and
-    not exists(getATemplateArgument())
+    not exists(this.getATemplateArgument())
   }
 
   override string getAPrimaryQlClass() { result = "CopyAssignmentOperator" }
@@ -507,10 +509,10 @@ class CopyAssignmentOperator extends Operator {
  */
 class MoveAssignmentOperator extends Operator {
   MoveAssignmentOperator() {
-    hasName("operator=") and
+    this.hasName("operator=") and
     hasMoveSignature(this) and
     not exists(this.getParameter(1)) and
-    not exists(getATemplateArgument())
+    not exists(this.getATemplateArgument())
   }
 
   override string getAPrimaryQlClass() { result = "MoveAssignmentOperator" }

cpp/ql/lib/semmle/code/cpp/Namespace.qll

@@ -38,8 +38,8 @@ class Namespace extends NameQualifyingElement, @namespace {
    * unless the namespace has exactly one declaration entry.
    */
   override Location getLocation() {
-    if strictcount(getADeclarationEntry()) = 1
-    then result = getADeclarationEntry().getLocation()
+    if strictcount(this.getADeclarationEntry()) = 1
+    then result = this.getADeclarationEntry().getLocation()
     else result instanceof UnknownDefaultLocation
   }
 
@@ -50,7 +50,7 @@ class Namespace extends NameQualifyingElement, @namespace {
   predicate hasName(string name) { name = this.getName() }
 
   /** Holds if this namespace is anonymous. */
-  predicate isAnonymous() { hasName("(unnamed namespace)") }
+  predicate isAnonymous() { this.hasName("(unnamed namespace)") }
 
   /** Gets the name of the parent namespace, if it exists. */
   private string getParentName() {
@@ -60,9 +60,9 @@ class Namespace extends NameQualifyingElement, @namespace {
 
   /** Gets the qualified name of this namespace. For example: `a::b`. */
   string getQualifiedName() {
-    if exists(getParentName())
-    then result = getParentNamespace().getQualifiedName() + "::" + getName()
-    else result = getName()
+    if exists(this.getParentName())
+    then result = this.getParentNamespace().getQualifiedName() + "::" + this.getName()
+    else result = this.getName()
   }
 
   /** Gets the parent namespace, if any. */
@@ -99,7 +99,7 @@ class Namespace extends NameQualifyingElement, @namespace {
   /** Gets a version of the `QualifiedName` that is more suitable for display purposes. */
   string getFriendlyName() { result = this.getQualifiedName() }
 
-  final override string toString() { result = getFriendlyName() }
+  final override string toString() { result = this.getFriendlyName() }
 
   /** Gets a declaration of (part of) this namespace. */
   NamespaceDeclarationEntry getADeclarationEntry() { result.getNamespace() = this }

cpp/ql/lib/semmle/code/cpp/Parameter.qll

@@ -40,12 +40,12 @@ class Parameter extends LocalScopeVariable, @parameter {
    */
   override string getName() {
     exists(VariableDeclarationEntry vde |
-      vde = getANamedDeclarationEntry() and result = vde.getName()
+      vde = this.getANamedDeclarationEntry() and result = vde.getName()
     |
-      vde.isDefinition() or not getANamedDeclarationEntry().isDefinition()
+      vde.isDefinition() or not this.getANamedDeclarationEntry().isDefinition()
     )
     or
-    not exists(getANamedDeclarationEntry()) and
+    not exists(this.getANamedDeclarationEntry()) and
     result = "(unnamed parameter " + this.getIndex().toString() + ")"
   }
 
@@ -58,8 +58,12 @@ class Parameter extends LocalScopeVariable, @parameter {
    */
   string getTypedName() {
     exists(string typeString, string nameString |
-      (if exists(getType().getName()) then typeString = getType().getName() else typeString = "") and
-      (if exists(getName()) then nameString = getName() else nameString = "") and
+      (
+        if exists(this.getType().getName())
+        then typeString = this.getType().getName()
+        else typeString = ""
+      ) and
+      (if exists(this.getName()) then nameString = this.getName() else nameString = "") and
       (
         if typeString != "" and nameString != ""
         then result = typeString + " " + nameString
@@ -69,7 +73,7 @@ class Parameter extends LocalScopeVariable, @parameter {
   }
 
   private VariableDeclarationEntry getANamedDeclarationEntry() {
-    result = getAnEffectiveDeclarationEntry() and result.getName() != ""
+    result = this.getAnEffectiveDeclarationEntry() and result.getName() != ""
   }
 
   /**
@@ -82,13 +86,13 @@ class Parameter extends LocalScopeVariable, @parameter {
    * own).
    */
   private VariableDeclarationEntry getAnEffectiveDeclarationEntry() {
-    if getFunction().isConstructedFrom(_)
+    if this.getFunction().isConstructedFrom(_)
     then
       exists(Function prototypeInstantiation |
-        prototypeInstantiation.getParameter(getIndex()) = result.getVariable() and
-        getFunction().isConstructedFrom(prototypeInstantiation)
+        prototypeInstantiation.getParameter(this.getIndex()) = result.getVariable() and
+        this.getFunction().isConstructedFrom(prototypeInstantiation)
       )
-    else result = getADeclarationEntry()
+    else result = this.getADeclarationEntry()
   }
 
   /**
@@ -114,7 +118,7 @@ class Parameter extends LocalScopeVariable, @parameter {
    * `getName()` is not "(unnamed parameter i)" (where `i` is the index
    * of the parameter).
    */
-  predicate isNamed() { exists(getANamedDeclarationEntry()) }
+  predicate isNamed() { exists(this.getANamedDeclarationEntry()) }
 
   /**
    * Gets the function to which this parameter belongs, if it is a function
@@ -157,9 +161,9 @@ class Parameter extends LocalScopeVariable, @parameter {
    */
   override Location getLocation() {
     exists(VariableDeclarationEntry vde |
-      vde = getAnEffectiveDeclarationEntry() and result = vde.getLocation()
+      vde = this.getAnEffectiveDeclarationEntry() and result = vde.getLocation()
     |
-      vde.isDefinition() or not getAnEffectiveDeclarationEntry().isDefinition()
+      vde.isDefinition() or not this.getAnEffectiveDeclarationEntry().isDefinition()
     )
   }
 }

cpp/ql/lib/semmle/code/cpp/Preprocessor.qll

@@ -29,8 +29,8 @@ class PreprocessorDirective extends Locatable, @preprocdirect {
   PreprocessorBranch getAGuard() {
     exists(PreprocessorEndif e, int line |
       result.getEndIf() = e and
-      e.getFile() = getFile() and
-      result.getFile() = getFile() and
+      e.getFile() = this.getFile() and
+      result.getFile() = this.getFile() and
       line = this.getLocation().getStartLine() and
       result.getLocation().getStartLine() < line and
       line < e.getLocation().getEndLine()
@@ -69,7 +69,9 @@ class PreprocessorBranchDirective extends PreprocessorDirective, TPreprocessorBr
    * directives in different translation units, then there can be more than
    * one result.
    */
-  PreprocessorEndif getEndIf() { preprocpair(unresolveElement(getIf()), unresolveElement(result)) }
+  PreprocessorEndif getEndIf() {
+    preprocpair(unresolveElement(this.getIf()), unresolveElement(result))
+  }
 
   /**
    * Gets the next `#elif`, `#else` or `#endif` matching this branching
@@ -137,7 +139,7 @@ class PreprocessorBranch extends PreprocessorBranchDirective, @ppd_branch {
    * which evaluated it, or was not taken by any translation unit which
    * evaluated it.
    */
-  predicate wasPredictable() { not (wasTaken() and wasNotTaken()) }
+  predicate wasPredictable() { not (this.wasTaken() and this.wasNotTaken()) }
 }
 
 /**
@@ -268,7 +270,7 @@ class PreprocessorUndef extends PreprocessorDirective, @ppd_undef {
   /**
    * Gets the name of the macro that is undefined.
    */
-  string getName() { result = getHead() }
+  string getName() { result = this.getHead() }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/Print.qll

@@ -105,8 +105,8 @@ private class DumpType extends Type {
     // for a `SpecifiedType`, insert the qualifiers after
     // `getDeclaratorSuffixBeforeQualifiers()`.
     result =
-      getTypeSpecifier() + getDeclaratorPrefix() + getDeclaratorSuffixBeforeQualifiers() +
-        getDeclaratorSuffix()
+      this.getTypeSpecifier() + this.getDeclaratorPrefix() +
+        this.getDeclaratorSuffixBeforeQualifiers() + this.getDeclaratorSuffix()
   }
 
   /**
@@ -147,29 +147,35 @@ private class DumpType extends Type {
 }
 
 private class BuiltInDumpType extends DumpType, BuiltInType {
-  override string getTypeSpecifier() { result = toString() }
+  override string getTypeSpecifier() { result = this.toString() }
 }
 
 private class IntegralDumpType extends BuiltInDumpType, IntegralType {
-  override string getTypeSpecifier() { result = getCanonicalArithmeticType().toString() }
+  override string getTypeSpecifier() { result = this.getCanonicalArithmeticType().toString() }
 }
 
 private class DerivedDumpType extends DumpType, DerivedType {
-  override string getTypeSpecifier() { result = getBaseType().(DumpType).getTypeSpecifier() }
+  override string getTypeSpecifier() { result = this.getBaseType().(DumpType).getTypeSpecifier() }
 
   override string getDeclaratorSuffixBeforeQualifiers() {
-    result = getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
+    result = this.getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
   }
 
-  override string getDeclaratorSuffix() { result = getBaseType().(DumpType).getDeclaratorSuffix() }
+  override string getDeclaratorSuffix() {
+    result = this.getBaseType().(DumpType).getDeclaratorSuffix()
+  }
 }
 
 private class DecltypeDumpType extends DumpType, Decltype {
-  override string getTypeSpecifier() { result = getBaseType().(DumpType).getTypeSpecifier() }
+  override string getTypeSpecifier() { result = this.getBaseType().(DumpType).getTypeSpecifier() }
 
-  override string getDeclaratorPrefix() { result = getBaseType().(DumpType).getDeclaratorPrefix() }
+  override string getDeclaratorPrefix() {
+    result = this.getBaseType().(DumpType).getDeclaratorPrefix()
+  }
 
-  override string getDeclaratorSuffix() { result = getBaseType().(DumpType).getDeclaratorSuffix() }
+  override string getDeclaratorSuffix() {
+    result = this.getBaseType().(DumpType).getDeclaratorSuffix()
+  }
 }
 
 private class PointerIshDumpType extends DerivedDumpType {
@@ -180,10 +186,10 @@ private class PointerIshDumpType extends DerivedDumpType {
 
   override string getDeclaratorPrefix() {
     exists(string declarator |
-      result = getBaseType().(DumpType).getDeclaratorPrefix() + declarator and
-      if getBaseType().getUnspecifiedType() instanceof ArrayType
-      then declarator = "(" + getDeclaratorToken() + ")"
-      else declarator = getDeclaratorToken()
+      result = this.getBaseType().(DumpType).getDeclaratorPrefix() + declarator and
+      if this.getBaseType().getUnspecifiedType() instanceof ArrayType
+      then declarator = "(" + this.getDeclaratorToken() + ")"
+      else declarator = this.getDeclaratorToken()
     )
   }
 
@@ -206,13 +212,13 @@ private class RValueReferenceDumpType extends PointerIshDumpType, RValueReferenc
 }
 
 private class PointerToMemberDumpType extends DumpType, PointerToMemberType {
-  override string getTypeSpecifier() { result = getBaseType().(DumpType).getTypeSpecifier() }
+  override string getTypeSpecifier() { result = this.getBaseType().(DumpType).getTypeSpecifier() }
 
   override string getDeclaratorPrefix() {
     exists(string declarator, string parenDeclarator, Type baseType |
-      declarator = getClass().(DumpType).getTypeIdentityString() + "::*" and
-      result = getBaseType().(DumpType).getDeclaratorPrefix() + " " + parenDeclarator and
-      baseType = getBaseType().getUnspecifiedType() and
+      declarator = this.getClass().(DumpType).getTypeIdentityString() + "::*" and
+      result = this.getBaseType().(DumpType).getDeclaratorPrefix() + " " + parenDeclarator and
+      baseType = this.getBaseType().getUnspecifiedType() and
       if baseType instanceof ArrayType or baseType instanceof RoutineType
       then parenDeclarator = "(" + declarator
       else parenDeclarator = declarator
@@ -221,38 +227,44 @@ private class PointerToMemberDumpType extends DumpType, PointerToMemberType {
 
   override string getDeclaratorSuffixBeforeQualifiers() {
     exists(Type baseType |
-      baseType = getBaseType().getUnspecifiedType() and
+      baseType = this.getBaseType().getUnspecifiedType() and
       if baseType instanceof ArrayType or baseType instanceof RoutineType
-      then result = ")" + getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
-      else result = getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
+      then result = ")" + this.getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
+      else result = this.getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
     )
   }
 
-  override string getDeclaratorSuffix() { result = getBaseType().(DumpType).getDeclaratorSuffix() }
+  override string getDeclaratorSuffix() {
+    result = this.getBaseType().(DumpType).getDeclaratorSuffix()
+  }
 }
 
 private class ArrayDumpType extends DerivedDumpType, ArrayType {
-  override string getDeclaratorPrefix() { result = getBaseType().(DumpType).getDeclaratorPrefix() }
+  override string getDeclaratorPrefix() {
+    result = this.getBaseType().(DumpType).getDeclaratorPrefix()
+  }
 
   override string getDeclaratorSuffixBeforeQualifiers() {
-    if exists(getArraySize())
+    if exists(this.getArraySize())
     then
       result =
-        "[" + getArraySize().toString() + "]" +
-          getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
-    else result = "[]" + getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
+        "[" + this.getArraySize().toString() + "]" +
+          this.getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
+    else result = "[]" + this.getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
   }
 }
 
 private class FunctionPointerIshDumpType extends DerivedDumpType, FunctionPointerIshType {
   override string getDeclaratorSuffixBeforeQualifiers() {
-    result = ")" + getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
+    result = ")" + this.getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers()
   }
 
-  override string getDeclaratorSuffix() { result = getBaseType().(DumpType).getDeclaratorSuffix() }
+  override string getDeclaratorSuffix() {
+    result = this.getBaseType().(DumpType).getDeclaratorSuffix()
+  }
 
   override string getDeclaratorPrefix() {
-    result = getBaseType().(DumpType).getDeclaratorPrefix() + "(" + getDeclaratorToken()
+    result = this.getBaseType().(DumpType).getDeclaratorPrefix() + "(" + this.getDeclaratorToken()
   }
 
   /**
@@ -274,10 +286,10 @@ private class BlockDumpType extends FunctionPointerIshDumpType, BlockType {
 }
 
 private class RoutineDumpType extends DumpType, RoutineType {
-  override string getTypeSpecifier() { result = getReturnType().(DumpType).getTypeSpecifier() }
+  override string getTypeSpecifier() { result = this.getReturnType().(DumpType).getTypeSpecifier() }
 
   override string getDeclaratorPrefix() {
-    result = getReturnType().(DumpType).getDeclaratorPrefix()
+    result = this.getReturnType().(DumpType).getDeclaratorPrefix()
   }
 
   language[monotonicAggregates]
@@ -285,39 +297,41 @@ private class RoutineDumpType extends DumpType, RoutineType {
     result =
       "(" +
         concat(int i |
-          exists(getParameterType(i))
+          exists(this.getParameterType(i))
         |
-          getParameterTypeString(getParameterType(i)), ", " order by i
+          getParameterTypeString(this.getParameterType(i)), ", " order by i
         ) + ")"
   }
 
   override string getDeclaratorSuffix() {
     result =
-      getReturnType().(DumpType).getDeclaratorSuffixBeforeQualifiers() +
-        getReturnType().(DumpType).getDeclaratorSuffix()
+      this.getReturnType().(DumpType).getDeclaratorSuffixBeforeQualifiers() +
+        this.getReturnType().(DumpType).getDeclaratorSuffix()
   }
 }
 
 private class SpecifiedDumpType extends DerivedDumpType, SpecifiedType {
   override string getDeclaratorPrefix() {
     exists(string basePrefix |
-      basePrefix = getBaseType().(DumpType).getDeclaratorPrefix() and
-      if getBaseType().getUnspecifiedType() instanceof RoutineType
+      basePrefix = this.getBaseType().(DumpType).getDeclaratorPrefix() and
+      if this.getBaseType().getUnspecifiedType() instanceof RoutineType
       then result = basePrefix
-      else result = basePrefix + " " + getSpecifierString()
+      else result = basePrefix + " " + this.getSpecifierString()
     )
   }
 
   override string getDeclaratorSuffixBeforeQualifiers() {
     exists(string baseSuffix |
-      baseSuffix = getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers() and
-      if getBaseType().getUnspecifiedType() instanceof RoutineType
-      then result = baseSuffix + " " + getSpecifierString()
+      baseSuffix = this.getBaseType().(DumpType).getDeclaratorSuffixBeforeQualifiers() and
+      if this.getBaseType().getUnspecifiedType() instanceof RoutineType
+      then result = baseSuffix + " " + this.getSpecifierString()
       else result = baseSuffix
     )
   }
 
-  override string getDeclaratorSuffix() { result = getBaseType().(DumpType).getDeclaratorSuffix() }
+  override string getDeclaratorSuffix() {
+    result = this.getBaseType().(DumpType).getDeclaratorSuffix()
+  }
 }
 
 private class UserDumpType extends DumpType, DumpDeclaration, UserType {
@@ -330,18 +344,18 @@ private class UserDumpType extends DumpType, DumpDeclaration, UserType {
           // "lambda [] type at line 12, col. 40"
           // Use `min(getSimpleName())` to work around an extractor bug where a lambda can have different names
           // from different compilation units.
-          simpleName = "(" + min(getSimpleName()) + ")"
-        else simpleName = getSimpleName()
+          simpleName = "(" + min(this.getSimpleName()) + ")"
+        else simpleName = this.getSimpleName()
       ) and
-      result = getScopePrefix(this) + simpleName + getTemplateArgumentsString()
+      result = getScopePrefix(this) + simpleName + this.getTemplateArgumentsString()
     )
   }
 
-  override string getTypeSpecifier() { result = getIdentityString() }
+  override string getTypeSpecifier() { result = this.getIdentityString() }
 }
 
 private class DumpProxyClass extends UserDumpType, ProxyClass {
-  override string getIdentityString() { result = getName() }
+  override string getIdentityString() { result = this.getName() }
 }
 
 private class DumpVariable extends DumpDeclaration, Variable {
@@ -360,9 +374,9 @@ private class DumpVariable extends DumpDeclaration, Variable {
 private class DumpFunction extends DumpDeclaration, Function {
   override string getIdentityString() {
     result =
-      getType().(DumpType).getTypeSpecifier() + getType().(DumpType).getDeclaratorPrefix() + " " +
-        getScopePrefix(this) + getName() + getTemplateArgumentsString() +
-        getDeclaratorSuffixBeforeQualifiers() + getDeclaratorSuffix()
+      this.getType().(DumpType).getTypeSpecifier() + this.getType().(DumpType).getDeclaratorPrefix()
+        + " " + getScopePrefix(this) + this.getName() + this.getTemplateArgumentsString() +
+        this.getDeclaratorSuffixBeforeQualifiers() + this.getDeclaratorSuffix()
   }
 
   language[monotonicAggregates]
@@ -370,28 +384,29 @@ private class DumpFunction extends DumpDeclaration, Function {
     result =
       "(" +
         concat(int i |
-          exists(getParameter(i).getType())
+          exists(this.getParameter(i).getType())
         |
-          getParameterTypeString(getParameter(i).getType()), ", " order by i
-        ) + ")" + getQualifierString()
+          getParameterTypeString(this.getParameter(i).getType()), ", " order by i
+        ) + ")" + this.getQualifierString()
   }
 
   private string getQualifierString() {
-    if exists(getACVQualifier())
+    if exists(this.getACVQualifier())
     then
-      result = " " + strictconcat(string qualifier | qualifier = getACVQualifier() | qualifier, " ")
+      result =
+        " " + strictconcat(string qualifier | qualifier = this.getACVQualifier() | qualifier, " ")
     else result = ""
   }
 
   private string getACVQualifier() {
-    result = getASpecifier().getName() and
+    result = this.getASpecifier().getName() and
     result = ["const", "volatile"]
   }
 
   private string getDeclaratorSuffix() {
     result =
-      getType().(DumpType).getDeclaratorSuffixBeforeQualifiers() +
-        getType().(DumpType).getDeclaratorSuffix()
+      this.getType().(DumpType).getDeclaratorSuffixBeforeQualifiers() +
+        this.getType().(DumpType).getDeclaratorSuffix()
   }
 }
 

cpp/ql/lib/semmle/code/cpp/Specifier.qll

@@ -31,11 +31,7 @@ class Specifier extends Element, @specifier {
  * A C/C++ function specifier: `inline`, `virtual`, or `explicit`.
  */
 class FunctionSpecifier extends Specifier {
-  FunctionSpecifier() {
-    this.hasName("inline") or
-    this.hasName("virtual") or
-    this.hasName("explicit")
-  }
+  FunctionSpecifier() { this.hasName(["inline", "virtual", "explicit"]) }
 
   override string getAPrimaryQlClass() { result = "FunctionSpecifier" }
 }
@@ -45,13 +41,7 @@ class FunctionSpecifier extends Specifier {
  * or `mutable".
  */
 class StorageClassSpecifier extends Specifier {
-  StorageClassSpecifier() {
-    this.hasName("auto") or
-    this.hasName("register") or
-    this.hasName("static") or
-    this.hasName("extern") or
-    this.hasName("mutable")
-  }
+  StorageClassSpecifier() { this.hasName(["auto", "register", "static", "extern", "mutable"]) }
 
   override string getAPrimaryQlClass() { result = "StorageClassSpecifier" }
 }
@@ -60,11 +50,7 @@ class StorageClassSpecifier extends Specifier {
  * A C++ access specifier: `public`, `protected`, or `private`.
  */
 class AccessSpecifier extends Specifier {
-  AccessSpecifier() {
-    this.hasName("public") or
-    this.hasName("protected") or
-    this.hasName("private")
-  }
+  AccessSpecifier() { this.hasName(["public", "protected", "private"]) }
 
   /**
    * Gets the visibility of a field with access specifier `this` if it is
@@ -140,7 +126,7 @@ class Attribute extends Element, @attribute {
   AttributeArgument getArgument(int i) { result.getAttribute() = this and result.getIndex() = i }
 
   /** Gets an argument of the attribute. */
-  AttributeArgument getAnArgument() { result = getArgument(_) }
+  AttributeArgument getAnArgument() { result = this.getArgument(_) }
 }
 
 /**
@@ -166,7 +152,7 @@ class StdAttribute extends Attribute, @stdattribute {
    * Holds if this attribute has the given namespace and name.
    */
   predicate hasQualifiedName(string namespace, string name) {
-    namespace = getNamespace() and hasName(name)
+    namespace = this.getNamespace() and this.hasName(name)
   }
 }
 
@@ -184,7 +170,7 @@ class Declspec extends Attribute, @declspec { }
  */
 class MicrosoftAttribute extends Attribute, @msattribute {
   AttributeArgument getNamedArgument(string name) {
-    result = getAnArgument() and result.getName() = name
+    result = this.getAnArgument() and result.getName() = name
   }
 }
 
@@ -212,13 +198,13 @@ class AlignAs extends Attribute, @alignas {
  * ```
  */
 class FormatAttribute extends GnuAttribute {
-  FormatAttribute() { getName() = "format" }
+  FormatAttribute() { this.getName() = "format" }
 
   /**
    * Gets the archetype of this format attribute, for example
    * `"printf"`.
    */
-  string getArchetype() { result = getArgument(0).getValueText() }
+  string getArchetype() { result = this.getArgument(0).getValueText() }
 
   /**
    * Gets the index in (1-based) format attribute notation associated
@@ -236,7 +222,7 @@ class FormatAttribute extends GnuAttribute {
    * Gets the (0-based) index of the format string,
    * according to this attribute.
    */
-  int getFormatIndex() { result = getArgument(1).getValueInt() - firstArgumentNumber() }
+  int getFormatIndex() { result = this.getArgument(1).getValueInt() - this.firstArgumentNumber() }
 
   /**
    * Gets the (0-based) index of the first format argument (if any),
@@ -244,8 +230,8 @@ class FormatAttribute extends GnuAttribute {
    */
   int getFirstFormatArgIndex() {
     exists(int val |
-      val = getArgument(2).getValueInt() and
-      result = val - firstArgumentNumber() and
+      val = this.getArgument(2).getValueInt() and
+      result = val - this.firstArgumentNumber() and
       not val = 0 // indicates a `vprintf` style format function with arguments not directly available.
     )
   }
@@ -277,7 +263,7 @@ class AttributeArgument extends Element, @attribute_arg {
   /**
    * Gets the value of this argument, if its value is integral.
    */
-  int getValueInt() { result = getValueText().toInt() }
+  int getValueInt() { result = this.getValueText().toInt() }
 
   /**
    * Gets the value of this argument, if its value is a type.
@@ -304,11 +290,11 @@ class AttributeArgument extends Element, @attribute_arg {
     then result = "empty argument"
     else
       exists(string prefix, string tail |
-        (if exists(getName()) then prefix = getName() + "=" else prefix = "") and
+        (if exists(this.getName()) then prefix = this.getName() + "=" else prefix = "") and
         (
           if exists(@attribute_arg_type self | self = underlyingElement(this))
-          then tail = getValueType().getName()
-          else tail = getValueText()
+          then tail = this.getValueType().getName()
+          else tail = this.getValueText()
         ) and
         result = prefix + tail
       )

cpp/ql/lib/semmle/code/cpp/Struct.qll

@@ -41,7 +41,7 @@ class Struct extends Class {
  * ```
  */
 class LocalStruct extends Struct {
-  LocalStruct() { isLocal() }
+  LocalStruct() { this.isLocal() }
 
   override string getAPrimaryQlClass() { not this instanceof LocalUnion and result = "LocalStruct" }
 }

cpp/ql/lib/semmle/code/cpp/TestFile.qll

@@ -10,8 +10,8 @@ import semmle.code.cpp.File
  */
 private class GoogleTestHeader extends File {
   GoogleTestHeader() {
-    getBaseName() = "gtest.h" and
-    getParentContainer().getBaseName() = "gtest"
+    this.getBaseName() = "gtest.h" and
+    this.getParentContainer().getBaseName() = "gtest"
   }
 }
 
@@ -30,8 +30,8 @@ private class GoogleTest extends MacroInvocation {
  */
 private class BoostTestFolder extends Folder {
   BoostTestFolder() {
-    getBaseName() = "test" and
-    getParentContainer().getBaseName() = "boost"
+    this.getBaseName() = "test" and
+    this.getParentContainer().getBaseName() = "boost"
   }
 }
 
@@ -49,7 +49,7 @@ private class BoostTest extends MacroInvocation {
  * The `cppunit` directory.
  */
 private class CppUnitFolder extends Folder {
-  CppUnitFolder() { getBaseName() = "cppunit" }
+  CppUnitFolder() { this.getBaseName() = "cppunit" }
 }
 
 /**
@@ -57,8 +57,8 @@ private class CppUnitFolder extends Folder {
  */
 private class CppUnitClass extends Class {
   CppUnitClass() {
-    getFile().getParentContainer+() instanceof CppUnitFolder and
-    getNamespace().getParentNamespace*().getName() = "CppUnit"
+    this.getFile().getParentContainer+() instanceof CppUnitFolder and
+    this.getNamespace().getParentNamespace*().getName() = "CppUnit"
   }
 }
 

cpp/ql/lib/semmle/code/cpp/Type.qll

@@ -81,7 +81,7 @@ class Type extends Locatable, @type {
    * Holds if this type refers to type `t` (by default,
    * a type always refers to itself).
    */
-  predicate refersTo(Type t) { refersToDirectly*(t) }
+  predicate refersTo(Type t) { this.refersToDirectly*(t) }
 
   /**
    * Holds if this type refers to type `t` directly.
@@ -1080,11 +1080,11 @@ class DerivedType extends Type, @derivedtype {
 
   override predicate refersToDirectly(Type t) { t = this.getBaseType() }
 
-  override predicate involvesReference() { getBaseType().involvesReference() }
+  override predicate involvesReference() { this.getBaseType().involvesReference() }
 
-  override predicate involvesTemplateParameter() { getBaseType().involvesTemplateParameter() }
+  override predicate involvesTemplateParameter() { this.getBaseType().involvesTemplateParameter() }
 
-  override Type stripType() { result = getBaseType().stripType() }
+  override Type stripType() { result = this.getBaseType().stripType() }
 
   /**
    * Holds if this type has the `__autoreleasing` specifier or if it points to
@@ -1165,33 +1165,35 @@ class Decltype extends Type, @decltype {
    */
   predicate parenthesesWouldChangeMeaning() { decltypes(underlyingElement(this), _, _, true) }
 
-  override Type getUnderlyingType() { result = getBaseType().getUnderlyingType() }
+  override Type getUnderlyingType() { result = this.getBaseType().getUnderlyingType() }
 
-  override Type stripTopLevelSpecifiers() { result = getBaseType().stripTopLevelSpecifiers() }
+  override Type stripTopLevelSpecifiers() { result = this.getBaseType().stripTopLevelSpecifiers() }
 
-  override Type stripType() { result = getBaseType().stripType() }
+  override Type stripType() { result = this.getBaseType().stripType() }
 
-  override Type resolveTypedefs() { result = getBaseType().resolveTypedefs() }
+  override Type resolveTypedefs() { result = this.getBaseType().resolveTypedefs() }
 
-  override Location getLocation() { result = getExpr().getLocation() }
+  override Location getLocation() { result = this.getExpr().getLocation() }
 
   override string toString() { result = "decltype(...)" }
 
   override string getName() { none() }
 
-  override int getSize() { result = getBaseType().getSize() }
+  override int getSize() { result = this.getBaseType().getSize() }
 
-  override int getAlignment() { result = getBaseType().getAlignment() }
+  override int getAlignment() { result = this.getBaseType().getAlignment() }
 
-  override int getPointerIndirectionLevel() { result = getBaseType().getPointerIndirectionLevel() }
+  override int getPointerIndirectionLevel() {
+    result = this.getBaseType().getPointerIndirectionLevel()
+  }
 
   override string explain() {
     result = "decltype resulting in {" + this.getBaseType().explain() + "}"
   }
 
-  override predicate involvesReference() { getBaseType().involvesReference() }
+  override predicate involvesReference() { this.getBaseType().involvesReference() }
 
-  override predicate involvesTemplateParameter() { getBaseType().involvesTemplateParameter() }
+  override predicate involvesTemplateParameter() { this.getBaseType().involvesTemplateParameter() }
 
   override predicate isDeeplyConst() { this.getBaseType().isDeeplyConst() }
 
@@ -1223,7 +1225,7 @@ class PointerType extends DerivedType {
   override predicate isDeeplyConstBelow() { this.getBaseType().isDeeplyConst() }
 
   override Type resolveTypedefs() {
-    result.(PointerType).getBaseType() = getBaseType().resolveTypedefs()
+    result.(PointerType).getBaseType() = this.getBaseType().resolveTypedefs()
   }
 }
 
@@ -1240,7 +1242,9 @@ class ReferenceType extends DerivedType {
 
   override string getAPrimaryQlClass() { result = "ReferenceType" }
 
-  override int getPointerIndirectionLevel() { result = getBaseType().getPointerIndirectionLevel() }
+  override int getPointerIndirectionLevel() {
+    result = this.getBaseType().getPointerIndirectionLevel()
+  }
 
   override string explain() { result = "reference to {" + this.getBaseType().explain() + "}" }
 
@@ -1251,7 +1255,7 @@ class ReferenceType extends DerivedType {
   override predicate involvesReference() { any() }
 
   override Type resolveTypedefs() {
-    result.(ReferenceType).getBaseType() = getBaseType().resolveTypedefs()
+    result.(ReferenceType).getBaseType() = this.getBaseType().resolveTypedefs()
   }
 }
 
@@ -1330,11 +1334,11 @@ class SpecifiedType extends DerivedType {
   }
 
   override Type resolveTypedefs() {
-    result.(SpecifiedType).getBaseType() = getBaseType().resolveTypedefs() and
-    result.getASpecifier() = getASpecifier()
+    result.(SpecifiedType).getBaseType() = this.getBaseType().resolveTypedefs() and
+    result.getASpecifier() = this.getASpecifier()
   }
 
-  override Type stripTopLevelSpecifiers() { result = getBaseType().stripTopLevelSpecifiers() }
+  override Type stripTopLevelSpecifiers() { result = this.getBaseType().stripTopLevelSpecifiers() }
 }
 
 /**
@@ -1433,7 +1437,8 @@ class GNUVectorType extends DerivedType {
   override int getAlignment() { arraysizes(underlyingElement(this), _, _, result) }
 
   override string explain() {
-    result = "GNU " + getNumElements() + " element vector of {" + this.getBaseType().explain() + "}"
+    result =
+      "GNU " + this.getNumElements() + " element vector of {" + this.getBaseType().explain() + "}"
   }
 
   override predicate isDeeplyConstBelow() { this.getBaseType().isDeeplyConst() }
@@ -1468,7 +1473,9 @@ class FunctionReferenceType extends FunctionPointerIshType {
 
   override string getAPrimaryQlClass() { result = "FunctionReferenceType" }
 
-  override int getPointerIndirectionLevel() { result = getBaseType().getPointerIndirectionLevel() }
+  override int getPointerIndirectionLevel() {
+    result = this.getBaseType().getPointerIndirectionLevel()
+  }
 
   override string explain() {
     result = "reference to {" + this.getBaseType().(RoutineType).explain() + "}"
@@ -1535,8 +1542,8 @@ class FunctionPointerIshType extends DerivedType {
   int getNumberOfParameters() { result = count(int i | exists(this.getParameterType(i))) }
 
   override predicate involvesTemplateParameter() {
-    getReturnType().involvesTemplateParameter() or
-    getAParameterType().involvesTemplateParameter()
+    this.getReturnType().involvesTemplateParameter() or
+    this.getAParameterType().involvesTemplateParameter()
   }
 
   override predicate isDeeplyConstBelow() { this.getBaseType().isDeeplyConst() }
@@ -1581,7 +1588,7 @@ class PointerToMemberType extends Type, @ptrtomember {
         this.getBaseType().explain() + "}"
   }
 
-  override predicate involvesTemplateParameter() { getBaseType().involvesTemplateParameter() }
+  override predicate involvesTemplateParameter() { this.getBaseType().involvesTemplateParameter() }
 
   override predicate isDeeplyConstBelow() { this.getBaseType().isDeeplyConst() }
 }
@@ -1650,7 +1657,6 @@ class RoutineType extends Type, @routinetype {
     i = 0 and result = "" and not exists(this.getAParameterType())
     or
     (
-      exists(this.getParameterType(i)) and
       if i < max(int j | exists(this.getParameterType(j)))
       then
         // Not the last one
@@ -1671,8 +1677,8 @@ class RoutineType extends Type, @routinetype {
   override predicate isDeeplyConstBelow() { none() } // Current limitation: no such thing as a const routine type
 
   override predicate involvesTemplateParameter() {
-    getReturnType().involvesTemplateParameter() or
-    getAParameterType().involvesTemplateParameter()
+    this.getReturnType().involvesTemplateParameter() or
+    this.getAParameterType().involvesTemplateParameter()
   }
 }
 

cpp/ql/lib/semmle/code/cpp/TypedefType.qll

@@ -25,7 +25,7 @@ class TypedefType extends UserType {
 
   override Type getUnderlyingType() { result = this.getBaseType().getUnderlyingType() }
 
-  override Type stripTopLevelSpecifiers() { result = getBaseType().stripTopLevelSpecifiers() }
+  override Type stripTopLevelSpecifiers() { result = this.getBaseType().stripTopLevelSpecifiers() }
 
   override int getSize() { result = this.getBaseType().getSize() }
 
@@ -43,11 +43,11 @@ class TypedefType extends UserType {
     result = this.getBaseType().getASpecifier()
   }
 
-  override predicate involvesReference() { getBaseType().involvesReference() }
+  override predicate involvesReference() { this.getBaseType().involvesReference() }
 
-  override Type resolveTypedefs() { result = getBaseType().resolveTypedefs() }
+  override Type resolveTypedefs() { result = this.getBaseType().resolveTypedefs() }
 
-  override Type stripType() { result = getBaseType().stripType() }
+  override Type stripType() { result = this.getBaseType().stripType() }
 }
 
 /**
@@ -90,7 +90,7 @@ class UsingAliasTypedefType extends TypedefType {
  * ```
  */
 class LocalTypedefType extends TypedefType {
-  LocalTypedefType() { isLocal() }
+  LocalTypedefType() { this.isLocal() }
 
   override string getAPrimaryQlClass() { result = "LocalTypedefType" }
 }

cpp/ql/lib/semmle/code/cpp/Union.qll

@@ -37,7 +37,7 @@ class Union extends Struct {
  * ```
  */
 class LocalUnion extends Union {
-  LocalUnion() { isLocal() }
+  LocalUnion() { this.isLocal() }
 
   override string getAPrimaryQlClass() { result = "LocalUnion" }
 }

cpp/ql/lib/semmle/code/cpp/UserType.qll

@@ -30,19 +30,19 @@ class UserType extends Type, Declaration, NameQualifyingElement, AccessHolder, @
    * Gets the simple name of this type, without any template parameters.  For example
    * if the name of the type is `"myType<int>"`, the simple name is just `"myType"`.
    */
-  string getSimpleName() { result = getName().regexpReplaceAll("<.*", "") }
+  string getSimpleName() { result = this.getName().regexpReplaceAll("<.*", "") }
 
   override predicate hasName(string name) { usertypes(underlyingElement(this), name, _) }
 
   /** Holds if this type is anonymous. */
-  predicate isAnonymous() { getName().matches("(unnamed%") }
+  predicate isAnonymous() { this.getName().matches("(unnamed%") }
 
   override predicate hasSpecifier(string s) { Type.super.hasSpecifier(s) }
 
   override Specifier getASpecifier() { result = Type.super.getASpecifier() }
 
   override Location getLocation() {
-    if hasDefinition()
+    if this.hasDefinition()
     then result = this.getDefinitionLocation()
     else result = this.getADeclarationLocation()
   }
@@ -53,16 +53,16 @@ class UserType extends Type, Declaration, NameQualifyingElement, AccessHolder, @
     else exists(Class t | this.(Class).isConstructedFrom(t) and result = t.getADeclarationEntry())
   }
 
-  override Location getADeclarationLocation() { result = getADeclarationEntry().getLocation() }
+  override Location getADeclarationLocation() { result = this.getADeclarationEntry().getLocation() }
 
   override TypeDeclarationEntry getDefinition() {
-    result = getADeclarationEntry() and
+    result = this.getADeclarationEntry() and
     result.isDefinition()
   }
 
   override Location getDefinitionLocation() {
-    if exists(getDefinition())
-    then result = getDefinition().getLocation()
+    if exists(this.getDefinition())
+    then result = this.getDefinition().getLocation()
     else
       exists(Class t |
         this.(Class).isConstructedFrom(t) and result = t.getDefinition().getLocation()
@@ -80,7 +80,7 @@ class UserType extends Type, Declaration, NameQualifyingElement, AccessHolder, @
    * Holds if this is a local type (that is, a type that has a directly-enclosing
    * function).
    */
-  predicate isLocal() { exists(getEnclosingFunction()) }
+  predicate isLocal() { exists(this.getEnclosingFunction()) }
 
   /*
    * Dummy implementations of inherited methods. This class must not be
@@ -107,9 +107,9 @@ class UserType extends Type, Declaration, NameQualifyingElement, AccessHolder, @
  * ```
  */
 class TypeDeclarationEntry extends DeclarationEntry, @type_decl {
-  override UserType getDeclaration() { result = getType() }
+  override UserType getDeclaration() { result = this.getType() }
 
-  override string getName() { result = getType().getName() }
+  override string getName() { result = this.getType().getName() }
 
   override string getAPrimaryQlClass() { result = "TypeDeclarationEntry" }
 

cpp/ql/lib/semmle/code/cpp/Variable.qll

@@ -104,17 +104,17 @@ class Variable extends Declaration, @variable {
 
   override VariableDeclarationEntry getADeclarationEntry() { result.getDeclaration() = this }
 
-  override Location getADeclarationLocation() { result = getADeclarationEntry().getLocation() }
+  override Location getADeclarationLocation() { result = this.getADeclarationEntry().getLocation() }
 
   override VariableDeclarationEntry getDefinition() {
-    result = getADeclarationEntry() and
+    result = this.getADeclarationEntry() and
     result.isDefinition()
   }
 
-  override Location getDefinitionLocation() { result = getDefinition().getLocation() }
+  override Location getDefinitionLocation() { result = this.getDefinition().getLocation() }
 
   override Location getLocation() {
-    if exists(getDefinition())
+    if exists(this.getDefinition())
     then result = this.getDefinitionLocation()
     else result = this.getADeclarationLocation()
   }
@@ -199,7 +199,7 @@ class Variable extends Declaration, @variable {
  * ```
  */
 class VariableDeclarationEntry extends DeclarationEntry, @var_decl {
-  override Variable getDeclaration() { result = getVariable() }
+  override Variable getDeclaration() { result = this.getVariable() }
 
   override string getAPrimaryQlClass() { result = "VariableDeclarationEntry" }
 
@@ -276,32 +276,33 @@ class ParameterDeclarationEntry extends VariableDeclarationEntry {
   int getIndex() { param_decl_bind(underlyingElement(this), result, _) }
 
   private string getAnonymousParameterDescription() {
-    not exists(getName()) and
+    not exists(this.getName()) and
     exists(string idx |
       idx =
-        ((getIndex() + 1).toString() + "th")
+        ((this.getIndex() + 1).toString() + "th")
             .replaceAll("1th", "1st")
             .replaceAll("2th", "2nd")
             .replaceAll("3th", "3rd")
             .replaceAll("11st", "11th")
             .replaceAll("12nd", "12th")
             .replaceAll("13rd", "13th") and
-      if exists(getCanonicalName())
-      then result = "declaration of " + getCanonicalName() + " as anonymous " + idx + " parameter"
+      if exists(this.getCanonicalName())
+      then
+        result = "declaration of " + this.getCanonicalName() + " as anonymous " + idx + " parameter"
       else result = "declaration of " + idx + " parameter"
     )
   }
 
   override string toString() {
-    isDefinition() and
-    result = "definition of " + getName()
+    this.isDefinition() and
+    result = "definition of " + this.getName()
     or
-    not isDefinition() and
-    if getName() = getCanonicalName()
-    then result = "declaration of " + getName()
-    else result = "declaration of " + getCanonicalName() + " as " + getName()
+    not this.isDefinition() and
+    if this.getName() = this.getCanonicalName()
+    then result = "declaration of " + this.getName()
+    else result = "declaration of " + this.getCanonicalName() + " as " + this.getName()
     or
-    result = getAnonymousParameterDescription()
+    result = this.getAnonymousParameterDescription()
   }
 
   /**
@@ -311,8 +312,12 @@ class ParameterDeclarationEntry extends VariableDeclarationEntry {
    */
   string getTypedName() {
     exists(string typeString, string nameString |
-      (if exists(getType().getName()) then typeString = getType().getName() else typeString = "") and
-      (if exists(getName()) then nameString = getName() else nameString = "") and
+      (
+        if exists(this.getType().getName())
+        then typeString = this.getType().getName()
+        else typeString = ""
+      ) and
+      (if exists(this.getName()) then nameString = this.getName() else nameString = "") and
       if typeString != "" and nameString != ""
       then result = typeString + " " + nameString
       else result = typeString + nameString
@@ -540,7 +545,7 @@ class MemberVariable extends Variable, @membervariable {
   }
 
   /** Holds if this member is mutable. */
-  predicate isMutable() { getADeclarationEntry().hasSpecifier("mutable") }
+  predicate isMutable() { this.getADeclarationEntry().hasSpecifier("mutable") }
 
   private Type getAType() { membervariables(underlyingElement(this), unresolveElement(result), _) }
 }

cpp/ql/lib/semmle/code/cpp/XML.qll

@@ -24,7 +24,7 @@ class XMLLocatable extends @xmllocatable, TXMLLocatable {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -108,7 +108,7 @@ class XMLParent extends @xmlparent {
   }
 
   /** Gets the text value contained in this XML parent. */
-  string getTextValue() { result = allCharactersString() }
+  string getTextValue() { result = this.allCharactersString() }
 
   /** Gets a printable representation of this XML parent. */
   string toString() { result = this.getName() }
@@ -119,7 +119,7 @@ class XMLFile extends XMLParent, File {
   XMLFile() { xmlEncoding(this, _) }
 
   /** Gets a printable representation of this XML file. */
-  override string toString() { result = getName() }
+  override string toString() { result = this.getName() }
 
   /** Gets the name of this XML file. */
   override string getName() { result = File.super.getAbsolutePath() }
@@ -129,14 +129,14 @@ class XMLFile extends XMLParent, File {
    *
    * Gets the path of this XML file.
    */
-  deprecated string getPath() { result = getAbsolutePath() }
+  deprecated string getPath() { result = this.getAbsolutePath() }
 
   /**
    * DEPRECATED: Use `getParentContainer().getAbsolutePath()` instead.
    *
    * Gets the path of the folder that contains this XML file.
    */
-  deprecated string getFolder() { result = getParentContainer().getAbsolutePath() }
+  deprecated string getFolder() { result = this.getParentContainer().getAbsolutePath() }
 
   /** Gets the encoding of this XML file. */
   string getEncoding() { xmlEncoding(this, result) }
@@ -200,7 +200,7 @@ class XMLDTD extends XMLLocatable, @xmldtd {
  */
 class XMLElement extends @xmlelement, XMLParent, XMLLocatable {
   /** Holds if this XML element has the given `name`. */
-  predicate hasName(string name) { name = getName() }
+  predicate hasName(string name) { name = this.getName() }
 
   /** Gets the name of this XML element. */
   override string getName() { xmlElements(this, result, _, _, _) }
@@ -239,7 +239,7 @@ class XMLElement extends @xmlelement, XMLParent, XMLLocatable {
   string getAttributeValue(string name) { result = this.getAttribute(name).getValue() }
 
   /** Gets a printable representation of this XML element. */
-  override string toString() { result = getName() }
+  override string toString() { result = this.getName() }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/commons/Buffer.qll

@@ -2,53 +2,19 @@ import cpp
 import semmle.code.cpp.dataflow.DataFlow
 
 /**
- * Holds if `v` is a member variable of `c` that looks like it might be variable sized in practice.  For
- * example:
+ * Holds if `v` is a member variable of `c` that looks like it might be variable sized
+ * in practice. For example:
  * ```
  * struct myStruct { // c
  *   int amount;
  *   char data[1]; // v
  * };
  * ```
- * This requires that `v` is an array of size 0 or 1, and `v` is the last member of `c`.  In addition,
- * there must be at least one instance where a `c` pointer is allocated with additional space.  For
- * example, holds for `c` if it occurs as
- * ```
- * malloc(sizeof(c) + 100 * sizeof(char))
- * ```
- * but not if it only ever occurs as
- * ```
- * malloc(sizeof(c))
- * ```
+ * This requires that `v` is an array of size 0 or 1.
  */
 predicate memberMayBeVarSize(Class c, MemberVariable v) {
-  exists(int i |
-    // `v` is the last field in `c`
-    i = max(int j | c.getCanonicalMember(j) instanceof Field | j) and
-    v = c.getCanonicalMember(i) and
-    // v is an array of size at most 1
-    v.getUnspecifiedType().(ArrayType).getArraySize() <= 1
-  ) and
-  (
-    exists(SizeofOperator so |
-      // `sizeof(c)` is taken
-      so.(SizeofTypeOperator).getTypeOperand().getUnspecifiedType() = c or
-      so.(SizeofExprOperator).getExprOperand().getUnspecifiedType() = c
-    |
-      // arithmetic is performed on the result
-      so.getParent*() instanceof AddExpr
-    )
-    or
-    exists(AddressOfExpr aoe |
-      // `&(c.v)` is taken
-      aoe.getAddressable() = v
-    )
-    or
-    exists(BuiltInOperationBuiltInOffsetOf oo |
-      // `offsetof(c, v)` using a builtin
-      oo.getAChild().(VariableAccess).getTarget() = v
-    )
-  )
+  c = v.getDeclaringType() and
+  v.getUnspecifiedType().(ArrayType).getArraySize() <= 1
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/commons/CommonType.qll

@@ -375,8 +375,8 @@ class Wchar_t extends Type {
 class MicrosoftInt8Type extends IntegralType {
   MicrosoftInt8Type() {
     this instanceof CharType and
-    not isExplicitlyUnsigned() and
-    not isExplicitlySigned()
+    not this.isExplicitlyUnsigned() and
+    not this.isExplicitlySigned()
   }
 }
 
@@ -391,8 +391,8 @@ class MicrosoftInt8Type extends IntegralType {
 class MicrosoftInt16Type extends IntegralType {
   MicrosoftInt16Type() {
     this instanceof ShortType and
-    not isExplicitlyUnsigned() and
-    not isExplicitlySigned()
+    not this.isExplicitlyUnsigned() and
+    not this.isExplicitlySigned()
   }
 }
 
@@ -407,8 +407,8 @@ class MicrosoftInt16Type extends IntegralType {
 class MicrosoftInt32Type extends IntegralType {
   MicrosoftInt32Type() {
     this instanceof IntType and
-    not isExplicitlyUnsigned() and
-    not isExplicitlySigned()
+    not this.isExplicitlyUnsigned() and
+    not this.isExplicitlySigned()
   }
 }
 
@@ -423,8 +423,8 @@ class MicrosoftInt32Type extends IntegralType {
 class MicrosoftInt64Type extends IntegralType {
   MicrosoftInt64Type() {
     this instanceof LongLongType and
-    not isExplicitlyUnsigned() and
-    not isExplicitlySigned()
+    not this.isExplicitlyUnsigned() and
+    not this.isExplicitlySigned()
   }
 }
 

cpp/ql/lib/semmle/code/cpp/commons/Dependency.qll

@@ -33,7 +33,7 @@ DependencyOptions getDependencyOptions() { any() }
 class DependsSource extends Element {
   DependsSource() {
     // not inside a template instantiation
-    not exists(Element other | isFromTemplateInstantiation(other)) or
+    not exists(Element other | this.isFromTemplateInstantiation(other)) or
     // allow DeclarationEntrys of template specializations
     this.(DeclarationEntry).getDeclaration().(Function).isConstructedFrom(_) or
     this.(DeclarationEntry).getDeclaration().(Class).isConstructedFrom(_)

cpp/ql/lib/semmle/code/cpp/commons/NullTermination.qll

@@ -1,6 +1,7 @@
 import cpp
 private import semmle.code.cpp.models.interfaces.ArrayFunction
 private import semmle.code.cpp.models.implementations.Strcat
+import semmle.code.cpp.dataflow.DataFlow
 
 private predicate mayAddNullTerminatorHelper(Expr e, VariableAccess va, Expr e0) {
   exists(StackVariable v0, Expr val |
@@ -45,22 +46,28 @@ predicate mayAddNullTerminator(Expr e, VariableAccess va) {
     ae.getRValue().getAChild*() = va
   )
   or
-  // Function call: library function, varargs function, function
-  // containing assembler code, or function where the relevant
-  // parameter is potentially added a null terminator.
+  // Function calls...
   exists(Call c, Function f, int i |
     e = c and
     f = c.getTarget() and
     not functionArgumentMustBeNullTerminated(f, i) and
     c.getAnArgumentSubExpr(i) = va
   |
-    not f.hasEntryPoint() and not functionArgumentMustBeNullTerminated(f, i)
+    // library function
+    not f.hasEntryPoint()
     or
+    // function where the relevant parameter is potentially added a null terminator
     mayAddNullTerminator(_, f.getParameter(i).getAnAccess())
     or
+    // varargs function
     f.isVarargs() and i >= f.getNumberOfParameters()
     or
+    // function containing assembler code
     exists(AsmStmt s | s.getEnclosingFunction() = f)
+    or
+    // function where the relevant parameter is returned (leaking it to be potentially null terminated elsewhere)
+    DataFlow::localFlow(DataFlow::parameterNode(f.getParameter(i)),
+      DataFlow::exprNode(any(ReturnStmt rs).getExpr()))
   )
   or
   // Call without target (e.g., function pointer call)
@@ -93,6 +100,15 @@ predicate variableMustBeNullTerminated(VariableAccess va) {
       fc.getArgument(i) = va
     )
     or
+    // String argument to a formatting function (such as `printf`)
+    exists(int n, FormatLiteral fl |
+      fc.(FormattingFunctionCall).getConversionArgument(n) = va and
+      fl = fc.(FormattingFunctionCall).getFormat() and
+      fl.getConversionType(n) instanceof PointerType and // `%s`, `%ws` etc
+      not fl.getConversionType(n) instanceof VoidPointerType and // exclude: `%p`
+      not fl.hasPrecision(n) // exclude: `%.*s`
+    )
+    or
     // Call to a wrapper function that requires null termination
     // (not itself adding a null terminator)
     exists(Function wrapper, int i, Parameter p, VariableAccess use |

cpp/ql/lib/semmle/code/cpp/commons/Printf.qll

@@ -8,7 +8,7 @@ import semmle.code.cpp.commons.StringAnalysis
 import semmle.code.cpp.models.interfaces.FormattingFunction
 
 class PrintfFormatAttribute extends FormatAttribute {
-  PrintfFormatAttribute() { getArchetype() = ["printf", "__printf__"] }
+  PrintfFormatAttribute() { this.getArchetype() = ["printf", "__printf__"] }
 }
 
 /**
@@ -20,13 +20,13 @@ class AttributeFormattingFunction extends FormattingFunction {
 
   AttributeFormattingFunction() {
     exists(PrintfFormatAttribute printf_attrib |
-      printf_attrib = getAnAttribute() and
+      printf_attrib = this.getAnAttribute() and
       exists(printf_attrib.getFirstFormatArgIndex()) // exclude `vprintf` style format functions
     )
   }
 
   override int getFormatParameterIndex() {
-    forex(PrintfFormatAttribute printf_attrib | printf_attrib = getAnAttribute() |
+    forex(PrintfFormatAttribute printf_attrib | printf_attrib = this.getAnAttribute() |
       result = printf_attrib.getFormatIndex()
     )
   }
@@ -132,7 +132,7 @@ deprecated predicate variadicFormatter(Function f, int formatParamIndex) {
 class UserDefinedFormattingFunction extends FormattingFunction {
   override string getAPrimaryQlClass() { result = "UserDefinedFormattingFunction" }
 
-  UserDefinedFormattingFunction() { isVarargs() and callsVariadicFormatter(this, _, _, _) }
+  UserDefinedFormattingFunction() { this.isVarargs() and callsVariadicFormatter(this, _, _, _) }
 
   override int getFormatParameterIndex() { callsVariadicFormatter(this, _, result, _) }
 
@@ -191,7 +191,7 @@ class FormattingFunctionCall extends Expr {
     exists(int i |
       result = this.getArgument(i) and
       n >= 0 and
-      n = i - getTarget().(FormattingFunction).getFirstFormatArgumentIndex()
+      n = i - this.getTarget().(FormattingFunction).getFirstFormatArgumentIndex()
     )
   }
 
@@ -251,7 +251,22 @@ class FormattingFunctionCall extends Expr {
   int getNumFormatArgument() {
     result = count(this.getFormatArgument(_)) and
     // format arguments must be known
-    exists(getTarget().(FormattingFunction).getFirstFormatArgumentIndex())
+    exists(this.getTarget().(FormattingFunction).getFirstFormatArgumentIndex())
+  }
+
+  /**
+   * Gets the argument, if any, to which the output is written. If `isStream` is
+   * `true`, the output argument is a stream (that is, this call behaves like
+   * `fprintf`). If `isStream` is `false`, the output argument is a buffer (that
+   * is, this call behaves like `sprintf`)
+   */
+  Expr getOutputArgument(boolean isStream) {
+    result =
+      this.(Call)
+          .getArgument(this.(Call)
+                .getTarget()
+                .(FormattingFunction)
+                .getOutputParameterIndex(isStream))
   }
 }
 
@@ -275,7 +290,7 @@ class FormatLiteral extends Literal {
    * DEPRECATED: Use getDefaultCharType() instead.
    */
   deprecated predicate isWideCharDefault() {
-    getUse().getTarget().(FormattingFunction).isWideCharDefault()
+    this.getUse().getTarget().(FormattingFunction).isWideCharDefault()
   }
 
   /**
@@ -283,7 +298,7 @@ class FormatLiteral extends Literal {
    * `char` or `wchar_t`.
    */
   Type getDefaultCharType() {
-    result = getUse().getTarget().(FormattingFunction).getDefaultCharType()
+    result = this.getUse().getTarget().(FormattingFunction).getDefaultCharType()
   }
 
   /**
@@ -292,7 +307,7 @@ class FormatLiteral extends Literal {
    * which is correct for a particular function.
    */
   Type getNonDefaultCharType() {
-    result = getUse().getTarget().(FormattingFunction).getNonDefaultCharType()
+    result = this.getUse().getTarget().(FormattingFunction).getNonDefaultCharType()
   }
 
   /**
@@ -300,7 +315,9 @@ class FormatLiteral extends Literal {
    * snapshots there may be multiple results where we can't tell which is correct for a
    * particular function.
    */
-  Type getWideCharType() { result = getUse().getTarget().(FormattingFunction).getWideCharType() }
+  Type getWideCharType() {
+    result = this.getUse().getTarget().(FormattingFunction).getWideCharType()
+  }
 
   /**
    * Holds if this `FormatLiteral` is in a context that supports
@@ -338,7 +355,7 @@ class FormatLiteral extends Literal {
   }
 
   private string getFlagRegexp() {
-    if isMicrosoft() then result = "[-+ #0']*" else result = "[-+ #0'I]*"
+    if this.isMicrosoft() then result = "[-+ #0']*" else result = "[-+ #0'I]*"
   }
 
   private string getFieldWidthRegexp() { result = "(?:[1-9][0-9]*|\\*|\\*[0-9]+\\$)?" }
@@ -346,13 +363,13 @@ class FormatLiteral extends Literal {
   private string getPrecRegexp() { result = "(?:\\.(?:[0-9]*|\\*|\\*[0-9]+\\$))?" }
 
   private string getLengthRegexp() {
-    if isMicrosoft()
+    if this.isMicrosoft()
     then result = "(?:hh?|ll?|L|q|j|z|t|w|I32|I64|I)?"
     else result = "(?:hh?|ll?|L|q|j|z|Z|t)?"
   }
 
   private string getConvCharRegexp() {
-    if isMicrosoft()
+    if this.isMicrosoft()
     then result = "[aAcCdeEfFgGimnopsSuxXZ@]"
     else result = "[aAcCdeEfFgGimnopsSuxX@]"
   }
@@ -732,16 +749,16 @@ class FormatLiteral extends Literal {
    * Gets the argument type required by the nth conversion specifier.
    */
   Type getConversionType(int n) {
-    result = getConversionType1(n) or
-    result = getConversionType1b(n) or
-    result = getConversionType2(n) or
-    result = getConversionType3(n) or
-    result = getConversionType4(n) or
-    result = getConversionType6(n) or
-    result = getConversionType7(n) or
-    result = getConversionType8(n) or
-    result = getConversionType9(n) or
-    result = getConversionType10(n)
+    result = this.getConversionType1(n) or
+    result = this.getConversionType1b(n) or
+    result = this.getConversionType2(n) or
+    result = this.getConversionType3(n) or
+    result = this.getConversionType4(n) or
+    result = this.getConversionType6(n) or
+    result = this.getConversionType7(n) or
+    result = this.getConversionType8(n) or
+    result = this.getConversionType9(n) or
+    result = this.getConversionType10(n)
   }
 
   private Type getConversionType1(int n) {
@@ -771,15 +788,15 @@ class FormatLiteral extends Literal {
         or
         conv = ["c", "C"] and
         len = ["l", "w"] and
-        result = getWideCharType()
+        result = this.getWideCharType()
         or
         conv = "c" and
         (len != "l" and len != "w" and len != "h") and
-        result = getDefaultCharType()
+        result = this.getDefaultCharType()
         or
         conv = "C" and
         (len != "l" and len != "w" and len != "h") and
-        result = getNonDefaultCharType()
+        result = this.getNonDefaultCharType()
       )
     )
   }
@@ -816,15 +833,15 @@ class FormatLiteral extends Literal {
         or
         conv = ["s", "S"] and
         len = ["l", "w"] and
-        result.(PointerType).getBaseType() = getWideCharType()
+        result.(PointerType).getBaseType() = this.getWideCharType()
         or
         conv = "s" and
         (len != "l" and len != "w" and len != "h") and
-        result.(PointerType).getBaseType() = getDefaultCharType()
+        result.(PointerType).getBaseType() = this.getDefaultCharType()
         or
         conv = "S" and
         (len != "l" and len != "w" and len != "h") and
-        result.(PointerType).getBaseType() = getNonDefaultCharType()
+        result.(PointerType).getBaseType() = this.getNonDefaultCharType()
       )
     )
   }
@@ -879,19 +896,19 @@ class FormatLiteral extends Literal {
     exists(string len, string conv |
       this.parseConvSpec(n, _, _, _, _, _, len, conv) and
       (len != "l" and len != "w" and len != "h") and
-      getUse().getTarget().(FormattingFunction).getFormatCharType().getSize() > 1 and // wide function
+      this.getUse().getTarget().(FormattingFunction).getFormatCharType().getSize() > 1 and // wide function
       (
         conv = "c" and
-        result = getNonDefaultCharType()
+        result = this.getNonDefaultCharType()
         or
         conv = "C" and
-        result = getDefaultCharType()
+        result = this.getDefaultCharType()
         or
         conv = "s" and
-        result.(PointerType).getBaseType() = getNonDefaultCharType()
+        result.(PointerType).getBaseType() = this.getNonDefaultCharType()
         or
         conv = "S" and
-        result.(PointerType).getBaseType() = getDefaultCharType()
+        result.(PointerType).getBaseType() = this.getDefaultCharType()
       )
     )
   }
@@ -924,9 +941,13 @@ class FormatLiteral extends Literal {
    * not account for positional arguments (`$`).
    */
   int getFormatArgumentIndexFor(int n, int mode) {
-    hasFormatArgumentIndexFor(n, mode) and
+    this.hasFormatArgumentIndexFor(n, mode) and
     (3 * n) + mode =
-      rank[result + 1](int n2, int mode2 | hasFormatArgumentIndexFor(n2, mode2) | (3 * n2) + mode2)
+      rank[result + 1](int n2, int mode2 |
+        this.hasFormatArgumentIndexFor(n2, mode2)
+      |
+        (3 * n2) + mode2
+      )
   }
 
   /**
@@ -936,7 +957,7 @@ class FormatLiteral extends Literal {
   int getNumArgNeeded(int n) {
     exists(this.getConvSpecOffset(n)) and
     exists(this.getConversionChar(n)) and
-    result = count(int mode | hasFormatArgumentIndexFor(n, mode))
+    result = count(int mode | this.hasFormatArgumentIndexFor(n, mode))
   }
 
   /**
@@ -948,7 +969,7 @@ class FormatLiteral extends Literal {
       // At least one conversion specifier has a parameter field, in which case,
       // they all should have.
       result = max(string s | this.getParameterField(_) = s + "$" | s.toInt())
-    else result = count(int n, int mode | hasFormatArgumentIndexFor(n, mode))
+    else result = count(int n, int mode | this.hasFormatArgumentIndexFor(n, mode))
   }
 
   /**
@@ -1038,10 +1059,10 @@ class FormatLiteral extends Literal {
         exists(int sizeBits |
           sizeBits =
             min(int bits |
-              bits = getIntegralDisplayType(n).getSize() * 8
+              bits = this.getIntegralDisplayType(n).getSize() * 8
               or
               exists(IntegralType t |
-                t = getUse().getConversionArgument(n).getType().getUnderlyingType()
+                t = this.getUse().getConversionArgument(n).getType().getUnderlyingType()
               |
                 t.isSigned() and bits = t.getSize() * 8
               )
@@ -1056,10 +1077,10 @@ class FormatLiteral extends Literal {
         exists(int sizeBits |
           sizeBits =
             min(int bits |
-              bits = getIntegralDisplayType(n).getSize() * 8
+              bits = this.getIntegralDisplayType(n).getSize() * 8
               or
               exists(IntegralType t |
-                t = getUse().getConversionArgument(n).getType().getUnderlyingType()
+                t = this.getUse().getConversionArgument(n).getType().getUnderlyingType()
               |
                 t.isUnsigned() and bits = t.getSize() * 8
               )
@@ -1074,26 +1095,26 @@ class FormatLiteral extends Literal {
         exists(int sizeBytes, int baseLen |
           sizeBytes =
             min(int bytes |
-              bytes = getIntegralDisplayType(n).getSize()
+              bytes = this.getIntegralDisplayType(n).getSize()
               or
               exists(IntegralType t |
-                t = getUse().getConversionArgument(n).getType().getUnderlyingType()
+                t = this.getUse().getConversionArgument(n).getType().getUnderlyingType()
               |
                 t.isUnsigned() and bytes = t.getSize()
               )
             ) and
           baseLen = sizeBytes * 2 and
           (
-            if hasAlternateFlag(n) then len = 2 + baseLen else len = baseLen // "0x"
+            if this.hasAlternateFlag(n) then len = 2 + baseLen else len = baseLen // "0x"
           )
         )
         or
         this.getConversionChar(n).toLowerCase() = "p" and
         exists(PointerType ptrType, int baseLen |
-          ptrType = getFullyConverted().getType() and
+          ptrType = this.getFullyConverted().getType() and
           baseLen = max(ptrType.getSize() * 2) and // e.g. "0x1234567812345678"; exact format is platform dependent
           (
-            if hasAlternateFlag(n) then len = 2 + baseLen else len = baseLen // "0x"
+            if this.hasAlternateFlag(n) then len = 2 + baseLen else len = baseLen // "0x"
           )
         )
         or
@@ -1102,17 +1123,17 @@ class FormatLiteral extends Literal {
         exists(int sizeBits, int baseLen |
           sizeBits =
             min(int bits |
-              bits = getIntegralDisplayType(n).getSize() * 8
+              bits = this.getIntegralDisplayType(n).getSize() * 8
               or
               exists(IntegralType t |
-                t = getUse().getConversionArgument(n).getType().getUnderlyingType()
+                t = this.getUse().getConversionArgument(n).getType().getUnderlyingType()
               |
                 t.isUnsigned() and bits = t.getSize() * 8
               )
             ) and
           baseLen = (sizeBits / 3.0).ceil() and
           (
-            if hasAlternateFlag(n) then len = 1 + baseLen else len = baseLen // "0"
+            if this.hasAlternateFlag(n) then len = 1 + baseLen else len = baseLen // "0"
           )
         )
         or
@@ -1135,8 +1156,8 @@ class FormatLiteral extends Literal {
    */
   int getMaxConvertedLengthLimited(int n) {
     if this.getConversionChar(n).toLowerCase() = "f"
-    then result = getMaxConvertedLength(n).minimum(8)
-    else result = getMaxConvertedLength(n)
+    then result = this.getMaxConvertedLength(n).minimum(8)
+    else result = this.getMaxConvertedLength(n)
   }
 
   /**

cpp/ql/lib/semmle/code/cpp/commons/Scanf.qll

@@ -24,7 +24,7 @@ abstract class ScanfFunction extends Function {
    * Holds if the default meaning of `%s` is a `wchar_t*` string
    * (rather than a `char*`).
    */
-  predicate isWideCharDefault() { exists(getName().indexOf("wscanf")) }
+  predicate isWideCharDefault() { exists(this.getName().indexOf("wscanf")) }
 }
 
 /**
@@ -34,10 +34,10 @@ class Scanf extends ScanfFunction {
   Scanf() {
     this instanceof TopLevelFunction and
     (
-      hasGlobalOrStdOrBslName("scanf") or // scanf(format, args...)
-      hasGlobalOrStdOrBslName("wscanf") or // wscanf(format, args...)
-      hasGlobalName("_scanf_l") or // _scanf_l(format, locale, args...)
-      hasGlobalName("_wscanf_l") // _wscanf_l(format, locale, args...)
+      this.hasGlobalOrStdOrBslName("scanf") or // scanf(format, args...)
+      this.hasGlobalOrStdOrBslName("wscanf") or // wscanf(format, args...)
+      this.hasGlobalName("_scanf_l") or // _scanf_l(format, locale, args...)
+      this.hasGlobalName("_wscanf_l") // _wscanf_l(format, locale, args...)
     )
   }
 
@@ -53,10 +53,10 @@ class Fscanf extends ScanfFunction {
   Fscanf() {
     this instanceof TopLevelFunction and
     (
-      hasGlobalOrStdOrBslName("fscanf") or // fscanf(src_stream, format, args...)
-      hasGlobalOrStdOrBslName("fwscanf") or // fwscanf(src_stream, format, args...)
-      hasGlobalName("_fscanf_l") or // _fscanf_l(src_stream, format, locale, args...)
-      hasGlobalName("_fwscanf_l") // _fwscanf_l(src_stream, format, locale, args...)
+      this.hasGlobalOrStdOrBslName("fscanf") or // fscanf(src_stream, format, args...)
+      this.hasGlobalOrStdOrBslName("fwscanf") or // fwscanf(src_stream, format, args...)
+      this.hasGlobalName("_fscanf_l") or // _fscanf_l(src_stream, format, locale, args...)
+      this.hasGlobalName("_fwscanf_l") // _fwscanf_l(src_stream, format, locale, args...)
     )
   }
 
@@ -72,10 +72,10 @@ class Sscanf extends ScanfFunction {
   Sscanf() {
     this instanceof TopLevelFunction and
     (
-      hasGlobalOrStdOrBslName("sscanf") or // sscanf(src_stream, format, args...)
-      hasGlobalOrStdOrBslName("swscanf") or // swscanf(src, format, args...)
-      hasGlobalName("_sscanf_l") or // _sscanf_l(src, format, locale, args...)
-      hasGlobalName("_swscanf_l") // _swscanf_l(src, format, locale, args...)
+      this.hasGlobalOrStdOrBslName("sscanf") or // sscanf(src_stream, format, args...)
+      this.hasGlobalOrStdOrBslName("swscanf") or // swscanf(src, format, args...)
+      this.hasGlobalName("_sscanf_l") or // _sscanf_l(src, format, locale, args...)
+      this.hasGlobalName("_swscanf_l") // _swscanf_l(src, format, locale, args...)
     )
   }
 
@@ -91,10 +91,10 @@ class Snscanf extends ScanfFunction {
   Snscanf() {
     this instanceof TopLevelFunction and
     (
-      hasGlobalName("_snscanf") or // _snscanf(src, max_amount, format, args...)
-      hasGlobalName("_snwscanf") or // _snwscanf(src, max_amount, format, args...)
-      hasGlobalName("_snscanf_l") or // _snscanf_l(src, max_amount, format, locale, args...)
-      hasGlobalName("_snwscanf_l") // _snwscanf_l(src, max_amount, format, locale, args...)
+      this.hasGlobalName("_snscanf") or // _snscanf(src, max_amount, format, args...)
+      this.hasGlobalName("_snwscanf") or // _snwscanf(src, max_amount, format, args...)
+      this.hasGlobalName("_snscanf_l") or // _snscanf_l(src, max_amount, format, locale, args...)
+      this.hasGlobalName("_snwscanf_l") // _snwscanf_l(src, max_amount, format, locale, args...)
       // note that the max_amount is not a limit on the output length, it's an input length
       // limit used with non null-terminated strings.
     )
@@ -120,18 +120,18 @@ class ScanfFunctionCall extends FunctionCall {
   /**
    * Gets the `scanf`-like function that is called.
    */
-  ScanfFunction getScanfFunction() { result = getTarget() }
+  ScanfFunction getScanfFunction() { result = this.getTarget() }
 
   /**
    * Gets the position at which the input string or stream parameter occurs,
    * if this function call does not read from standard input.
    */
-  int getInputParameterIndex() { result = getScanfFunction().getInputParameterIndex() }
+  int getInputParameterIndex() { result = this.getScanfFunction().getInputParameterIndex() }
 
   /**
    * Gets the position at which the format parameter occurs.
    */
-  int getFormatParameterIndex() { result = getScanfFunction().getFormatParameterIndex() }
+  int getFormatParameterIndex() { result = this.getScanfFunction().getFormatParameterIndex() }
 
   /**
    * Gets the format expression used in this call.
@@ -142,7 +142,7 @@ class ScanfFunctionCall extends FunctionCall {
    * Holds if the default meaning of `%s` is a `wchar_t*` string
    * (rather than a `char*`).
    */
-  predicate isWideCharDefault() { getScanfFunction().isWideCharDefault() }
+  predicate isWideCharDefault() { this.getScanfFunction().isWideCharDefault() }
 }
 
 /**
@@ -158,7 +158,7 @@ class ScanfFormatLiteral extends Expr {
   ScanfFunctionCall getUse() { result.getFormat() = this }
 
   /** Holds if the default meaning of `%s` is a `wchar_t*` (rather than a `char*`). */
-  predicate isWideCharDefault() { getUse().getTarget().(ScanfFunction).isWideCharDefault() }
+  predicate isWideCharDefault() { this.getUse().getTarget().(ScanfFunction).isWideCharDefault() }
 
   /**
    * Gets the format string itself, transformed as follows:

cpp/ql/lib/semmle/code/cpp/commons/Synchronization.qll

@@ -40,8 +40,8 @@ abstract class MutexType extends Type {
    * Gets a call that locks or tries to lock any mutex of this type.
    */
   FunctionCall getLockAccess() {
-    result = getMustlockAccess() or
-    result = getTrylockAccess()
+    result = this.getMustlockAccess() or
+    result = this.getTrylockAccess()
   }
 
   /**
@@ -63,22 +63,22 @@ abstract class MutexType extends Type {
   /**
    * DEPRECATED: use mustlockAccess(fc, arg) instead.
    */
-  deprecated Function getMustlockFunction() { result = getMustlockAccess().getTarget() }
+  deprecated Function getMustlockFunction() { result = this.getMustlockAccess().getTarget() }
 
   /**
    * DEPRECATED: use trylockAccess(fc, arg) instead.
    */
-  deprecated Function getTrylockFunction() { result = getTrylockAccess().getTarget() }
+  deprecated Function getTrylockFunction() { result = this.getTrylockAccess().getTarget() }
 
   /**
    * DEPRECATED: use lockAccess(fc, arg) instead.
    */
-  deprecated Function getLockFunction() { result = getLockAccess().getTarget() }
+  deprecated Function getLockFunction() { result = this.getLockAccess().getTarget() }
 
   /**
    * DEPRECATED: use unlockAccess(fc, arg) instead.
    */
-  deprecated Function getUnlockFunction() { result = getUnlockAccess().getTarget() }
+  deprecated Function getUnlockFunction() { result = this.getUnlockAccess().getTarget() }
 }
 
 /**
@@ -155,17 +155,17 @@ class DefaultMutexType extends MutexType {
 
   override predicate mustlockAccess(FunctionCall fc, Expr arg) {
     fc.getTarget() = mustlockCandidate() and
-    lockArgType(fc, arg)
+    this.lockArgType(fc, arg)
   }
 
   override predicate trylockAccess(FunctionCall fc, Expr arg) {
     fc.getTarget() = trylockCandidate() and
-    lockArgType(fc, arg)
+    this.lockArgType(fc, arg)
   }
 
   override predicate unlockAccess(FunctionCall fc, Expr arg) {
     fc.getTarget() = unlockCandidate() and
-    lockArgType(fc, arg)
+    this.lockArgType(fc, arg)
   }
 }
 

cpp/ql/lib/semmle/code/cpp/controlflow/BasicBlocks.qll

@@ -194,14 +194,14 @@ class BasicBlock extends ControlFlowNodeBase {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    *
    * Yields no result if this basic block spans multiple source files.
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
   ) {
-    hasLocationInfoInternal(filepath, startline, startcolumn, filepath, endline, endcolumn)
+    this.hasLocationInfoInternal(filepath, startline, startcolumn, filepath, endline, endcolumn)
   }
 
   pragma[noinline]
@@ -276,7 +276,7 @@ class EntryBasicBlock extends BasicBlock {
  */
 class ExitBasicBlock extends BasicBlock {
   ExitBasicBlock() {
-    getEnd() instanceof Function or
-    aborting(getEnd())
+    this.getEnd() instanceof Function or
+    aborting(this.getEnd())
   }
 }

cpp/ql/lib/semmle/code/cpp/controlflow/ControlFlowGraph.qll

@@ -66,7 +66,7 @@ class ControlFlowNode extends Locatable, ControlFlowNodeBase {
    */
   ControlFlowNode getATrueSuccessor() {
     qlCFGTrueSuccessor(this, result) and
-    result = getASuccessor()
+    result = this.getASuccessor()
   }
 
   /**
@@ -75,7 +75,7 @@ class ControlFlowNode extends Locatable, ControlFlowNodeBase {
    */
   ControlFlowNode getAFalseSuccessor() {
     qlCFGFalseSuccessor(this, result) and
-    result = getASuccessor()
+    result = this.getASuccessor()
   }
 
   /** Gets the `BasicBlock` containing this control-flow node. */

cpp/ql/lib/semmle/code/cpp/controlflow/IRGuards.qll

@@ -121,7 +121,7 @@ private class GuardConditionFromBinaryLogicalOperator extends GuardCondition {
 
   override predicate ensuresLt(Expr left, Expr right, int k, BasicBlock block, boolean isLessThan) {
     exists(boolean testIsTrue |
-      comparesLt(left, right, k, isLessThan, testIsTrue) and this.controls(block, testIsTrue)
+      this.comparesLt(left, right, k, isLessThan, testIsTrue) and this.controls(block, testIsTrue)
     )
   }
 
@@ -135,7 +135,7 @@ private class GuardConditionFromBinaryLogicalOperator extends GuardCondition {
 
   override predicate ensuresEq(Expr left, Expr right, int k, BasicBlock block, boolean areEqual) {
     exists(boolean testIsTrue |
-      comparesEq(left, right, k, areEqual, testIsTrue) and this.controls(block, testIsTrue)
+      this.comparesEq(left, right, k, areEqual, testIsTrue) and this.controls(block, testIsTrue)
     )
   }
 }
@@ -147,27 +147,29 @@ private class GuardConditionFromBinaryLogicalOperator extends GuardCondition {
 private class GuardConditionFromShortCircuitNot extends GuardCondition, NotExpr {
   GuardConditionFromShortCircuitNot() {
     not exists(Instruction inst | this.getFullyConverted() = inst.getAST()) and
-    exists(IRGuardCondition ir | getOperand() = ir.getAST())
+    exists(IRGuardCondition ir | this.getOperand() = ir.getAST())
   }
 
   override predicate controls(BasicBlock controlled, boolean testIsTrue) {
-    getOperand().(GuardCondition).controls(controlled, testIsTrue.booleanNot())
+    this.getOperand().(GuardCondition).controls(controlled, testIsTrue.booleanNot())
   }
 
   override predicate comparesLt(Expr left, Expr right, int k, boolean isLessThan, boolean testIsTrue) {
-    getOperand().(GuardCondition).comparesLt(left, right, k, isLessThan, testIsTrue.booleanNot())
+    this.getOperand()
+        .(GuardCondition)
+        .comparesLt(left, right, k, isLessThan, testIsTrue.booleanNot())
   }
 
   override predicate ensuresLt(Expr left, Expr right, int k, BasicBlock block, boolean isLessThan) {
-    getOperand().(GuardCondition).ensuresLt(left, right, k, block, isLessThan.booleanNot())
+    this.getOperand().(GuardCondition).ensuresLt(left, right, k, block, isLessThan.booleanNot())
   }
 
   override predicate comparesEq(Expr left, Expr right, int k, boolean areEqual, boolean testIsTrue) {
-    getOperand().(GuardCondition).comparesEq(left, right, k, areEqual, testIsTrue.booleanNot())
+    this.getOperand().(GuardCondition).comparesEq(left, right, k, areEqual, testIsTrue.booleanNot())
   }
 
   override predicate ensuresEq(Expr left, Expr right, int k, BasicBlock block, boolean areEqual) {
-    getOperand().(GuardCondition).ensuresEq(left, right, k, block, areEqual.booleanNot())
+    this.getOperand().(GuardCondition).ensuresEq(left, right, k, block, areEqual.booleanNot())
   }
 }
 
@@ -303,9 +305,9 @@ class IRGuardCondition extends Instruction {
   cached
   predicate controlsEdge(IRBlock pred, IRBlock succ, boolean testIsTrue) {
     pred.getASuccessor() = succ and
-    controls(pred, testIsTrue)
+    this.controls(pred, testIsTrue)
     or
-    succ = getBranchSuccessor(testIsTrue) and
+    succ = this.getBranchSuccessor(testIsTrue) and
     branch.getCondition() = this and
     branch.getBlock() = pred
   }

cpp/ql/lib/semmle/code/cpp/controlflow/LocalScopeVariableReachability.qll

@@ -73,19 +73,19 @@ abstract deprecated class LocalScopeVariableReachability extends string {
      */
 
     exists(BasicBlock bb, int i |
-      isSource(source, v) and
+      this.isSource(source, v) and
       bb.getNode(i) = source and
       not bb.isUnreachable()
     |
       exists(int j |
         j > i and
         sink = bb.getNode(j) and
-        isSink(sink, v) and
-        not exists(int k | isBarrier(bb.getNode(k), v) | k in [i + 1 .. j - 1])
+        this.isSink(sink, v) and
+        not exists(int k | this.isBarrier(bb.getNode(k), v) | k in [i + 1 .. j - 1])
       )
       or
-      not exists(int k | isBarrier(bb.getNode(k), v) | k > i) and
-      bbSuccessorEntryReaches(bb, v, sink, _)
+      not exists(int k | this.isBarrier(bb.getNode(k), v) | k > i) and
+      this.bbSuccessorEntryReaches(bb, v, sink, _)
     )
   }
 
@@ -97,11 +97,11 @@ abstract deprecated class LocalScopeVariableReachability extends string {
       bbSuccessorEntryReachesLoopInvariant(bb, succ, skipsFirstLoopAlwaysTrueUponEntry,
         succSkipsFirstLoopAlwaysTrueUponEntry)
     |
-      bbEntryReachesLocally(succ, v, node) and
+      this.bbEntryReachesLocally(succ, v, node) and
       succSkipsFirstLoopAlwaysTrueUponEntry = false
       or
-      not isBarrier(succ.getNode(_), v) and
-      bbSuccessorEntryReaches(succ, v, node, succSkipsFirstLoopAlwaysTrueUponEntry)
+      not this.isBarrier(succ.getNode(_), v) and
+      this.bbSuccessorEntryReaches(succ, v, node, succSkipsFirstLoopAlwaysTrueUponEntry)
     )
   }
 
@@ -110,7 +110,7 @@ abstract deprecated class LocalScopeVariableReachability extends string {
   ) {
     exists(int n |
       node = bb.getNode(n) and
-      isSink(node, v)
+      this.isSink(node, v)
     |
       not exists(this.firstBarrierIndexIn(bb, v))
       or
@@ -119,7 +119,7 @@ abstract deprecated class LocalScopeVariableReachability extends string {
   }
 
   private int firstBarrierIndexIn(BasicBlock bb, SemanticStackVariable v) {
-    result = min(int m | isBarrier(bb.getNode(m), v))
+    result = min(int m | this.isBarrier(bb.getNode(m), v))
   }
 }
 
@@ -271,7 +271,7 @@ abstract deprecated class LocalScopeVariableReachabilityWithReassignment extends
    * accounts for loops where the condition is provably true upon entry.
    */
   override predicate reaches(ControlFlowNode source, SemanticStackVariable v, ControlFlowNode sink) {
-    reachesTo(source, v, sink, _)
+    this.reachesTo(source, v, sink, _)
   }
 
   /**
@@ -281,21 +281,21 @@ abstract deprecated class LocalScopeVariableReachabilityWithReassignment extends
     ControlFlowNode source, SemanticStackVariable v, ControlFlowNode sink, SemanticStackVariable v0
   ) {
     exists(ControlFlowNode def |
-      actualSourceReaches(source, v, def, v0) and
+      this.actualSourceReaches(source, v, def, v0) and
       LocalScopeVariableReachability.super.reaches(def, v0, sink) and
-      isSinkActual(sink, v0)
+      this.isSinkActual(sink, v0)
     )
   }
 
   private predicate actualSourceReaches(
     ControlFlowNode source, SemanticStackVariable v, ControlFlowNode def, SemanticStackVariable v0
   ) {
-    isSourceActual(source, v) and def = source and v0 = v
+    this.isSourceActual(source, v) and def = source and v0 = v
     or
     exists(ControlFlowNode source1, SemanticStackVariable v1 |
-      actualSourceReaches(source, v, source1, v1)
+      this.actualSourceReaches(source, v, source1, v1)
     |
-      reassignment(source1, v1, def, v0)
+      this.reassignment(source1, v1, def, v0)
     )
   }
 
@@ -307,14 +307,14 @@ abstract deprecated class LocalScopeVariableReachabilityWithReassignment extends
   }
 
   final override predicate isSource(ControlFlowNode node, LocalScopeVariable v) {
-    isSourceActual(node, v)
+    this.isSourceActual(node, v)
     or
     // Reassignment generates a new (non-actual) source
-    reassignment(_, _, node, v)
+    this.reassignment(_, _, node, v)
   }
 
   final override predicate isSink(ControlFlowNode node, LocalScopeVariable v) {
-    isSinkActual(node, v)
+    this.isSinkActual(node, v)
     or
     // Reassignment generates a new (non-actual) sink
     exprDefinition(_, node, v.getAnAccess())
@@ -347,21 +347,21 @@ abstract deprecated class LocalScopeVariableReachabilityExt extends string {
   /** See `LocalScopeVariableReachability.reaches`. */
   predicate reaches(ControlFlowNode source, SemanticStackVariable v, ControlFlowNode sink) {
     exists(BasicBlock bb, int i |
-      isSource(source, v) and
+      this.isSource(source, v) and
       bb.getNode(i) = source and
       not bb.isUnreachable()
     |
       exists(int j |
         j > i and
         sink = bb.getNode(j) and
-        isSink(sink, v) and
-        not exists(int k | isBarrier(source, bb.getNode(k), bb.getNode(k + 1), v) |
+        this.isSink(sink, v) and
+        not exists(int k | this.isBarrier(source, bb.getNode(k), bb.getNode(k + 1), v) |
           k in [i .. j - 1]
         )
       )
       or
-      not exists(int k | isBarrier(source, bb.getNode(k), bb.getNode(k + 1), v) | k >= i) and
-      bbSuccessorEntryReaches(source, bb, v, sink, _)
+      not exists(int k | this.isBarrier(source, bb.getNode(k), bb.getNode(k + 1), v) | k >= i) and
+      this.bbSuccessorEntryReaches(source, bb, v, sink, _)
     )
   }
 
@@ -372,22 +372,22 @@ abstract deprecated class LocalScopeVariableReachabilityExt extends string {
     exists(BasicBlock succ, boolean succSkipsFirstLoopAlwaysTrueUponEntry |
       bbSuccessorEntryReachesLoopInvariant(bb, succ, skipsFirstLoopAlwaysTrueUponEntry,
         succSkipsFirstLoopAlwaysTrueUponEntry) and
-      not isBarrier(source, bb.getEnd(), succ.getStart(), v)
+      not this.isBarrier(source, bb.getEnd(), succ.getStart(), v)
     |
-      bbEntryReachesLocally(source, succ, v, node) and
+      this.bbEntryReachesLocally(source, succ, v, node) and
       succSkipsFirstLoopAlwaysTrueUponEntry = false
       or
-      not exists(int k | isBarrier(source, succ.getNode(k), succ.getNode(k + 1), v)) and
-      bbSuccessorEntryReaches(source, succ, v, node, succSkipsFirstLoopAlwaysTrueUponEntry)
+      not exists(int k | this.isBarrier(source, succ.getNode(k), succ.getNode(k + 1), v)) and
+      this.bbSuccessorEntryReaches(source, succ, v, node, succSkipsFirstLoopAlwaysTrueUponEntry)
     )
   }
 
   private predicate bbEntryReachesLocally(
     ControlFlowNode source, BasicBlock bb, SemanticStackVariable v, ControlFlowNode node
   ) {
-    isSource(source, v) and
-    exists(int n | node = bb.getNode(n) and isSink(node, v) |
-      not exists(int m | m < n | isBarrier(source, bb.getNode(m), bb.getNode(m + 1), v))
+    this.isSource(source, v) and
+    exists(int n | node = bb.getNode(n) and this.isSink(node, v) |
+      not exists(int m | m < n | this.isBarrier(source, bb.getNode(m), bb.getNode(m + 1), v))
     )
   }
 }

cpp/ql/lib/semmle/code/cpp/controlflow/SSA.qll

@@ -59,7 +59,7 @@ class SsaDefinition extends ControlFlowNodeBase {
   ControlFlowNode getDefinition() { result = this }
 
   /** Gets the `BasicBlock` containing this definition. */
-  BasicBlock getBasicBlock() { result.contains(getDefinition()) }
+  BasicBlock getBasicBlock() { result.contains(this.getDefinition()) }
 
   /** Holds if this definition is a phi node for variable `v`. */
   predicate isPhiNode(StackVariable v) { exists(StandardSSA x | x.phi_node(v, this.(BasicBlock))) }

cpp/ql/lib/semmle/code/cpp/controlflow/StackVariableReachability.qll

@@ -72,19 +72,19 @@ abstract class StackVariableReachability extends string {
      */
 
     exists(BasicBlock bb, int i |
-      isSource(source, v) and
+      this.isSource(source, v) and
       bb.getNode(i) = source and
       not bb.isUnreachable()
     |
       exists(int j |
         j > i and
         sink = bb.getNode(j) and
-        isSink(sink, v) and
-        not exists(int k | isBarrier(bb.getNode(k), v) | k in [i + 1 .. j - 1])
+        this.isSink(sink, v) and
+        not exists(int k | this.isBarrier(bb.getNode(k), v) | k in [i + 1 .. j - 1])
       )
       or
-      not exists(int k | isBarrier(bb.getNode(k), v) | k > i) and
-      bbSuccessorEntryReaches(bb, v, sink, _)
+      not exists(int k | this.isBarrier(bb.getNode(k), v) | k > i) and
+      this.bbSuccessorEntryReaches(bb, v, sink, _)
     )
   }
 
@@ -96,11 +96,11 @@ abstract class StackVariableReachability extends string {
       bbSuccessorEntryReachesLoopInvariant(bb, succ, skipsFirstLoopAlwaysTrueUponEntry,
         succSkipsFirstLoopAlwaysTrueUponEntry)
     |
-      bbEntryReachesLocally(succ, v, node) and
+      this.bbEntryReachesLocally(succ, v, node) and
       succSkipsFirstLoopAlwaysTrueUponEntry = false
       or
-      not isBarrier(succ.getNode(_), v) and
-      bbSuccessorEntryReaches(succ, v, node, succSkipsFirstLoopAlwaysTrueUponEntry)
+      not this.isBarrier(succ.getNode(_), v) and
+      this.bbSuccessorEntryReaches(succ, v, node, succSkipsFirstLoopAlwaysTrueUponEntry)
     )
   }
 
@@ -109,7 +109,7 @@ abstract class StackVariableReachability extends string {
   ) {
     exists(int n |
       node = bb.getNode(n) and
-      isSink(node, v)
+      this.isSink(node, v)
     |
       not exists(this.firstBarrierIndexIn(bb, v))
       or
@@ -118,7 +118,7 @@ abstract class StackVariableReachability extends string {
   }
 
   private int firstBarrierIndexIn(BasicBlock bb, SemanticStackVariable v) {
-    result = min(int m | isBarrier(bb.getNode(m), v))
+    result = min(int m | this.isBarrier(bb.getNode(m), v))
   }
 }
 
@@ -268,7 +268,7 @@ abstract class StackVariableReachabilityWithReassignment extends StackVariableRe
    * accounts for loops where the condition is provably true upon entry.
    */
   override predicate reaches(ControlFlowNode source, SemanticStackVariable v, ControlFlowNode sink) {
-    reachesTo(source, v, sink, _)
+    this.reachesTo(source, v, sink, _)
   }
 
   /**
@@ -278,21 +278,21 @@ abstract class StackVariableReachabilityWithReassignment extends StackVariableRe
     ControlFlowNode source, SemanticStackVariable v, ControlFlowNode sink, SemanticStackVariable v0
   ) {
     exists(ControlFlowNode def |
-      actualSourceReaches(source, v, def, v0) and
+      this.actualSourceReaches(source, v, def, v0) and
       StackVariableReachability.super.reaches(def, v0, sink) and
-      isSinkActual(sink, v0)
+      this.isSinkActual(sink, v0)
     )
   }
 
   private predicate actualSourceReaches(
     ControlFlowNode source, SemanticStackVariable v, ControlFlowNode def, SemanticStackVariable v0
   ) {
-    isSourceActual(source, v) and def = source and v0 = v
+    this.isSourceActual(source, v) and def = source and v0 = v
     or
     exists(ControlFlowNode source1, SemanticStackVariable v1 |
-      actualSourceReaches(source, v, source1, v1)
+      this.actualSourceReaches(source, v, source1, v1)
     |
-      reassignment(source1, v1, def, v0)
+      this.reassignment(source1, v1, def, v0)
     )
   }
 
@@ -304,14 +304,14 @@ abstract class StackVariableReachabilityWithReassignment extends StackVariableRe
   }
 
   final override predicate isSource(ControlFlowNode node, StackVariable v) {
-    isSourceActual(node, v)
+    this.isSourceActual(node, v)
     or
     // Reassignment generates a new (non-actual) source
-    reassignment(_, _, node, v)
+    this.reassignment(_, _, node, v)
   }
 
   final override predicate isSink(ControlFlowNode node, StackVariable v) {
-    isSinkActual(node, v)
+    this.isSinkActual(node, v)
     or
     // Reassignment generates a new (non-actual) sink
     exprDefinition(_, node, v.getAnAccess())
@@ -342,21 +342,21 @@ abstract class StackVariableReachabilityExt extends string {
   /** See `StackVariableReachability.reaches`. */
   predicate reaches(ControlFlowNode source, SemanticStackVariable v, ControlFlowNode sink) {
     exists(BasicBlock bb, int i |
-      isSource(source, v) and
+      this.isSource(source, v) and
       bb.getNode(i) = source and
       not bb.isUnreachable()
     |
       exists(int j |
         j > i and
         sink = bb.getNode(j) and
-        isSink(sink, v) and
-        not exists(int k | isBarrier(source, bb.getNode(k), bb.getNode(k + 1), v) |
+        this.isSink(sink, v) and
+        not exists(int k | this.isBarrier(source, bb.getNode(k), bb.getNode(k + 1), v) |
           k in [i .. j - 1]
         )
       )
       or
-      not exists(int k | isBarrier(source, bb.getNode(k), bb.getNode(k + 1), v) | k >= i) and
-      bbSuccessorEntryReaches(source, bb, v, sink, _)
+      not exists(int k | this.isBarrier(source, bb.getNode(k), bb.getNode(k + 1), v) | k >= i) and
+      this.bbSuccessorEntryReaches(source, bb, v, sink, _)
     )
   }
 
@@ -367,22 +367,22 @@ abstract class StackVariableReachabilityExt extends string {
     exists(BasicBlock succ, boolean succSkipsFirstLoopAlwaysTrueUponEntry |
       bbSuccessorEntryReachesLoopInvariant(bb, succ, skipsFirstLoopAlwaysTrueUponEntry,
         succSkipsFirstLoopAlwaysTrueUponEntry) and
-      not isBarrier(source, bb.getEnd(), succ.getStart(), v)
+      not this.isBarrier(source, bb.getEnd(), succ.getStart(), v)
     |
-      bbEntryReachesLocally(source, succ, v, node) and
+      this.bbEntryReachesLocally(source, succ, v, node) and
       succSkipsFirstLoopAlwaysTrueUponEntry = false
       or
-      not exists(int k | isBarrier(source, succ.getNode(k), succ.getNode(k + 1), v)) and
-      bbSuccessorEntryReaches(source, succ, v, node, succSkipsFirstLoopAlwaysTrueUponEntry)
+      not exists(int k | this.isBarrier(source, succ.getNode(k), succ.getNode(k + 1), v)) and
+      this.bbSuccessorEntryReaches(source, succ, v, node, succSkipsFirstLoopAlwaysTrueUponEntry)
     )
   }
 
   private predicate bbEntryReachesLocally(
     ControlFlowNode source, BasicBlock bb, SemanticStackVariable v, ControlFlowNode node
   ) {
-    isSource(source, v) and
-    exists(int n | node = bb.getNode(n) and isSink(node, v) |
-      not exists(int m | m < n | isBarrier(source, bb.getNode(m), bb.getNode(m + 1), v))
+    this.isSource(source, v) and
+    exists(int n | node = bb.getNode(n) and this.isSink(node, v) |
+      not exists(int m | m < n | this.isBarrier(source, bb.getNode(m), bb.getNode(m + 1), v))
     )
   }
 }

cpp/ql/lib/semmle/code/cpp/controlflow/SubBasicBlocks.qll

@@ -80,7 +80,7 @@ class SubBasicBlock extends ControlFlowNodeBase {
    * returns a 0-based position, while `getRankInBasicBlock` returns a 1-based
    * position.
    */
-  deprecated int getPosInBasicBlock(BasicBlock bb) { result = getRankInBasicBlock(bb) - 1 }
+  deprecated int getPosInBasicBlock(BasicBlock bb) { result = this.getRankInBasicBlock(bb) - 1 }
 
   pragma[noinline]
   private int getIndexInBasicBlock(BasicBlock bb) { this = bb.getNode(result) }
@@ -102,7 +102,7 @@ class SubBasicBlock extends ControlFlowNodeBase {
     exists(BasicBlock bb |
       exists(int outerIndex |
         result = bb.getNode(outerIndex) and
-        index = outerToInnerIndex(bb, outerIndex)
+        index = this.outerToInnerIndex(bb, outerIndex)
       )
     )
   }

cpp/ql/lib/semmle/code/cpp/controlflow/internal/ConstantExprs.qll

@@ -344,14 +344,13 @@ private int convertIntToType(int val, IntegralType t) {
   then if val = 0 then result = 0 else result = 1
   else
     if t.isUnsigned()
-    then if val >= 0 and val.bitShiftRight(t.getSize() * 8) = 0 then result = val else none()
+    then val >= 0 and val.bitShiftRight(t.getSize() * 8) = 0 and result = val
     else
       if val >= 0 and val.bitShiftRight(t.getSize() * 8 - 1) = 0
       then result = val
-      else
-        if (-(val + 1)).bitShiftRight(t.getSize() * 8 - 1) = 0
-        then result = val
-        else none()
+      else (
+        (-(val + 1)).bitShiftRight(t.getSize() * 8 - 1) = 0 and result = val
+      )
 }
 
 /**
@@ -386,7 +385,7 @@ library class ExprEvaluator extends int {
   abstract predicate interesting(Expr e);
 
   /** Gets the value of (interesting) expression `e`, if any. */
-  int getValue(Expr e) { result = getValueInternal(e, e) }
+  int getValue(Expr e) { result = this.getValueInternal(e, e) }
 
   /**
    * When evaluating a syntactic subexpression of `e`, we may
@@ -426,9 +425,9 @@ library class ExprEvaluator extends int {
    * calculates the values bottom-up.
    */
   predicate interestingInternal(Expr e, Expr req, boolean sub) {
-    interesting(e) and req = e and sub = true
+    this.interesting(e) and req = e and sub = true
     or
-    exists(Expr mid | interestingInternal(e, mid, sub) |
+    exists(Expr mid | this.interestingInternal(e, mid, sub) |
       req = mid.(NotExpr).getOperand() or
       req = mid.(BinaryLogicalOperation).getAnOperand() or
       req = mid.(RelationalOperation).getAnOperand() or
@@ -443,36 +442,36 @@ library class ExprEvaluator extends int {
     )
     or
     exists(VariableAccess va, Variable v, boolean sub1 |
-      interestingVariableAccess(e, va, v, sub1) and
+      this.interestingVariableAccess(e, va, v, sub1) and
       req = v.getAnAssignedValue() and
-      (sub1 = true implies not ignoreVariableAssignment(e, v, req)) and
+      (sub1 = true implies not this.ignoreVariableAssignment(e, v, req)) and
       sub = false
     )
     or
     exists(Function f |
-      interestingFunction(e, f) and
+      this.interestingFunction(e, f) and
       returnStmt(f, req) and
       sub = false
     )
   }
 
   private predicate interestingVariableAccess(Expr e, VariableAccess va, Variable v, boolean sub) {
-    interestingInternal(e, va, sub) and
+    this.interestingInternal(e, va, sub) and
     v = getVariableTarget(va) and
     (
       v.hasInitializer()
       or
-      sub = true and allowVariableWithoutInitializer(e, v)
+      sub = true and this.allowVariableWithoutInitializer(e, v)
     ) and
     tractableVariable(v) and
     forall(StmtParent def | nonAnalyzableVariableDefinition(v, def) |
       sub = true and
-      ignoreNonAnalyzableVariableDefinition(e, v, def)
+      this.ignoreNonAnalyzableVariableDefinition(e, v, def)
     )
   }
 
   private predicate interestingFunction(Expr e, Function f) {
-    exists(FunctionCall fc | interestingInternal(e, fc, _) |
+    exists(FunctionCall fc | this.interestingInternal(e, fc, _) |
       f = fc.getTarget() and
       not obviouslyNonConstant(f) and
       not f.getUnspecifiedType() instanceof VoidType
@@ -482,10 +481,10 @@ library class ExprEvaluator extends int {
   /** Gets the value of subexpressions `req` for expression `e`, if any. */
   private int getValueInternal(Expr e, Expr req) {
     (
-      interestingInternal(e, req, true) and
+      this.interestingInternal(e, req, true) and
       (
         result = req.(CompileTimeConstantInt).getIntValue() or
-        result = getCompoundValue(e, req.(CompileTimeVariableExpr))
+        result = this.getCompoundValue(e, req.(CompileTimeVariableExpr))
       ) and
       (
         req.getUnderlyingType().(IntegralType).isSigned() or
@@ -496,109 +495,126 @@ library class ExprEvaluator extends int {
 
   /** Gets the value of compound subexpressions `val` for expression `e`, if any. */
   private int getCompoundValue(Expr e, CompileTimeVariableExpr val) {
-    interestingInternal(e, val, true) and
+    this.interestingInternal(e, val, true) and
     (
       exists(NotExpr req | req = val |
-        result = 1 and getValueInternal(e, req.getOperand()) = 0
+        result = 1 and this.getValueInternal(e, req.getOperand()) = 0
         or
-        result = 0 and getValueInternal(e, req.getOperand()) != 0
+        result = 0 and this.getValueInternal(e, req.getOperand()) != 0
       )
       or
       exists(LogicalAndExpr req | req = val |
         result = 1 and
-        getValueInternal(e, req.getLeftOperand()) != 0 and
-        getValueInternal(e, req.getRightOperand()) != 0
+        this.getValueInternal(e, req.getLeftOperand()) != 0 and
+        this.getValueInternal(e, req.getRightOperand()) != 0
         or
-        result = 0 and getValueInternal(e, req.getAnOperand()) = 0
+        result = 0 and this.getValueInternal(e, req.getAnOperand()) = 0
       )
       or
       exists(LogicalOrExpr req | req = val |
-        result = 1 and getValueInternal(e, req.getAnOperand()) != 0
+        result = 1 and this.getValueInternal(e, req.getAnOperand()) != 0
         or
         result = 0 and
-        getValueInternal(e, req.getLeftOperand()) = 0 and
-        getValueInternal(e, req.getRightOperand()) = 0
+        this.getValueInternal(e, req.getLeftOperand()) = 0 and
+        this.getValueInternal(e, req.getRightOperand()) = 0
       )
       or
       exists(LTExpr req | req = val |
         result = 1 and
-        getValueInternal(e, req.getLeftOperand()) < getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) <
+          this.getValueInternal(e, req.getRightOperand())
         or
         result = 0 and
-        getValueInternal(e, req.getLeftOperand()) >= getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) >=
+          this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(GTExpr req | req = val |
         result = 1 and
-        getValueInternal(e, req.getLeftOperand()) > getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) >
+          this.getValueInternal(e, req.getRightOperand())
         or
         result = 0 and
-        getValueInternal(e, req.getLeftOperand()) <= getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) <=
+          this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(LEExpr req | req = val |
         result = 1 and
-        getValueInternal(e, req.getLeftOperand()) <= getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) <=
+          this.getValueInternal(e, req.getRightOperand())
         or
         result = 0 and
-        getValueInternal(e, req.getLeftOperand()) > getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) >
+          this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(GEExpr req | req = val |
         result = 1 and
-        getValueInternal(e, req.getLeftOperand()) >= getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) >=
+          this.getValueInternal(e, req.getRightOperand())
         or
         result = 0 and
-        getValueInternal(e, req.getLeftOperand()) < getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) <
+          this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(EQExpr req | req = val |
         result = 1 and
-        getValueInternal(e, req.getLeftOperand()) = getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) =
+          this.getValueInternal(e, req.getRightOperand())
         or
         result = 0 and
-        getValueInternal(e, req.getLeftOperand()) != getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) !=
+          this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(NEExpr req | req = val |
         result = 0 and
-        getValueInternal(e, req.getLeftOperand()) = getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) =
+          this.getValueInternal(e, req.getRightOperand())
         or
         result = 1 and
-        getValueInternal(e, req.getLeftOperand()) != getValueInternal(e, req.getRightOperand())
+        this.getValueInternal(e, req.getLeftOperand()) !=
+          this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(AddExpr req | req = val |
         result =
-          getValueInternal(e, req.getLeftOperand()) + getValueInternal(e, req.getRightOperand())
+          this.getValueInternal(e, req.getLeftOperand()) +
+            this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(SubExpr req | req = val |
         result =
-          getValueInternal(e, req.getLeftOperand()) - getValueInternal(e, req.getRightOperand())
+          this.getValueInternal(e, req.getLeftOperand()) -
+            this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(MulExpr req | req = val |
         result =
-          getValueInternal(e, req.getLeftOperand()) * getValueInternal(e, req.getRightOperand())
+          this.getValueInternal(e, req.getLeftOperand()) *
+            this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(RemExpr req | req = val |
         result =
-          getValueInternal(e, req.getLeftOperand()) % getValueInternal(e, req.getRightOperand())
+          this.getValueInternal(e, req.getLeftOperand()) %
+            this.getValueInternal(e, req.getRightOperand())
       )
       or
       exists(DivExpr req | req = val |
         result =
-          getValueInternal(e, req.getLeftOperand()) / getValueInternal(e, req.getRightOperand())
+          this.getValueInternal(e, req.getLeftOperand()) /
+            this.getValueInternal(e, req.getRightOperand())
       )
       or
-      exists(AssignExpr req | req = val | result = getValueInternal(e, req.getRValue()))
+      exists(AssignExpr req | req = val | result = this.getValueInternal(e, req.getRValue()))
       or
-      result = getVariableValue(e, val.(VariableAccess))
+      result = this.getVariableValue(e, val.(VariableAccess))
       or
       exists(FunctionCall call | call = val and not callWithMultipleTargets(call) |
-        result = getFunctionValue(call.getTarget())
+        result = this.getFunctionValue(call.getTarget())
       )
     )
   }
@@ -606,7 +622,7 @@ library class ExprEvaluator extends int {
   language[monotonicAggregates]
   private int getVariableValue(Expr e, VariableAccess va) {
     exists(Variable v |
-      interestingVariableAccess(e, va, v, true) and
+      this.interestingVariableAccess(e, va, v, true) and
       // All assignments must have the same int value
       result =
         unique(Expr value |
@@ -620,14 +636,16 @@ library class ExprEvaluator extends int {
   /** Holds if the function `f` is considered by the analysis and may return `ret`. */
   pragma[noinline]
   private predicate interestingReturnValue(Function f, Expr ret) {
-    interestingFunction(_, f) and
+    this.interestingFunction(_, f) and
     returnStmt(f, ret)
   }
 
   private int getFunctionValue(Function f) {
     // All returns must have the same int value
     // And it must have at least one return
-    forex(Expr ret | interestingReturnValue(f, ret) | result = getValueInternalNonSubExpr(ret))
+    forex(Expr ret | this.interestingReturnValue(f, ret) |
+      result = this.getValueInternalNonSubExpr(ret)
+    )
   }
 
   /**
@@ -642,10 +660,10 @@ library class ExprEvaluator extends int {
    * omitted).
    */
   private int getValueInternalNonSubExpr(Expr req) {
-    interestingInternal(_, req, false) and
+    this.interestingInternal(_, req, false) and
     (
       result = req.(CompileTimeConstantInt).getIntValue() or
-      result = getCompoundValueNonSubExpr(req.(CompileTimeVariableExpr))
+      result = this.getCompoundValueNonSubExpr(req.(CompileTimeVariableExpr))
     ) and
     (
       req.getUnderlyingType().(IntegralType).isSigned() or
@@ -656,131 +674,131 @@ library class ExprEvaluator extends int {
   private int getCompoundValueNonSubExpr(CompileTimeVariableExpr val) {
     (
       exists(NotExpr req | req = val |
-        result = 1 and getValueInternalNonSubExpr(req.getOperand()) = 0
+        result = 1 and this.getValueInternalNonSubExpr(req.getOperand()) = 0
         or
-        result = 0 and getValueInternalNonSubExpr(req.getOperand()) != 0
+        result = 0 and this.getValueInternalNonSubExpr(req.getOperand()) != 0
       )
       or
       exists(LogicalAndExpr req | req = val |
         result = 1 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) != 0 and
-        getValueInternalNonSubExpr(req.getRightOperand()) != 0
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) != 0 and
+        this.getValueInternalNonSubExpr(req.getRightOperand()) != 0
         or
-        result = 0 and getValueInternalNonSubExpr(req.getAnOperand()) = 0
+        result = 0 and this.getValueInternalNonSubExpr(req.getAnOperand()) = 0
       )
       or
       exists(LogicalOrExpr req | req = val |
-        result = 1 and getValueInternalNonSubExpr(req.getAnOperand()) != 0
+        result = 1 and this.getValueInternalNonSubExpr(req.getAnOperand()) != 0
         or
         result = 0 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) = 0 and
-        getValueInternalNonSubExpr(req.getRightOperand()) = 0
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) = 0 and
+        this.getValueInternalNonSubExpr(req.getRightOperand()) = 0
       )
       or
       exists(LTExpr req | req = val |
         result = 1 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) <
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) <
+          this.getValueInternalNonSubExpr(req.getRightOperand())
         or
         result = 0 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) >=
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) >=
+          this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(GTExpr req | req = val |
         result = 1 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) >
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) >
+          this.getValueInternalNonSubExpr(req.getRightOperand())
         or
         result = 0 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) <=
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) <=
+          this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(LEExpr req | req = val |
         result = 1 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) <=
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) <=
+          this.getValueInternalNonSubExpr(req.getRightOperand())
         or
         result = 0 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) >
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) >
+          this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(GEExpr req | req = val |
         result = 1 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) >=
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) >=
+          this.getValueInternalNonSubExpr(req.getRightOperand())
         or
         result = 0 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) <
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) <
+          this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(EQExpr req | req = val |
         result = 1 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) =
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) =
+          this.getValueInternalNonSubExpr(req.getRightOperand())
         or
         result = 0 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) !=
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) !=
+          this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(NEExpr req | req = val |
         result = 0 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) =
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) =
+          this.getValueInternalNonSubExpr(req.getRightOperand())
         or
         result = 1 and
-        getValueInternalNonSubExpr(req.getLeftOperand()) !=
-          getValueInternalNonSubExpr(req.getRightOperand())
+        this.getValueInternalNonSubExpr(req.getLeftOperand()) !=
+          this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(AddExpr req | req = val |
         result =
-          getValueInternalNonSubExpr(req.getLeftOperand()) +
-            getValueInternalNonSubExpr(req.getRightOperand())
+          this.getValueInternalNonSubExpr(req.getLeftOperand()) +
+            this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(SubExpr req | req = val |
         result =
-          getValueInternalNonSubExpr(req.getLeftOperand()) -
-            getValueInternalNonSubExpr(req.getRightOperand())
+          this.getValueInternalNonSubExpr(req.getLeftOperand()) -
+            this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(MulExpr req | req = val |
         result =
-          getValueInternalNonSubExpr(req.getLeftOperand()) *
-            getValueInternalNonSubExpr(req.getRightOperand())
+          this.getValueInternalNonSubExpr(req.getLeftOperand()) *
+            this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(RemExpr req | req = val |
         result =
-          getValueInternalNonSubExpr(req.getLeftOperand()) %
-            getValueInternalNonSubExpr(req.getRightOperand())
+          this.getValueInternalNonSubExpr(req.getLeftOperand()) %
+            this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
       exists(DivExpr req | req = val |
         result =
-          getValueInternalNonSubExpr(req.getLeftOperand()) /
-            getValueInternalNonSubExpr(req.getRightOperand())
+          this.getValueInternalNonSubExpr(req.getLeftOperand()) /
+            this.getValueInternalNonSubExpr(req.getRightOperand())
       )
       or
-      exists(AssignExpr req | req = val | result = getValueInternalNonSubExpr(req.getRValue()))
+      exists(AssignExpr req | req = val | result = this.getValueInternalNonSubExpr(req.getRValue()))
       or
-      result = getVariableValueNonSubExpr(val.(VariableAccess))
+      result = this.getVariableValueNonSubExpr(val.(VariableAccess))
       or
       exists(FunctionCall call | call = val and not callWithMultipleTargets(call) |
-        result = getFunctionValue(call.getTarget())
+        result = this.getFunctionValue(call.getTarget())
       )
     )
   }
 
   private int getVariableValueNonSubExpr(VariableAccess va) {
     // All assignments must have the same int value
-    result = getMinVariableValueNonSubExpr(va) and
-    result = getMaxVariableValueNonSubExpr(va)
+    result = this.getMinVariableValueNonSubExpr(va) and
+    result = this.getMaxVariableValueNonSubExpr(va)
   }
 
   /**
@@ -791,8 +809,9 @@ library class ExprEvaluator extends int {
   pragma[noopt]
   private int getMinVariableValueNonSubExpr(VariableAccess va) {
     exists(Variable v |
-      interestingVariableAccess(_, va, v, false) and
-      result = min(Expr value | value = v.getAnAssignedValue() | getValueInternalNonSubExpr(value))
+      this.interestingVariableAccess(_, va, v, false) and
+      result =
+        min(Expr value | value = v.getAnAssignedValue() | this.getValueInternalNonSubExpr(value))
     )
   }
 
@@ -804,8 +823,9 @@ library class ExprEvaluator extends int {
   pragma[noopt]
   private int getMaxVariableValueNonSubExpr(VariableAccess va) {
     exists(Variable v |
-      interestingVariableAccess(_, va, v, false) and
-      result = max(Expr value | value = v.getAnAssignedValue() | getValueInternalNonSubExpr(value))
+      this.interestingVariableAccess(_, va, v, false) and
+      result =
+        max(Expr value | value = v.getAnAssignedValue() | this.getValueInternalNonSubExpr(value))
     )
   }
 }
@@ -968,9 +988,9 @@ library class LoopEntryConditionEvaluator extends ExprEvaluator {
   abstract predicate isLoopBody(Expr e, StmtParent s);
 
   private predicate isLoopBodyDescendant(Expr e, StmtParent s) {
-    isLoopBody(e, s)
+    this.isLoopBody(e, s)
     or
-    exists(StmtParent mid | isLoopBodyDescendant(e, mid) |
+    exists(StmtParent mid | this.isLoopBodyDescendant(e, mid) |
       s = mid.(Stmt).getAChild() or
       s = mid.(Expr).getAChild()
     )
@@ -978,13 +998,13 @@ library class LoopEntryConditionEvaluator extends ExprEvaluator {
 
   // Same as `interestingInternal(e, sub, true)` but avoids negative recursion
   private predicate interestingSubExpr(Expr e, Expr sub) {
-    interesting(e) and e = sub
+    this.interesting(e) and e = sub
     or
-    exists(Expr mid | interestingSubExpr(e, mid) and sub = mid.getAChild())
+    exists(Expr mid | this.interestingSubExpr(e, mid) and sub = mid.getAChild())
   }
 
   private predicate maybeInterestingVariable(Expr e, Variable v) {
-    exists(VariableAccess va | interestingSubExpr(e, va) | va.getTarget() = v)
+    exists(VariableAccess va | this.interestingSubExpr(e, va) | va.getTarget() = v)
   }
 
   /**
@@ -996,9 +1016,9 @@ library class LoopEntryConditionEvaluator extends ExprEvaluator {
    * definition of `v`.
    */
   private predicate reachesLoopEntryFromLoopBody(Expr e, Variable v, StmtParent valueOrDef) {
-    maybeInterestingVariable(e, v) and
+    this.maybeInterestingVariable(e, v) and
     (valueOrDef = v.getAnAssignedValue() or nonAnalyzableVariableDefinition(v, valueOrDef)) and
-    isLoopBodyDescendant(e, valueOrDef) and
+    this.isLoopBodyDescendant(e, valueOrDef) and
     /*
      * Use primitive basic blocks in reachability analysis for better performance.
      * This is similar to the pattern used in e.g. `DefinitionsAndUses` and
@@ -1008,16 +1028,16 @@ library class LoopEntryConditionEvaluator extends ExprEvaluator {
     exists(PrimitiveBasicBlock bb1, int pos1 | bb1.getNode(pos1) = valueOrDef |
       // Reaches in same basic block
       exists(int pos2 |
-        loopEntryAt(bb1, pos2, e) and
+        this.loopEntryAt(bb1, pos2, e) and
         pos2 > pos1 and
-        not exists(int k | assignmentAt(bb1, k, v) | k in [pos1 + 1 .. pos2 - 1])
+        not exists(int k | this.assignmentAt(bb1, k, v) | k in [pos1 + 1 .. pos2 - 1])
       )
       or
       // Reaches in a successor block
       exists(PrimitiveBasicBlock bb2 |
         bb2 = bb1.getASuccessor() and
-        not exists(int pos3 | assignmentAt(bb1, pos3, v) and pos3 > pos1) and
-        bbReachesLoopEntry(bb2, e, v)
+        not exists(int pos3 | this.assignmentAt(bb1, pos3, v) and pos3 > pos1) and
+        this.bbReachesLoopEntry(bb2, e, v)
       )
     )
   }
@@ -1025,12 +1045,12 @@ library class LoopEntryConditionEvaluator extends ExprEvaluator {
   private predicate loopEntryAt(PrimitiveBasicBlock bb, int pos, Expr e) {
     exists(Node cfn |
       bb.getNode(pos) = cfn and
-      isLoopEntry(e, cfn)
+      this.isLoopEntry(e, cfn)
     )
   }
 
   private predicate assignmentAt(PrimitiveBasicBlock bb, int pos, Variable v) {
-    maybeInterestingVariable(_, v) and
+    this.maybeInterestingVariable(_, v) and
     bb.getNode(pos) = v.getAnAssignedValue()
   }
 
@@ -1039,19 +1059,19 @@ library class LoopEntryConditionEvaluator extends ExprEvaluator {
    * the loop belonging to `e` without crossing an assignment to `v`.
    */
   private predicate bbReachesLoopEntry(PrimitiveBasicBlock bb, Expr e, Variable v) {
-    bbReachesLoopEntryLocally(bb, e, v)
+    this.bbReachesLoopEntryLocally(bb, e, v)
     or
     exists(PrimitiveBasicBlock succ | succ = bb.getASuccessor() |
-      bbReachesLoopEntry(succ, e, v) and
-      not assignmentAt(bb, _, v)
+      this.bbReachesLoopEntry(succ, e, v) and
+      not this.assignmentAt(bb, _, v)
     )
   }
 
   private predicate bbReachesLoopEntryLocally(PrimitiveBasicBlock bb, Expr e, Variable v) {
     exists(int pos |
-      loopEntryAt(bb, pos, e) and
-      maybeInterestingVariable(e, v) and
-      not exists(int pos1 | assignmentAt(bb, pos1, v) | pos1 < pos)
+      this.loopEntryAt(bb, pos, e) and
+      this.maybeInterestingVariable(e, v) and
+      not exists(int pos1 | this.assignmentAt(bb, pos1, v) | pos1 < pos)
     )
   }
 
@@ -1085,10 +1105,10 @@ library class LoopEntryConditionEvaluator extends ExprEvaluator {
    * ```
    */
   override predicate ignoreNonAnalyzableVariableDefinition(Expr e, Variable v, StmtParent def) {
-    maybeInterestingVariable(e, v) and
+    this.maybeInterestingVariable(e, v) and
     nonAnalyzableVariableDefinition(v, def) and
-    isLoopBodyDescendant(e, def) and
-    not reachesLoopEntryFromLoopBody(e, v, def)
+    this.isLoopBodyDescendant(e, def) and
+    not this.reachesLoopEntryFromLoopBody(e, v, def)
   }
 
   /**
@@ -1121,10 +1141,10 @@ library class LoopEntryConditionEvaluator extends ExprEvaluator {
    * ```
    */
   override predicate ignoreVariableAssignment(Expr e, Variable v, Expr value) {
-    maybeInterestingVariable(e, v) and
+    this.maybeInterestingVariable(e, v) and
     value = v.getAnAssignedValue() and
-    isLoopBodyDescendant(e, value) and
-    not reachesLoopEntryFromLoopBody(e, v, value)
+    this.isLoopBodyDescendant(e, value) and
+    not this.reachesLoopEntryFromLoopBody(e, v, value)
   }
 }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl3.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl4.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImplCommon.qll

@@ -786,16 +786,24 @@ private module Cached {
   }
 
   /**
-   * Holds if the call context `call` either improves virtual dispatch in
-   * `callable` or if it allows us to prune unreachable nodes in `callable`.
+   * Holds if the call context `call` improves virtual dispatch in `callable`.
    */
   cached
-  predicate recordDataFlowCallSite(DataFlowCall call, DataFlowCallable callable) {
+  predicate recordDataFlowCallSiteDispatch(DataFlowCall call, DataFlowCallable callable) {
     reducedViableImplInCallContext(_, callable, call)
-    or
+  }
+
+  /**
+   * Holds if the call context `call` allows us to prune unreachable nodes in `callable`.
+   */
+  cached
+  predicate recordDataFlowCallSiteUnreachable(DataFlowCall call, DataFlowCallable callable) {
     exists(Node n | getNodeEnclosingCallable(n) = callable | isUnreachableInCallCached(n, call))
   }
 
+  cached
+  predicate allowParameterReturnInSelfCached(ParamNode p) { allowParameterReturnInSelf(p) }
+
   cached
   newtype TCallContext =
     TAnyCallContext() or
@@ -846,6 +854,15 @@ private module Cached {
     TAccessPathFrontSome(AccessPathFront apf)
 }
 
+/**
+ * Holds if the call context `call` either improves virtual dispatch in
+ * `callable` or if it allows us to prune unreachable nodes in `callable`.
+ */
+predicate recordDataFlowCallSite(DataFlowCall call, DataFlowCallable callable) {
+  recordDataFlowCallSiteDispatch(call, callable) or
+  recordDataFlowCallSiteUnreachable(call, callable)
+}
+
 /**
  * A `Node` at which a cast can occur such that the type should be checked.
  */
@@ -923,7 +940,7 @@ class CallContextSpecificCall extends CallContextCall, TSpecificCall {
   }
 
   override predicate relevantFor(DataFlowCallable callable) {
-    recordDataFlowCallSite(getCall(), callable)
+    recordDataFlowCallSite(this.getCall(), callable)
   }
 
   override predicate matchesCall(DataFlowCall call) { call = this.getCall() }
@@ -1222,6 +1239,13 @@ class TypedContent extends MkTypedContent {
 
   /** Gets a textual representation of this content. */
   string toString() { result = c.toString() }
+
+  /**
+   * Holds if access paths with this `TypedContent` at their head always should
+   * be tracked at high precision. This disables adaptive access path precision
+   * for such access paths.
+   */
+  predicate forceHighPrecision() { forceHighPrecision(c) }
 }
 
 /**
@@ -1236,7 +1260,7 @@ abstract class AccessPathFront extends TAccessPathFront {
 
   TypedContent getHead() { this = TFrontHead(result) }
 
-  predicate isClearedAt(Node n) { clearsContentCached(n, getHead().getContent()) }
+  predicate isClearedAt(Node n) { clearsContentCached(n, this.getHead().getContent()) }
 }
 
 class AccessPathFrontNil extends AccessPathFront, TFrontNil {

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImplConsistency.qll

@@ -175,6 +175,7 @@ module Consistency {
 
   query predicate postWithInFlow(Node n, string msg) {
     isPostUpdateNode(n) and
+    not clearsContent(n, _) and
     simpleLocalFlowStep(_, n) and
     msg = "PostUpdateNode should not be the target of local flow."
   }

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImplLocal.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowPrivate.qll

@@ -219,15 +219,13 @@ class DataFlowExpr = Expr;
 class DataFlowType = Type;
 
 /** A function call relevant for data flow. */
-class DataFlowCall extends Expr {
-  DataFlowCall() { this instanceof Call }
-
+class DataFlowCall extends Expr instanceof Call {
   /**
    * Gets the nth argument for this call.
    *
    * The range of `n` is from `0` to `getNumberOfArguments() - 1`.
    */
-  Expr getArgument(int n) { result = this.(Call).getArgument(n) }
+  Expr getArgument(int n) { result = super.getArgument(n) }
 
   /** Gets the data flow node corresponding to this call. */
   ExprNode getNode() { result.getExpr() = this }
@@ -240,6 +238,12 @@ predicate isUnreachableInCall(Node n, DataFlowCall call) { none() } // stub impl
 
 int accessPathLimit() { result = 5 }
 
+/**
+ * Holds if access paths with `c` at their head always should be tracked at high
+ * precision. This disables adaptive access path precision for such access paths.
+ */
+predicate forceHighPrecision(Content c) { none() }
+
 /** The unit type. */
 private newtype TUnit = TMkUnit()
 
@@ -283,3 +287,12 @@ predicate lambdaCall(DataFlowCall call, LambdaCallKind kind, Node receiver) { no
 
 /** Extra data-flow steps needed for lambda flow analysis. */
 predicate additionalLambdaFlowStep(Node nodeFrom, Node nodeTo, boolean preservesValue) { none() }
+
+/**
+ * Holds if flow is allowed to pass from parameter `p` and back to itself as a
+ * side-effect, resulting in a summary from `p` to itself.
+ *
+ * One example would be to allow flow like `p.foo = p.bar;`, which is disallowed
+ * by default as a heuristic.
+ */
+predicate allowParameterReturnInSelf(ParameterNode p) { none() }

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll

@@ -101,18 +101,18 @@ class Node extends TNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
   ) {
-    getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
+    this.getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
   }
 
   /**
    * Gets an upper bound on the type of this node.
    */
-  Type getTypeBound() { result = getType() }
+  Type getTypeBound() { result = this.getType() }
 }
 
 /**
@@ -293,11 +293,11 @@ abstract class PostUpdateNode extends Node {
    */
   abstract Node getPreUpdateNode();
 
-  override Function getFunction() { result = getPreUpdateNode().getFunction() }
+  override Function getFunction() { result = this.getPreUpdateNode().getFunction() }
 
-  override Type getType() { result = getPreUpdateNode().getType() }
+  override Type getType() { result = this.getPreUpdateNode().getType() }
 
-  override Location getLocation() { result = getPreUpdateNode().getLocation() }
+  override Location getLocation() { result = this.getPreUpdateNode().getLocation() }
 }
 
 abstract private class PartialDefinitionNode extends PostUpdateNode, TPartialDefinitionNode {
@@ -309,7 +309,7 @@ abstract private class PartialDefinitionNode extends PostUpdateNode, TPartialDef
 
   PartialDefinition getPartialDefinition() { result = pd }
 
-  override string toString() { result = getPreUpdateNode().toString() + " [post update]" }
+  override string toString() { result = this.getPreUpdateNode().toString() + " [post update]" }
 }
 
 private class VariablePartialDefinitionNode extends PartialDefinitionNode {
@@ -380,13 +380,13 @@ private class ObjectInitializerNode extends PostUpdateNode, TExprNode {
 class PreObjectInitializerNode extends Node, TPreObjectInitializerNode {
   Expr getExpr() { this = TPreObjectInitializerNode(result) }
 
-  override Function getFunction() { result = getExpr().getEnclosingFunction() }
+  override Function getFunction() { result = this.getExpr().getEnclosingFunction() }
 
-  override Type getType() { result = getExpr().getType() }
+  override Type getType() { result = this.getExpr().getType() }
 
-  override Location getLocation() { result = getExpr().getLocation() }
+  override Location getLocation() { result = this.getExpr().getLocation() }
 
-  override string toString() { result = getExpr().toString() + " [pre init]" }
+  override string toString() { result = this.getExpr().toString() + " [pre init]" }
 }
 
 /**
@@ -401,7 +401,7 @@ private class PostConstructorInitThis extends PostUpdateNode, TPostConstructorIn
   }
 
   override string toString() {
-    result = getPreUpdateNode().getConstructorFieldInit().toString() + " [post-this]"
+    result = this.getPreUpdateNode().getConstructorFieldInit().toString() + " [post-this]"
   }
 }
 
@@ -416,15 +416,17 @@ private class PostConstructorInitThis extends PostUpdateNode, TPostConstructorIn
 class PreConstructorInitThis extends Node, TPreConstructorInitThis {
   ConstructorFieldInit getConstructorFieldInit() { this = TPreConstructorInitThis(result) }
 
-  override Constructor getFunction() { result = getConstructorFieldInit().getEnclosingFunction() }
-
-  override PointerType getType() {
-    result.getBaseType() = getConstructorFieldInit().getEnclosingFunction().getDeclaringType()
+  override Constructor getFunction() {
+    result = this.getConstructorFieldInit().getEnclosingFunction()
   }
 
-  override Location getLocation() { result = getConstructorFieldInit().getLocation() }
+  override PointerType getType() {
+    result.getBaseType() = this.getConstructorFieldInit().getEnclosingFunction().getDeclaringType()
+  }
 
-  override string toString() { result = getConstructorFieldInit().toString() + " [pre-this]" }
+  override Location getLocation() { result = this.getConstructorFieldInit().getLocation() }
+
+  override string toString() { result = this.getConstructorFieldInit().toString() + " [pre-this]" }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/dataflow/internal/FlowVar.qll

@@ -354,7 +354,7 @@ module FlowVar_internal {
         result = def.getAUse(v)
         or
         exists(SsaDefinition descendentDef |
-          getASuccessorSsaVar+() = TSsaVar(descendentDef, _) and
+          this.getASuccessorSsaVar+() = TSsaVar(descendentDef, _) and
           result = descendentDef.getAUse(v)
         )
       )
@@ -515,7 +515,7 @@ module FlowVar_internal {
       this.bbInLoopCondition(bbInside) and
       not this.bbInLoop(bbOutside) and
       bbOutside = bbInside.getASuccessor() and
-      not reachesWithoutAssignment(bbInside, v)
+      not this.reachesWithoutAssignment(bbInside, v)
     }
 
     /**
@@ -546,7 +546,7 @@ module FlowVar_internal {
     private predicate bbInLoop(BasicBlock bb) {
       bbDominates(this.(Loop).getStmt(), bb)
       or
-      bbInLoopCondition(bb)
+      this.bbInLoopCondition(bb)
     }
 
     /** Holds if `sbb` is inside this loop. */
@@ -563,7 +563,7 @@ module FlowVar_internal {
         bb = this.(Loop).getStmt() and
         v = this.getARelevantVariable()
         or
-        reachesWithoutAssignment(bb.getAPredecessor(), v) and
+        this.reachesWithoutAssignment(bb.getAPredecessor(), v) and
         this.bbInLoop(bb)
       ) and
       not assignsToVar(bb, v)

cpp/ql/lib/semmle/code/cpp/dataflow/internal/SubBasicBlocks.qll

@@ -80,7 +80,7 @@ class SubBasicBlock extends ControlFlowNodeBase {
    * returns a 0-based position, while `getRankInBasicBlock` returns a 1-based
    * position.
    */
-  deprecated int getPosInBasicBlock(BasicBlock bb) { result = getRankInBasicBlock(bb) - 1 }
+  deprecated int getPosInBasicBlock(BasicBlock bb) { result = this.getRankInBasicBlock(bb) - 1 }
 
   pragma[noinline]
   private int getIndexInBasicBlock(BasicBlock bb) { this = bb.getNode(result) }
@@ -102,7 +102,7 @@ class SubBasicBlock extends ControlFlowNodeBase {
     exists(BasicBlock bb |
       exists(int outerIndex |
         result = bb.getNode(outerIndex) and
-        index = outerToInnerIndex(bb, outerIndex)
+        index = this.outerToInnerIndex(bb, outerIndex)
       )
     )
   }

cpp/ql/lib/semmle/code/cpp/dataflow/internal/tainttracking1/TaintTrackingImpl.qll

@@ -75,24 +75,26 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isSanitizer(DataFlow::Node node) { none() }
 
   final override predicate isBarrier(DataFlow::Node node) {
-    isSanitizer(node) or
+    this.isSanitizer(node) or
     defaultTaintSanitizer(node)
   }
 
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierIn(DataFlow::Node node) { isSanitizerIn(node) }
+  final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
   predicate isSanitizerOut(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierOut(DataFlow::Node node) { isSanitizerOut(node) }
+  final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) { isSanitizerGuard(guard) }
+  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
+  }
 
   /**
    * Holds if the additional taint propagation step from `node1` to `node2`
@@ -101,7 +103,7 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isAdditionalTaintStep(DataFlow::Node node1, DataFlow::Node node2) { none() }
 
   final override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
-    isAdditionalTaintStep(node1, node2) or
+    this.isAdditionalTaintStep(node1, node2) or
     defaultAdditionalTaintStep(node1, node2)
   }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/tainttracking2/TaintTrackingImpl.qll

@@ -75,24 +75,26 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isSanitizer(DataFlow::Node node) { none() }
 
   final override predicate isBarrier(DataFlow::Node node) {
-    isSanitizer(node) or
+    this.isSanitizer(node) or
     defaultTaintSanitizer(node)
   }
 
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierIn(DataFlow::Node node) { isSanitizerIn(node) }
+  final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
   predicate isSanitizerOut(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierOut(DataFlow::Node node) { isSanitizerOut(node) }
+  final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) { isSanitizerGuard(guard) }
+  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
+  }
 
   /**
    * Holds if the additional taint propagation step from `node1` to `node2`
@@ -101,7 +103,7 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isAdditionalTaintStep(DataFlow::Node node1, DataFlow::Node node2) { none() }
 
   final override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
-    isAdditionalTaintStep(node1, node2) or
+    this.isAdditionalTaintStep(node1, node2) or
     defaultAdditionalTaintStep(node1, node2)
   }
 

cpp/ql/lib/semmle/code/cpp/exprs/Access.qll

@@ -203,7 +203,7 @@ class PointerFieldAccess extends FieldAccess {
 
   PointerFieldAccess() {
     exists(PointerType t |
-      t = getQualifier().getFullyConverted().getUnspecifiedType() and
+      t = this.getQualifier().getFullyConverted().getUnspecifiedType() and
       t.getBaseType() instanceof Class
     )
   }
@@ -218,7 +218,9 @@ class PointerFieldAccess extends FieldAccess {
 class DotFieldAccess extends FieldAccess {
   override string getAPrimaryQlClass() { result = "DotFieldAccess" }
 
-  DotFieldAccess() { exists(Class c | c = getQualifier().getFullyConverted().getUnspecifiedType()) }
+  DotFieldAccess() {
+    exists(Class c | c = this.getQualifier().getFullyConverted().getUnspecifiedType())
+  }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/exprs/ArithmeticOperation.qll

@@ -148,7 +148,7 @@ class PostfixIncrExpr extends IncrementOperation, PostfixCrementOperation, @post
 
   override int getPrecedence() { result = 17 }
 
-  override string toString() { result = "... " + getOperator() }
+  override string toString() { result = "... " + this.getOperator() }
 }
 
 /**
@@ -166,7 +166,7 @@ class PostfixDecrExpr extends DecrementOperation, PostfixCrementOperation, @post
 
   override int getPrecedence() { result = 17 }
 
-  override string toString() { result = "... " + getOperator() }
+  override string toString() { result = "... " + this.getOperator() }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/exprs/BuiltInOperations.qll

@@ -35,12 +35,12 @@ class BuiltInVarArgsStart extends VarArgsExpr, @vastartexpr {
   /**
    * Gets the `va_list` argument.
    */
-  final Expr getVAList() { result = getChild(0) }
+  final Expr getVAList() { result = this.getChild(0) }
 
   /**
    * Gets the argument that specifies the last named parameter before the ellipsis.
    */
-  final VariableAccess getLastNamedParameter() { result = getChild(1) }
+  final VariableAccess getLastNamedParameter() { result = this.getChild(1) }
 }
 
 /**
@@ -60,7 +60,7 @@ class BuiltInVarArgsEnd extends VarArgsExpr, @vaendexpr {
   /**
    * Gets the `va_list` argument.
    */
-  final Expr getVAList() { result = getChild(0) }
+  final Expr getVAList() { result = this.getChild(0) }
 }
 
 /**
@@ -78,7 +78,7 @@ class BuiltInVarArg extends VarArgsExpr, @vaargexpr {
   /**
    * Gets the `va_list` argument.
    */
-  final Expr getVAList() { result = getChild(0) }
+  final Expr getVAList() { result = this.getChild(0) }
 }
 
 /**
@@ -98,12 +98,12 @@ class BuiltInVarArgCopy extends VarArgsExpr, @vacopyexpr {
   /**
    * Gets the destination `va_list` argument.
    */
-  final Expr getDestinationVAList() { result = getChild(0) }
+  final Expr getDestinationVAList() { result = this.getChild(0) }
 
   /**
    * Gets the the source `va_list` argument.
    */
-  final Expr getSourceVAList() { result = getChild(1) }
+  final Expr getSourceVAList() { result = this.getChild(1) }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/exprs/Call.qll

@@ -71,10 +71,10 @@ class Call extends Expr, NameQualifiableElement, TCall {
    * at index 2, respectively.
    */
   Expr getAnArgumentSubExpr(int index) {
-    result = getArgument(index)
+    result = this.getArgument(index)
     or
     exists(Expr mid |
-      mid = getAnArgumentSubExpr(index) and
+      mid = this.getAnArgumentSubExpr(index) and
       not mid instanceof Call and
       not mid instanceof SizeofOperator and
       result = mid.getAChild()
@@ -167,27 +167,27 @@ class FunctionCall extends Call, @funbindexpr {
   override string getAPrimaryQlClass() { result = "FunctionCall" }
 
   /** Gets an explicit template argument for this call. */
-  Locatable getAnExplicitTemplateArgument() { result = getExplicitTemplateArgument(_) }
+  Locatable getAnExplicitTemplateArgument() { result = this.getExplicitTemplateArgument(_) }
 
   /** Gets an explicit template argument value for this call. */
-  Locatable getAnExplicitTemplateArgumentKind() { result = getExplicitTemplateArgumentKind(_) }
+  Locatable getAnExplicitTemplateArgumentKind() { result = this.getExplicitTemplateArgumentKind(_) }
 
   /** Gets a template argument for this call. */
-  Locatable getATemplateArgument() { result = getTarget().getATemplateArgument() }
+  Locatable getATemplateArgument() { result = this.getTarget().getATemplateArgument() }
 
   /** Gets a template argument value for this call. */
-  Locatable getATemplateArgumentKind() { result = getTarget().getATemplateArgumentKind() }
+  Locatable getATemplateArgumentKind() { result = this.getTarget().getATemplateArgumentKind() }
 
   /** Gets the nth explicit template argument for this call. */
   Locatable getExplicitTemplateArgument(int n) {
-    n < getNumberOfExplicitTemplateArguments() and
-    result = getTemplateArgument(n)
+    n < this.getNumberOfExplicitTemplateArguments() and
+    result = this.getTemplateArgument(n)
   }
 
   /** Gets the nth explicit template argument value for this call. */
   Locatable getExplicitTemplateArgumentKind(int n) {
-    n < getNumberOfExplicitTemplateArguments() and
-    result = getTemplateArgumentKind(n)
+    n < this.getNumberOfExplicitTemplateArguments() and
+    result = this.getTemplateArgumentKind(n)
   }
 
   /** Gets the number of explicit template arguments for this call. */
@@ -198,19 +198,19 @@ class FunctionCall extends Call, @funbindexpr {
   }
 
   /** Gets the number of template arguments for this call. */
-  int getNumberOfTemplateArguments() { result = count(int i | exists(getTemplateArgument(i))) }
+  int getNumberOfTemplateArguments() { result = count(int i | exists(this.getTemplateArgument(i))) }
 
   /** Gets the nth template argument for this call (indexed from 0). */
-  Locatable getTemplateArgument(int n) { result = getTarget().getTemplateArgument(n) }
+  Locatable getTemplateArgument(int n) { result = this.getTarget().getTemplateArgument(n) }
 
   /** Gets the nth template argument value for this call (indexed from 0). */
-  Locatable getTemplateArgumentKind(int n) { result = getTarget().getTemplateArgumentKind(n) }
+  Locatable getTemplateArgumentKind(int n) { result = this.getTarget().getTemplateArgumentKind(n) }
 
   /** Holds if any template arguments for this call are implicit / deduced. */
   predicate hasImplicitTemplateArguments() {
     exists(int i |
-      exists(getTemplateArgument(i)) and
-      not exists(getExplicitTemplateArgument(i))
+      exists(this.getTemplateArgument(i)) and
+      not exists(this.getExplicitTemplateArgument(i))
     )
   }
 
@@ -233,9 +233,9 @@ class FunctionCall extends Call, @funbindexpr {
    * visible at the call site.
    */
   Type getExpectedReturnType() {
-    if getTargetType() instanceof RoutineType
-    then result = getTargetType().(RoutineType).getReturnType()
-    else result = getTarget().getType()
+    if this.getTargetType() instanceof RoutineType
+    then result = this.getTargetType().(RoutineType).getReturnType()
+    else result = this.getTarget().getType()
   }
 
   /**
@@ -247,9 +247,9 @@ class FunctionCall extends Call, @funbindexpr {
    * was visible at the call site.
    */
   Type getExpectedParameterType(int n) {
-    if getTargetType() instanceof RoutineType
-    then result = getTargetType().(RoutineType).getParameterType(n)
-    else result = getTarget().getParameter(n).getType()
+    if this.getTargetType() instanceof RoutineType
+    then result = this.getTargetType().(RoutineType).getParameterType(n)
+    else result = this.getTarget().getParameter(n).getType()
   }
 
   /**
@@ -263,7 +263,7 @@ class FunctionCall extends Call, @funbindexpr {
   /**
    * Gets the type of this expression, that is, the return type of the function being called.
    */
-  override Type getType() { result = getExpectedReturnType() }
+  override Type getType() { result = this.getExpectedReturnType() }
 
   /**
    * Holds if this is a call to a virtual function.
@@ -280,7 +280,7 @@ class FunctionCall extends Call, @funbindexpr {
 
   /** Gets a textual representation of this function call. */
   override string toString() {
-    if exists(getTarget())
+    if exists(this.getTarget())
     then result = "call to " + this.getTarget().getName()
     else result = "call to unknown function"
   }
@@ -288,15 +288,15 @@ class FunctionCall extends Call, @funbindexpr {
   override predicate mayBeImpure() {
     this.getChild(_).mayBeImpure() or
     this.getTarget().mayHaveSideEffects() or
-    isVirtual() or
-    getTarget().getAnAttribute().getName() = "weak"
+    this.isVirtual() or
+    this.getTarget().getAnAttribute().getName() = "weak"
   }
 
   override predicate mayBeGloballyImpure() {
     this.getChild(_).mayBeGloballyImpure() or
     this.getTarget().mayHaveSideEffects() or
-    isVirtual() or
-    getTarget().getAnAttribute().getName() = "weak"
+    this.isVirtual() or
+    this.getTarget().getAnAttribute().getName() = "weak"
   }
 }
 
@@ -367,7 +367,7 @@ class OverloadedPointerDereferenceExpr extends FunctionCall {
  * ```
  */
 class OverloadedArrayExpr extends FunctionCall {
-  OverloadedArrayExpr() { getTarget().hasName("operator[]") }
+  OverloadedArrayExpr() { this.getTarget().hasName("operator[]") }
 
   override string getAPrimaryQlClass() { result = "OverloadedArrayExpr" }
 
@@ -585,7 +585,7 @@ class ConstructorFieldInit extends ConstructorInit, @ctorfieldinit {
    */
   Expr getExpr() { result = this.getChild(0) }
 
-  override string toString() { result = "constructor init of field " + getTarget().getName() }
+  override string toString() { result = "constructor init of field " + this.getTarget().getName() }
 
   override predicate mayBeImpure() { this.getExpr().mayBeImpure() }
 

cpp/ql/lib/semmle/code/cpp/exprs/Cast.qll

@@ -188,8 +188,8 @@ private predicate isPointerToMemberOrNullPointer(Type type) {
 class ArithmeticConversion extends Cast {
   ArithmeticConversion() {
     conversionkinds(underlyingElement(this), 0) and
-    isArithmeticOrEnum(getUnspecifiedType()) and
-    isArithmeticOrEnum(getExpr().getUnspecifiedType())
+    isArithmeticOrEnum(this.getUnspecifiedType()) and
+    isArithmeticOrEnum(this.getExpr().getUnspecifiedType())
   }
 
   override string getSemanticConversionString() { result = "arithmetic conversion" }
@@ -204,8 +204,8 @@ class ArithmeticConversion extends Cast {
  */
 class IntegralConversion extends ArithmeticConversion {
   IntegralConversion() {
-    isIntegralOrEnum(getUnspecifiedType()) and
-    isIntegralOrEnum(getExpr().getUnspecifiedType())
+    isIntegralOrEnum(this.getUnspecifiedType()) and
+    isIntegralOrEnum(this.getExpr().getUnspecifiedType())
   }
 
   override string getAPrimaryQlClass() {
@@ -224,8 +224,8 @@ class IntegralConversion extends ArithmeticConversion {
  */
 class FloatingPointConversion extends ArithmeticConversion {
   FloatingPointConversion() {
-    getUnspecifiedType() instanceof FloatingPointType and
-    getExpr().getUnspecifiedType() instanceof FloatingPointType
+    this.getUnspecifiedType() instanceof FloatingPointType and
+    this.getExpr().getUnspecifiedType() instanceof FloatingPointType
   }
 
   override string getAPrimaryQlClass() {
@@ -244,8 +244,8 @@ class FloatingPointConversion extends ArithmeticConversion {
  */
 class FloatingPointToIntegralConversion extends ArithmeticConversion {
   FloatingPointToIntegralConversion() {
-    isIntegralOrEnum(getUnspecifiedType()) and
-    getExpr().getUnspecifiedType() instanceof FloatingPointType
+    isIntegralOrEnum(this.getUnspecifiedType()) and
+    this.getExpr().getUnspecifiedType() instanceof FloatingPointType
   }
 
   override string getAPrimaryQlClass() {
@@ -264,8 +264,8 @@ class FloatingPointToIntegralConversion extends ArithmeticConversion {
  */
 class IntegralToFloatingPointConversion extends ArithmeticConversion {
   IntegralToFloatingPointConversion() {
-    getUnspecifiedType() instanceof FloatingPointType and
-    isIntegralOrEnum(getExpr().getUnspecifiedType())
+    this.getUnspecifiedType() instanceof FloatingPointType and
+    isIntegralOrEnum(this.getExpr().getUnspecifiedType())
   }
 
   override string getAPrimaryQlClass() {
@@ -290,8 +290,8 @@ class IntegralToFloatingPointConversion extends ArithmeticConversion {
 class PointerConversion extends Cast {
   PointerConversion() {
     conversionkinds(underlyingElement(this), 0) and
-    isPointerOrNullPointer(getUnspecifiedType()) and
-    isPointerOrNullPointer(getExpr().getUnspecifiedType())
+    isPointerOrNullPointer(this.getUnspecifiedType()) and
+    isPointerOrNullPointer(this.getExpr().getUnspecifiedType())
   }
 
   override string getAPrimaryQlClass() { not exists(qlCast(this)) and result = "PointerConversion" }
@@ -315,8 +315,8 @@ class PointerToMemberConversion extends Cast {
   PointerToMemberConversion() {
     conversionkinds(underlyingElement(this), 0) and
     exists(Type fromType, Type toType |
-      fromType = getExpr().getUnspecifiedType() and
-      toType = getUnspecifiedType() and
+      fromType = this.getExpr().getUnspecifiedType() and
+      toType = this.getUnspecifiedType() and
       isPointerToMemberOrNullPointer(fromType) and
       isPointerToMemberOrNullPointer(toType) and
       // A conversion from nullptr to nullptr is a `PointerConversion`, not a
@@ -345,8 +345,8 @@ class PointerToMemberConversion extends Cast {
 class PointerToIntegralConversion extends Cast {
   PointerToIntegralConversion() {
     conversionkinds(underlyingElement(this), 0) and
-    isIntegralOrEnum(getUnspecifiedType()) and
-    isPointerOrNullPointer(getExpr().getUnspecifiedType())
+    isIntegralOrEnum(this.getUnspecifiedType()) and
+    isPointerOrNullPointer(this.getExpr().getUnspecifiedType())
   }
 
   override string getAPrimaryQlClass() {
@@ -366,8 +366,8 @@ class PointerToIntegralConversion extends Cast {
 class IntegralToPointerConversion extends Cast {
   IntegralToPointerConversion() {
     conversionkinds(underlyingElement(this), 0) and
-    isPointerOrNullPointer(getUnspecifiedType()) and
-    isIntegralOrEnum(getExpr().getUnspecifiedType())
+    isPointerOrNullPointer(this.getUnspecifiedType()) and
+    isIntegralOrEnum(this.getExpr().getUnspecifiedType())
   }
 
   override string getAPrimaryQlClass() {
@@ -403,7 +403,7 @@ class BoolConversion extends Cast {
 class VoidConversion extends Cast {
   VoidConversion() {
     conversionkinds(underlyingElement(this), 0) and
-    getUnspecifiedType() instanceof VoidType
+    this.getUnspecifiedType() instanceof VoidType
   }
 
   override string getAPrimaryQlClass() { not exists(qlCast(this)) and result = "VoidConversion" }
@@ -434,8 +434,8 @@ class InheritanceConversion extends Cast {
    * conversion is to an indirect virtual base class.
    */
   final ClassDerivation getDerivation() {
-    result.getBaseClass() = getBaseClass() and
-    result.getDerivedClass() = getDerivedClass()
+    result.getBaseClass() = this.getBaseClass() and
+    result.getDerivedClass() = this.getDerivedClass()
   }
 
   /**
@@ -490,12 +490,12 @@ class BaseClassConversion extends InheritanceConversion {
 
   override Class getBaseClass() { result = getConversionClass(this) }
 
-  override Class getDerivedClass() { result = getConversionClass(getExpr()) }
+  override Class getDerivedClass() { result = getConversionClass(this.getExpr()) }
 
   /**
    * Holds if this conversion is to a virtual base class.
    */
-  predicate isVirtual() { getDerivation().isVirtual() or not exists(getDerivation()) }
+  predicate isVirtual() { this.getDerivation().isVirtual() or not exists(this.getDerivation()) }
 }
 
 /**
@@ -515,7 +515,7 @@ class DerivedClassConversion extends InheritanceConversion {
 
   override string getSemanticConversionString() { result = "derived class conversion" }
 
-  override Class getBaseClass() { result = getConversionClass(getExpr()) }
+  override Class getBaseClass() { result = getConversionClass(this.getExpr()) }
 
   override Class getDerivedClass() { result = getConversionClass(this) }
 }
@@ -637,8 +637,8 @@ class DynamicCast extends Cast, @dynamic_cast {
  */
 class UuidofOperator extends Expr, @uuidof {
   override string toString() {
-    if exists(getTypeOperand())
-    then result = "__uuidof(" + getTypeOperand().getName() + ")"
+    if exists(this.getTypeOperand())
+    then result = "__uuidof(" + this.getTypeOperand().getName() + ")"
     else result = "__uuidof(0)"
   }
 

cpp/ql/lib/semmle/code/cpp/exprs/Expr.qll

@@ -26,7 +26,7 @@ class Expr extends StmtParent, @expr {
   Function getEnclosingFunction() { result = exprEnclosingElement(this) }
 
   /** Gets the nearest enclosing set of curly braces around this expression in the source, if any. */
-  BlockStmt getEnclosingBlock() { result = getEnclosingStmt().getEnclosingBlock() }
+  BlockStmt getEnclosingBlock() { result = this.getEnclosingStmt().getEnclosingBlock() }
 
   override Stmt getEnclosingStmt() {
     result = this.getParent().(Expr).getEnclosingStmt()
@@ -219,13 +219,13 @@ class Expr extends StmtParent, @expr {
    * Holds if this expression is a _glvalue_. A _glvalue_ is either an _lvalue_ or an
    * _xvalue_.
    */
-  predicate isGLValueCategory() { isLValueCategory() or isXValueCategory() }
+  predicate isGLValueCategory() { this.isLValueCategory() or this.isXValueCategory() }
 
   /**
    * Holds if this expression is an _rvalue_. An _rvalue_ is either a _prvalue_ or an
    * _xvalue_.
    */
-  predicate isRValueCategory() { isPRValueCategory() or isXValueCategory() }
+  predicate isRValueCategory() { this.isPRValueCategory() or this.isXValueCategory() }
 
   /**
    * Gets a string representation of the value category of the expression.
@@ -240,15 +240,15 @@ class Expr extends StmtParent, @expr {
    * `hasLValueToRvalueConversion()` holds.
    */
   string getValueCategoryString() {
-    isLValueCategory() and
+    this.isLValueCategory() and
     result = "lvalue"
     or
-    isXValueCategory() and
+    this.isXValueCategory() and
     result = "xvalue"
     or
     (
-      isPRValueCategory() and
-      if hasLValueToRValueConversion() then result = "prvalue(load)" else result = "prvalue"
+      this.isPRValueCategory() and
+      if this.hasLValueToRValueConversion() then result = "prvalue(load)" else result = "prvalue"
     )
   }
 
@@ -263,7 +263,7 @@ class Expr extends StmtParent, @expr {
    * such as an expression inside a sizeof.
    */
   predicate isUnevaluated() {
-    exists(Element e | e = getParentWithConversions+() |
+    exists(Element e | e = this.getParentWithConversions+() |
       e instanceof SizeofOperator
       or
       exists(Expr e2 |
@@ -279,7 +279,7 @@ class Expr extends StmtParent, @expr {
       e instanceof AlignofOperator
     )
     or
-    exists(Decltype d | d.getExpr() = getParentWithConversions*())
+    exists(Decltype d | d.getExpr() = this.getParentWithConversions*())
   }
 
   /**
@@ -725,7 +725,7 @@ class PointerDereferenceExpr extends UnaryOperation, @indirect {
    *
    * Gets the expression that is being dereferenced.
    */
-  deprecated Expr getExpr() { result = getOperand() }
+  deprecated Expr getExpr() { result = this.getOperand() }
 
   override string getOperator() { result = "*" }
 
@@ -780,15 +780,15 @@ class NewOrNewArrayExpr extends Expr, @any_new_expr {
    * Gets the alignment argument passed to the allocation function, if any.
    */
   Expr getAlignmentArgument() {
-    hasAlignedAllocation() and
+    this.hasAlignedAllocation() and
     (
       // If we have an allocator call, the alignment is the second argument to
       // that call.
-      result = getAllocatorCall().getArgument(1)
+      result = this.getAllocatorCall().getArgument(1)
       or
       // Otherwise, the alignment winds up as child number 3 of the `new`
       // itself.
-      result = getChild(3)
+      result = this.getChild(3)
     )
   }
 
@@ -916,7 +916,7 @@ class NewArrayExpr extends NewOrNewArrayExpr, @new_array_expr {
    * Gets the element type of the array being allocated.
    */
   Type getAllocatedElementType() {
-    result = getType().getUnderlyingType().(PointerType).getBaseType()
+    result = this.getType().getUnderlyingType().(PointerType).getBaseType()
   }
 
   /**
@@ -946,7 +946,12 @@ class DeleteExpr extends Expr, @delete_expr {
    */
   Type getDeletedObjectType() {
     result =
-      getExpr().getFullyConverted().getType().stripTopLevelSpecifiers().(PointerType).getBaseType()
+      this.getExpr()
+          .getFullyConverted()
+          .getType()
+          .stripTopLevelSpecifiers()
+          .(PointerType)
+          .getBaseType()
   }
 
   /**
@@ -957,7 +962,7 @@ class DeleteExpr extends Expr, @delete_expr {
   /**
    * Gets the destructor to be called to destroy the object, if any.
    */
-  Destructor getDestructor() { result = getDestructorCall().getTarget() }
+  Destructor getDestructor() { result = this.getDestructorCall().getTarget() }
 
   /**
    * Gets the `operator delete` that deallocates storage. Does not hold
@@ -1020,7 +1025,12 @@ class DeleteArrayExpr extends Expr, @delete_array_expr {
    */
   Type getDeletedElementType() {
     result =
-      getExpr().getFullyConverted().getType().stripTopLevelSpecifiers().(PointerType).getBaseType()
+      this.getExpr()
+          .getFullyConverted()
+          .getType()
+          .stripTopLevelSpecifiers()
+          .(PointerType)
+          .getBaseType()
   }
 
   /**
@@ -1034,7 +1044,7 @@ class DeleteArrayExpr extends Expr, @delete_array_expr {
   /**
    * Gets the destructor to be called to destroy each element in the array, if any.
    */
-  Destructor getDestructor() { result = getDestructorCall().getTarget() }
+  Destructor getDestructor() { result = this.getDestructorCall().getTarget() }
 
   /**
    * Gets the `operator delete[]` that deallocates storage.
@@ -1101,7 +1111,7 @@ class StmtExpr extends Expr, @expr_stmt {
    * x = ({ dosomething(); a+b; });
    * ```
    */
-  Expr getResultExpr() { result = getStmtResultExpr(getStmt()) }
+  Expr getResultExpr() { result = getStmtResultExpr(this.getStmt()) }
 }
 
 /** Get the result expression of a statement. (Helper function for StmtExpr.) */
@@ -1230,20 +1240,20 @@ class FoldExpr extends Expr, @foldexpr {
   predicate isRightFold() { fold(underlyingElement(this), _, false) }
 
   /** Holds if this is a unary fold expression. */
-  predicate isUnaryFold() { getNumChild() = 1 }
+  predicate isUnaryFold() { this.getNumChild() = 1 }
 
   /** Holds if this is a binary fold expression. */
-  predicate isBinaryFold() { getNumChild() = 2 }
+  predicate isBinaryFold() { this.getNumChild() = 2 }
 
   /**
    * Gets the child expression containing the unexpanded parameter pack.
    */
   Expr getPackExpr() {
     this.isUnaryFold() and
-    result = getChild(0)
+    result = this.getChild(0)
     or
     this.isBinaryFold() and
-    if this.isRightFold() then result = getChild(0) else result = getChild(1)
+    if this.isRightFold() then result = this.getChild(0) else result = this.getChild(1)
   }
 
   /**
@@ -1251,7 +1261,7 @@ class FoldExpr extends Expr, @foldexpr {
    */
   Expr getInitExpr() {
     this.isBinaryFold() and
-    if this.isRightFold() then result = getChild(1) else result = getChild(0)
+    if this.isRightFold() then result = this.getChild(1) else result = this.getChild(0)
   }
 }
 

cpp/ql/lib/semmle/code/cpp/exprs/Lambda.qll

@@ -24,7 +24,7 @@ class LambdaExpression extends Expr, @lambdaexpr {
   /**
    * Gets an implicitly or explicitly captured value of this lambda expression.
    */
-  LambdaCapture getACapture() { result = getCapture(_) }
+  LambdaCapture getACapture() { result = this.getCapture(_) }
 
   /**
    * Gets the nth implicitly or explicitly captured value of this lambda expression.
@@ -58,13 +58,13 @@ class LambdaExpression extends Expr, @lambdaexpr {
    *   - The return type.
    *   - The statements comprising the lambda body.
    */
-  Operator getLambdaFunction() { result = getType().(Closure).getLambdaFunction() }
+  Operator getLambdaFunction() { result = this.getType().(Closure).getLambdaFunction() }
 
   /**
    * Gets the initializer that initializes the captured variables in the closure, if any.
    * A lambda that does not capture any variables will not have an initializer.
    */
-  ClassAggregateLiteral getInitializer() { result = getChild(0) }
+  ClassAggregateLiteral getInitializer() { result = this.getChild(0) }
 }
 
 /**
@@ -103,7 +103,7 @@ class Closure extends Class {
  * ```
  */
 class LambdaCapture extends Locatable, @lambdacapture {
-  override string toString() { result = getField().getName() }
+  override string toString() { result = this.getField().getName() }
 
   override string getAPrimaryQlClass() { result = "LambdaCapture" }
 

cpp/ql/lib/semmle/code/cpp/exprs/Literal.qll

@@ -60,12 +60,12 @@ class TextLiteral extends Literal {
 
   /** Gets a hex escape sequence that appears in the character or string literal (see [lex.ccon] in the C++ Standard). */
   string getAHexEscapeSequence(int occurrence, int offset) {
-    result = getValueText().regexpFind("(?<!\\\\)\\\\x[0-9a-fA-F]+", occurrence, offset)
+    result = this.getValueText().regexpFind("(?<!\\\\)\\\\x[0-9a-fA-F]+", occurrence, offset)
   }
 
   /** Gets an octal escape sequence that appears in the character or string literal (see [lex.ccon] in the C++ Standard). */
   string getAnOctalEscapeSequence(int occurrence, int offset) {
-    result = getValueText().regexpFind("(?<!\\\\)\\\\[0-7]{1,3}", occurrence, offset)
+    result = this.getValueText().regexpFind("(?<!\\\\)\\\\[0-7]{1,3}", occurrence, offset)
   }
 
   /**
@@ -75,27 +75,27 @@ class TextLiteral extends Literal {
   string getANonStandardEscapeSequence(int occurrence, int offset) {
     // Find all single character escape sequences (ignoring the start of octal escape sequences),
     // together with anything starting like a hex escape sequence but not followed by a hex digit.
-    result = getValueText().regexpFind("\\\\[^x0-7\\s]|\\\\x[^0-9a-fA-F]", occurrence, offset) and
+    result = this.getValueText().regexpFind("\\\\[^x0-7\\s]|\\\\x[^0-9a-fA-F]", occurrence, offset) and
     // From these, exclude all standard escape sequences.
-    not result = getAStandardEscapeSequence(_, _)
+    not result = this.getAStandardEscapeSequence(_, _)
   }
 
   /** Gets a simple escape sequence that appears in the char or string literal (see [lex.ccon] in the C++ Standard). */
   string getASimpleEscapeSequence(int occurrence, int offset) {
-    result = getValueText().regexpFind("\\\\['\"?\\\\abfnrtv]", occurrence, offset)
+    result = this.getValueText().regexpFind("\\\\['\"?\\\\abfnrtv]", occurrence, offset)
   }
 
   /** Gets a standard escape sequence that appears in the char or string literal (see [lex.ccon] in the C++ Standard). */
   string getAStandardEscapeSequence(int occurrence, int offset) {
-    result = getASimpleEscapeSequence(occurrence, offset) or
-    result = getAnOctalEscapeSequence(occurrence, offset) or
-    result = getAHexEscapeSequence(occurrence, offset)
+    result = this.getASimpleEscapeSequence(occurrence, offset) or
+    result = this.getAnOctalEscapeSequence(occurrence, offset) or
+    result = this.getAHexEscapeSequence(occurrence, offset)
   }
 
   /**
    * Gets the length of the string literal (including null) before escape sequences added by the extractor.
    */
-  int getOriginalLength() { result = getValue().length() + 1 }
+  int getOriginalLength() { result = this.getValue().length() + 1 }
 }
 
 /**
@@ -216,7 +216,7 @@ class ClassAggregateLiteral extends AggregateLiteral {
     (
       // If the field has an explicit initializer expression, then the field is
       // initialized.
-      exists(getFieldExpr(field))
+      exists(this.getFieldExpr(field))
       or
       // If the type is not a union, all fields without initializers are value
       // initialized.
@@ -224,7 +224,7 @@ class ClassAggregateLiteral extends AggregateLiteral {
       or
       // If the type is a union, and there are no explicit initializers, then
       // the first declared field is value initialized.
-      not exists(getAChild()) and
+      not exists(this.getAChild()) and
       field.getInitializationOrder() = 0
     )
   }
@@ -239,8 +239,8 @@ class ClassAggregateLiteral extends AggregateLiteral {
    */
   pragma[inline]
   predicate isValueInitialized(Field field) {
-    isInitialized(field) and
-    not exists(getFieldExpr(field))
+    this.isInitialized(field) and
+    not exists(this.getFieldExpr(field))
   }
 }
 
@@ -285,7 +285,7 @@ class ArrayOrVectorAggregateLiteral extends AggregateLiteral {
   bindingset[elementIndex]
   predicate isInitialized(int elementIndex) {
     elementIndex >= 0 and
-    elementIndex < getArraySize()
+    elementIndex < this.getArraySize()
   }
 
   /**
@@ -298,8 +298,8 @@ class ArrayOrVectorAggregateLiteral extends AggregateLiteral {
    */
   bindingset[elementIndex]
   predicate isValueInitialized(int elementIndex) {
-    isInitialized(elementIndex) and
-    not exists(getElementExpr(elementIndex))
+    this.isInitialized(elementIndex) and
+    not exists(this.getElementExpr(elementIndex))
   }
 }
 

cpp/ql/lib/semmle/code/cpp/internal/QualifiedName.qll

@@ -173,7 +173,7 @@ class LocalVariable extends LocalScopeVariable, @localvariable { }
 class VariableDeclarationEntry extends @var_decl {
   string toString() { result = "QualifiedName DeclarationEntry" }
 
-  Variable getDeclaration() { result = getVariable() }
+  Variable getDeclaration() { result = this.getVariable() }
 
   /**
    * Gets the variable which is being declared or defined.

cpp/ql/lib/semmle/code/cpp/ir/dataflow/DefaultTaintTracking.qll

@@ -4,7 +4,7 @@ private import semmle.code.cpp.ir.dataflow.DataFlow
 private import semmle.code.cpp.ir.dataflow.internal.DataFlowUtil
 private import semmle.code.cpp.ir.dataflow.DataFlow3
 private import semmle.code.cpp.ir.IR
-private import semmle.code.cpp.ir.dataflow.internal.DataFlowDispatch as Dispatch
+private import semmle.code.cpp.ir.dataflow.ResolveCall
 private import semmle.code.cpp.controlflow.IRGuards
 private import semmle.code.cpp.models.interfaces.Taint
 private import semmle.code.cpp.models.interfaces.DataFlow
@@ -355,20 +355,6 @@ predicate taintedIncludingGlobalVars(Expr source, Element tainted, string global
  */
 GlobalOrNamespaceVariable globalVarFromId(string id) { id = result.getQualifiedName() }
 
-/**
- * Resolve potential target function(s) for `call`.
- *
- * If `call` is a call through a function pointer (`ExprCall`) or
- * targets a virtual method, simple data flow analysis is performed
- * in order to identify target(s).
- */
-Function resolveCall(Call call) {
-  exists(CallInstruction callInstruction |
-    callInstruction.getAST() = call and
-    result = Dispatch::viableCallable(callInstruction)
-  )
-}
-
 /**
  * Provides definitions for augmenting source/sink pairs with data-flow paths
  * between them. From a `@kind path-problem` query, import this module in the
@@ -479,7 +465,7 @@ module TaintedWithPath {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -550,6 +536,39 @@ module TaintedWithPath {
     )
   }
 
+  /**
+   * Holds if there is flow from `arg` to `out` across a call that can by summarized by the flow
+   * from `par` to `ret` within it, in the graph of data flow path explanations.
+   */
+  query predicate subpaths(PathNode arg, PathNode par, PathNode ret, PathNode out) {
+    DataFlow3::PathGraph::subpaths(arg.(WrapPathNode).inner(), par.(WrapPathNode).inner(),
+      ret.(WrapPathNode).inner(), out.(WrapPathNode).inner())
+    or
+    // To avoid showing trivial-looking steps, we _replace_ the last node instead
+    // of adding an edge out of it.
+    exists(WrapPathNode sinkNode |
+      DataFlow3::PathGraph::subpaths(arg.(WrapPathNode).inner(), par.(WrapPathNode).inner(),
+        ret.(WrapPathNode).inner(), sinkNode.inner()) and
+      out.(FinalPathNode).inner() = adjustedSink(sinkNode.inner().getNode())
+    )
+    or
+    // Same for the first node
+    exists(WrapPathNode sourceNode |
+      DataFlow3::PathGraph::subpaths(sourceNode.inner(), par.(WrapPathNode).inner(),
+        ret.(WrapPathNode).inner(), out.(WrapPathNode).inner()) and
+      sourceNode.inner().getNode() = getNodeForExpr(arg.(InitialPathNode).inner())
+    )
+    or
+    // Finally, handle the case where the path goes directly from a source to a
+    // sink, meaning that they both need to be translated.
+    exists(WrapPathNode sinkNode, WrapPathNode sourceNode |
+      DataFlow3::PathGraph::subpaths(sourceNode.inner(), par.(WrapPathNode).inner(),
+        ret.(WrapPathNode).inner(), sinkNode.inner()) and
+      sourceNode.inner().getNode() = getNodeForExpr(arg.(InitialPathNode).inner()) and
+      out.(FinalPathNode).inner() = adjustedSink(sinkNode.inner().getNode())
+    )
+  }
+
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
     key = "semmle.label" and val = n.toString()

cpp/ql/lib/semmle/code/cpp/ir/dataflow/ResolveCall.qll

@@ -0,0 +1,23 @@
+/**
+ * Provides a predicate for non-contextual virtual dispatch and function
+ * pointer resolution.
+ */
+
+import cpp
+private import semmle.code.cpp.ir.ValueNumbering
+private import internal.DataFlowDispatch
+private import semmle.code.cpp.ir.IR
+
+/**
+ * Resolve potential target function(s) for `call`.
+ *
+ * If `call` is a call through a function pointer (`ExprCall`) or its target is
+ * a virtual member function, simple data flow analysis is performed in order
+ * to identify the possible target(s).
+ */
+Function resolveCall(Call call) {
+  exists(CallInstruction callInstruction |
+    callInstruction.getAST() = call and
+    result = viableCallable(callInstruction)
+  )
+}

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowDispatch.qll

@@ -63,8 +63,10 @@ private module VirtualDispatch {
       |
         // Call argument
         exists(DataFlowCall call, int i |
-          other.(DataFlow::ParameterNode).isParameterOf(call.getStaticCallTarget(), i) and
-          src.(ArgumentNode).argumentOf(call, i)
+          other
+              .(DataFlow::ParameterNode)
+              .isParameterOf(pragma[only_bind_into](call).getStaticCallTarget(), i) and
+          src.(ArgumentNode).argumentOf(call, pragma[only_bind_into](pragma[only_bind_out](i)))
         ) and
         allowOtherFromArg = true and
         allowFromArg = true
@@ -128,6 +130,7 @@ private module VirtualDispatch {
    *
    * Used to fix a join ordering issue in flowsFrom.
    */
+  pragma[noinline]
   private predicate returnNodeWithKindAndEnclosingCallable(
     ReturnNode node, ReturnKind kind, DataFlowCallable callable
   ) {

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl2.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl3.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl4.qll

@@ -110,12 +110,12 @@ abstract class Configuration extends string {
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowTo(Node sink) { hasFlow(_, sink) }
+  predicate hasFlowTo(Node sink) { this.hasFlow(_, sink) }
 
   /**
    * Holds if data may flow from some source to `sink` for this configuration.
    */
-  predicate hasFlowToExpr(DataFlowExpr sink) { hasFlowTo(exprNode(sink)) }
+  predicate hasFlowToExpr(DataFlowExpr sink) { this.hasFlowTo(exprNode(sink)) }
 
   /**
    * Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev`
@@ -244,6 +244,8 @@ private class ParamNodeEx extends NodeEx {
   }
 
   int getPosition() { this.isParameterOf(_, result) }
+
+  predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
 
 private class RetNodeEx extends NodeEx {
@@ -744,8 +746,12 @@ private module Stage1 {
       returnFlowCallableNodeCand(c, kind, config) and
       p.getEnclosingCallable() = c and
       exists(ap) and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = p.getPosition()
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -923,28 +929,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1179,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1392,8 +1400,12 @@ private module Stage2 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -1860,7 +1872,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2080,8 +2093,12 @@ private module Stage3 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2117,7 +2134,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2136,7 +2153,8 @@ private predicate expensiveLen2unfolding(TypedContent tc, Configuration config)
       ) and
     accessPathApproxCostLimits(apLimit, tupleLimit) and
     apLimit < tails and
-    tupleLimit < (tails - 1) * nodes
+    tupleLimit < (tails - 1) * nodes and
+    not tc.forceHighPrecision()
   )
 }
 
@@ -2618,7 +2636,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2838,8 +2857,12 @@ private module Stage4 {
       fwdFlow(ret, any(CcCall ccc), apSome(ap), ap0, config) and
       kind = ret.getKind() and
       p.getPosition() = pos and
-      // we don't expect a parameter to return stored in itself
-      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      // we don't expect a parameter to return stored in itself, unless explicitly allowed
+      (
+        not kind.(ParamUpdateReturnKind).getPosition() = pos
+        or
+        p.allowParameterReturnInSelf()
+      )
     )
   }
 
@@ -2912,6 +2935,8 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   int getParameterPos() { p.isParameterOf(_, result) }
 
+  ParamNodeEx getParamNode() { result = p }
+
   override string toString() { result = p + ": " + ap }
 
   predicate hasLocationInfo(
@@ -2969,12 +2994,15 @@ private AccessPathApprox getATail(AccessPathApprox apa, Configuration config) {
  * expected to be expensive. Holds with `unfold = true` otherwise.
  */
 private predicate evalUnfold(AccessPathApprox apa, boolean unfold, Configuration config) {
-  exists(int aps, int nodes, int apLimit, int tupleLimit |
-    aps = countPotentialAps(apa, config) and
-    nodes = countNodesUsingAccessPath(apa, config) and
-    accessPathCostLimits(apLimit, tupleLimit) and
-    if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
-  )
+  if apa.getHead().forceHighPrecision()
+  then unfold = true
+  else
+    exists(int aps, int nodes, int apLimit, int tupleLimit |
+      aps = countPotentialAps(apa, config) and
+      nodes = countNodesUsingAccessPath(apa, config) and
+      accessPathCostLimits(apLimit, tupleLimit) and
+      if apLimit < aps and tupleLimit < (aps - 1) * nodes then unfold = false else unfold = true
+    )
 }
 
 /**
@@ -3162,7 +3190,7 @@ private class AccessPathCons extends AccessPath, TAccessPathCons {
   }
 
   override string toString() {
-    result = "[" + this.toStringImpl(true) + length().toString() + ")]"
+    result = "[" + this.toStringImpl(true) + this.length().toString() + ")]"
     or
     result = "[" + this.toStringImpl(false)
   }
@@ -3244,7 +3272,7 @@ class PathNode extends TPathNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3301,9 +3329,11 @@ abstract private class PathNodeImpl extends PathNode {
     result = " <" + this.(PathNodeMid).getCallContext().toString() + ">"
   }
 
-  override string toString() { result = this.getNodeEx().toString() + ppAp() }
+  override string toString() { result = this.getNodeEx().toString() + this.ppAp() }
 
-  override string toStringWithContext() { result = this.getNodeEx().toString() + ppAp() + ppCtx() }
+  override string toStringWithContext() {
+    result = this.getNodeEx().toString() + this.ppAp() + this.ppCtx()
+  }
 
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -3320,8 +3350,8 @@ private predicate directReach(PathNode n) {
 /** Holds if `n` can reach a sink or is used in a subpath. */
 private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink or is used in a subpath. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3330,7 +3360,7 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
@@ -3371,11 +3401,11 @@ private class PathNodeMid extends PathNodeImpl, TPathNodeMid {
 
   override PathNodeImpl getASuccessorImpl() {
     // an intermediate step to another intermediate node
-    result = getSuccMid()
+    result = this.getSuccMid()
     or
     // a final step to a sink via zero steps means we merge the last two steps to prevent trivial-looking edges
     exists(PathNodeMid mid, PathNodeSink sink |
-      mid = getSuccMid() and
+      mid = this.getSuccMid() and
       mid.getNodeEx() = sink.getNodeEx() and
       mid.getAp() instanceof AccessPathNil and
       sink.getConfiguration() = unbindConf(mid.getConfiguration()) and
@@ -3452,7 +3482,7 @@ private predicate pathStep(
   exists(TypedContent tc | pathReadStep(mid, node, ap.push(tc), tc, cc)) and
   sc = mid.getSummaryCtx()
   or
-  pathIntoCallable(mid, node, _, cc, sc, _) and ap = mid.getAp()
+  pathIntoCallable(mid, node, _, cc, sc, _, _) and ap = mid.getAp()
   or
   pathOutOfCallable(mid, node, cc) and ap = mid.getAp() and sc instanceof SummaryCtxNone
   or
@@ -3529,14 +3559,16 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa
+  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
+  Configuration config
 ) {
   exists(ArgNode arg |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
     arg.argumentOf(call, i) and
     ap = mid.getAp() and
-    apa = ap.getApprox()
+    apa = ap.getApprox() and
+    config = mid.getConfiguration()
   )
 }
 
@@ -3553,12 +3585,14 @@ private predicate parameterCand(
 pragma[nomagic]
 private predicate pathIntoCallable0(
   PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap
+  AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, i, outercc, call, ap, apa) and
+    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+      pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, any(int j | j <= i and j >= i), apa, mid.getConfiguration())
+    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+      pragma[only_bind_into](config))
   )
 }
 
@@ -3567,12 +3601,13 @@ private predicate pathIntoCallable0(
  * before and after entering the callable are `outercc` and `innercc`,
  * respectively.
  */
+pragma[nomagic]
 private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
-  DataFlowCall call
+  DataFlowCall call, Configuration config
 ) {
   exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap) and
+    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
     p.isParameterOf(callable, i) and
     (
       sc = TSummaryCtxSome(p, ap)
@@ -3602,18 +3637,23 @@ private predicate paramFlowsThrough(
     ap = mid.getAp() and
     apa = ap.getApprox() and
     pos = sc.getParameterPos() and
-    not kind.(ParamUpdateReturnKind).getPosition() = pos
+    // we don't expect a parameter to return stored in itself, unless explicitly allowed
+    (
+      not kind.(ParamUpdateReturnKind).getPosition() = pos
+      or
+      sc.getParamNode().allowParameterReturnInSelf()
+    )
   )
 }
 
 pragma[nomagic]
 private predicate pathThroughCallable0(
   DataFlowCall call, PathNodeMid mid, ReturnKindExt kind, CallContext cc, AccessPath ap,
-  AccessPathApprox apa
+  AccessPathApprox apa, Configuration config
 ) {
   exists(CallContext innercc, SummaryCtx sc |
-    pathIntoCallable(mid, _, cc, innercc, sc, call) and
-    paramFlowsThrough(kind, innercc, sc, ap, apa, unbindConf(mid.getConfiguration()))
+    pathIntoCallable(mid, _, cc, innercc, sc, call, config) and
+    paramFlowsThrough(kind, innercc, sc, ap, apa, config)
   )
 }
 
@@ -3623,9 +3663,9 @@ private predicate pathThroughCallable0(
  */
 pragma[noinline]
 private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext cc, AccessPath ap) {
-  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa |
-    pathThroughCallable0(call, mid, kind, cc, ap, apa) and
-    out = getAnOutNodeFlow(kind, call, apa, unbindConf(mid.getConfiguration()))
+  exists(DataFlowCall call, ReturnKindExt kind, AccessPathApprox apa, Configuration config |
+    pathThroughCallable0(call, mid, kind, cc, ap, apa, config) and
+    out = getAnOutNodeFlow(kind, call, apa, config)
   )
 }
 
@@ -3639,9 +3679,11 @@ private module Subpaths {
     PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
     NodeEx out, AccessPath apout
   ) {
-    pathThroughCallable(arg, out, _, apout) and
-    pathIntoCallable(arg, par, _, innercc, sc, _) and
-    paramFlowsThrough(kind, innercc, sc, apout, _, unbindConf(arg.getConfiguration()))
+    exists(Configuration config |
+      pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+      pathIntoCallable(arg, par, _, innercc, sc, _, config) and
+      paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _, unbindConf(config))
+    )
   }
 
   /**
@@ -3686,8 +3728,8 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
     exists(ParamNodeEx p, NodeEx o, AccessPath apout |
-      arg.getASuccessor() = par and
-      arg.getASuccessor() = out and
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
       subpaths03(arg, p, ret, o, apout) and
       par.getNodeEx() = p and
       out.getNodeEx() = o and
@@ -4028,7 +4070,7 @@ private module FlowExploration {
      * The location spans column `startcolumn` of line `startline` to
      * column `endcolumn` of line `endline` in file `filepath`.
      * For more information, see
-     * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+     * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImplCommon.qll

@@ -786,16 +786,24 @@ private module Cached {
   }
 
   /**
-   * Holds if the call context `call` either improves virtual dispatch in
-   * `callable` or if it allows us to prune unreachable nodes in `callable`.
+   * Holds if the call context `call` improves virtual dispatch in `callable`.
    */
   cached
-  predicate recordDataFlowCallSite(DataFlowCall call, DataFlowCallable callable) {
+  predicate recordDataFlowCallSiteDispatch(DataFlowCall call, DataFlowCallable callable) {
     reducedViableImplInCallContext(_, callable, call)
-    or
+  }
+
+  /**
+   * Holds if the call context `call` allows us to prune unreachable nodes in `callable`.
+   */
+  cached
+  predicate recordDataFlowCallSiteUnreachable(DataFlowCall call, DataFlowCallable callable) {
     exists(Node n | getNodeEnclosingCallable(n) = callable | isUnreachableInCallCached(n, call))
   }
 
+  cached
+  predicate allowParameterReturnInSelfCached(ParamNode p) { allowParameterReturnInSelf(p) }
+
   cached
   newtype TCallContext =
     TAnyCallContext() or
@@ -846,6 +854,15 @@ private module Cached {
     TAccessPathFrontSome(AccessPathFront apf)
 }
 
+/**
+ * Holds if the call context `call` either improves virtual dispatch in
+ * `callable` or if it allows us to prune unreachable nodes in `callable`.
+ */
+predicate recordDataFlowCallSite(DataFlowCall call, DataFlowCallable callable) {
+  recordDataFlowCallSiteDispatch(call, callable) or
+  recordDataFlowCallSiteUnreachable(call, callable)
+}
+
 /**
  * A `Node` at which a cast can occur such that the type should be checked.
  */
@@ -923,7 +940,7 @@ class CallContextSpecificCall extends CallContextCall, TSpecificCall {
   }
 
   override predicate relevantFor(DataFlowCallable callable) {
-    recordDataFlowCallSite(getCall(), callable)
+    recordDataFlowCallSite(this.getCall(), callable)
   }
 
   override predicate matchesCall(DataFlowCall call) { call = this.getCall() }
@@ -1222,6 +1239,13 @@ class TypedContent extends MkTypedContent {
 
   /** Gets a textual representation of this content. */
   string toString() { result = c.toString() }
+
+  /**
+   * Holds if access paths with this `TypedContent` at their head always should
+   * be tracked at high precision. This disables adaptive access path precision
+   * for such access paths.
+   */
+  predicate forceHighPrecision() { forceHighPrecision(c) }
 }
 
 /**
@@ -1236,7 +1260,7 @@ abstract class AccessPathFront extends TAccessPathFront {
 
   TypedContent getHead() { this = TFrontHead(result) }
 
-  predicate isClearedAt(Node n) { clearsContentCached(n, getHead().getContent()) }
+  predicate isClearedAt(Node n) { clearsContentCached(n, this.getHead().getContent()) }
 }
 
 class AccessPathFrontNil extends AccessPathFront, TFrontNil {

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImplConsistency.qll

@@ -175,6 +175,7 @@ module Consistency {
 
   query predicate postWithInFlow(Node n, string msg) {
     isPostUpdateNode(n) and
+    not clearsContent(n, _) and
     simpleLocalFlowStep(_, n) and
     msg = "PostUpdateNode should not be the target of local flow."
   }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowPrivate.qll

@@ -106,11 +106,9 @@ class ReturnNode extends InstructionNode {
   Instruction primary;
 
   ReturnNode() {
-    exists(ReturnValueInstruction ret | instr = ret.getReturnValue() and primary = ret)
+    exists(ReturnValueInstruction ret | instr = ret and primary = ret)
     or
-    exists(ReturnIndirectionInstruction rii |
-      instr = rii.getSideEffectOperand().getAnyDef() and primary = rii
-    )
+    exists(ReturnIndirectionInstruction rii | instr = rii and primary = rii)
   }
 
   /** Gets the kind of this returned value. */
@@ -184,108 +182,16 @@ OutNode getAnOutNode(DataFlowCall call, ReturnKind kind) {
  */
 predicate jumpStep(Node n1, Node n2) { none() }
 
-private predicate fieldStoreStepNoChi(Node node1, FieldContent f, PostUpdateNode node2) {
-  exists(StoreInstruction store, Class c |
-    store = node2.asInstruction() and
-    store.getSourceValueOperand() = node1.asOperand() and
-    getWrittenField(store, f.(FieldContent).getAField(), c) and
-    f.hasOffset(c, _, _)
-  )
-}
-
-private FieldAddressInstruction getFieldInstruction(Instruction instr) {
-  result = instr or
-  result = instr.(CopyValueInstruction).getUnary()
-}
-
-pragma[noinline]
-private predicate getWrittenField(Instruction instr, Field f, Class c) {
-  exists(FieldAddressInstruction fa |
-    fa =
-      getFieldInstruction([
-          instr.(StoreInstruction).getDestinationAddress(),
-          instr.(WriteSideEffectInstruction).getDestinationAddress()
-        ]) and
-    f = fa.getField() and
-    c = f.getDeclaringType()
-  )
-}
-
-private predicate fieldStoreStepChi(Node node1, FieldContent f, PostUpdateNode node2) {
-  exists(ChiPartialOperand operand, ChiInstruction chi |
-    chi.getPartialOperand() = operand and
-    node1.asOperand() = operand and
-    node2.asInstruction() = chi and
-    exists(Class c |
-      c = chi.getResultType() and
-      exists(int startBit, int endBit |
-        chi.getUpdatedInterval(startBit, endBit) and
-        f.hasOffset(c, startBit, endBit)
-      )
-      or
-      getWrittenField(operand.getDef(), f.getAField(), c) and
-      f.hasOffset(c, _, _)
-    )
-  )
-}
-
-private predicate arrayStoreStepChi(Node node1, ArrayContent a, PostUpdateNode node2) {
-  exists(a) and
-  exists(ChiPartialOperand operand, ChiInstruction chi, StoreInstruction store |
-    chi.getPartialOperand() = operand and
-    store = operand.getDef() and
-    node1.asOperand() = operand and
-    // This `ChiInstruction` will always have a non-conflated result because both `ArrayStoreNode`
-    // and `PointerStoreNode` require it in their characteristic predicates.
-    node2.asInstruction() = chi and
-    (
-      // `x[i] = taint()`
-      // This matches the characteristic predicate in `ArrayStoreNode`.
-      store.getDestinationAddress() instanceof PointerAddInstruction
-      or
-      // `*p = taint()`
-      // This matches the characteristic predicate in `PointerStoreNode`.
-      store.getDestinationAddress().(CopyValueInstruction).getUnary() instanceof LoadInstruction
-    )
-  )
-}
-
 /**
  * Holds if data can flow from `node1` to `node2` via an assignment to `f`.
  * Thus, `node2` references an object with a field `f` that contains the
  * value of `node1`.
  */
-predicate storeStep(Node node1, Content f, PostUpdateNode node2) {
-  fieldStoreStepNoChi(node1, f, node2) or
-  fieldStoreStepChi(node1, f, node2) or
-  arrayStoreStepChi(node1, f, node2) or
-  fieldStoreStepAfterArraySuppression(node1, f, node2)
-}
-
-// This predicate pushes the correct `FieldContent` onto the access path when the
-// `suppressArrayRead` predicate has popped off an `ArrayContent`.
-private predicate fieldStoreStepAfterArraySuppression(
-  Node node1, FieldContent f, PostUpdateNode node2
-) {
-  exists(WriteSideEffectInstruction write, ChiInstruction chi, Class c |
-    not chi.isResultConflated() and
-    node1.asInstruction() = chi and
-    node2.asInstruction() = chi and
-    chi.getPartial() = write and
-    getWrittenField(write, f.getAField(), c) and
-    f.hasOffset(c, _, _)
-  )
-}
-
-bindingset[result, i]
-private int unbindInt(int i) { i <= result and i >= result }
-
-pragma[noinline]
-private predicate getLoadedField(LoadInstruction load, Field f, Class c) {
-  exists(FieldAddressInstruction fa |
-    fa = load.getSourceAddress() and
-    f = fa.getField() and
-    c = f.getDeclaringType()
+predicate storeStep(StoreNode node1, FieldContent f, StoreNode node2) {
+  exists(FieldAddressInstruction fai |
+    node1.getInstruction() = fai and
+    node2.getInstruction() = fai.getObjectAddress() and
+    f.getField() = fai.getField()
   )
 }
 
@@ -294,122 +200,14 @@ private predicate getLoadedField(LoadInstruction load, Field f, Class c) {
  * Thus, `node1` references an object with a field `f` whose value ends up in
  * `node2`.
  */
-private predicate fieldReadStep(Node node1, FieldContent f, Node node2) {
-  exists(LoadOperand operand |
-    node2.asOperand() = operand and
-    node1.asInstruction() = operand.getAnyDef() and
-    exists(Class c |
-      c = operand.getAnyDef().getResultType() and
-      exists(int startBit, int endBit |
-        operand.getUsedInterval(unbindInt(startBit), unbindInt(endBit)) and
-        f.hasOffset(c, startBit, endBit)
-      )
-      or
-      getLoadedField(operand.getUse(), f.getAField(), c) and
-      f.hasOffset(c, _, _)
-    )
+predicate readStep(ReadNode node1, FieldContent f, ReadNode node2) {
+  exists(FieldAddressInstruction fai |
+    node1.getInstruction() = fai.getObjectAddress() and
+    node2.getInstruction() = fai and
+    f.getField() = fai.getField()
   )
 }
 
-/**
- * When a store step happens in a function that looks like an array write such as:
- * ```cpp
- * void f(int* pa) {
- *   pa = source();
- * }
- * ```
- * it can be a write to an array, but it can also happen that `f` is called as `f(&a.x)`. If that is
- * the case, the `ArrayContent` that was written by the call to `f` should be popped off the access
- * path, and a `FieldContent` containing `x` should be pushed instead.
- * So this case pops `ArrayContent` off the access path, and the `fieldStoreStepAfterArraySuppression`
- * predicate in `storeStep` ensures that we push the right `FieldContent` onto the access path.
- */
-predicate suppressArrayRead(Node node1, ArrayContent a, Node node2) {
-  exists(a) and
-  exists(WriteSideEffectInstruction write, ChiInstruction chi |
-    node1.asInstruction() = write and
-    node2.asInstruction() = chi and
-    chi.getPartial() = write and
-    getWrittenField(write, _, _)
-  )
-}
-
-private class ArrayToPointerConvertInstruction extends ConvertInstruction {
-  ArrayToPointerConvertInstruction() {
-    this.getUnary().getResultType() instanceof ArrayType and
-    this.getResultType() instanceof PointerType
-  }
-}
-
-private Instruction skipOneCopyValueInstructionRec(CopyValueInstruction copy) {
-  copy.getUnary() = result and not result instanceof CopyValueInstruction
-  or
-  result = skipOneCopyValueInstructionRec(copy.getUnary())
-}
-
-private Instruction skipCopyValueInstructions(Operand op) {
-  not result instanceof CopyValueInstruction and result = op.getDef()
-  or
-  result = skipOneCopyValueInstructionRec(op.getDef())
-}
-
-private predicate arrayReadStep(Node node1, ArrayContent a, Node node2) {
-  exists(a) and
-  // Explicit dereferences such as `*p` or `p[i]` where `p` is a pointer or array.
-  exists(LoadOperand operand, Instruction address |
-    operand.isDefinitionInexact() and
-    node1.asInstruction() = operand.getAnyDef() and
-    operand = node2.asOperand() and
-    address = skipCopyValueInstructions(operand.getAddressOperand()) and
-    (
-      address instanceof LoadInstruction or
-      address instanceof ArrayToPointerConvertInstruction or
-      address instanceof PointerOffsetInstruction
-    )
-  )
-}
-
-/**
- * In cases such as:
- * ```cpp
- * void f(int* pa) {
- *   *pa = source();
- * }
- * ...
- * int x;
- * f(&x);
- * use(x);
- * ```
- * the load on `x` in `use(x)` will exactly overlap with its definition (in this case the definition
- * is a `WriteSideEffect`). This predicate pops the `ArrayContent` (pushed by the store in `f`)
- * from the access path.
- */
-private predicate exactReadStep(Node node1, ArrayContent a, Node node2) {
-  exists(a) and
-  exists(WriteSideEffectInstruction write, ChiInstruction chi |
-    not chi.isResultConflated() and
-    chi.getPartial() = write and
-    node1.asInstruction() = write and
-    node2.asInstruction() = chi and
-    // To distinquish this case from the `arrayReadStep` case we require that the entire variable was
-    // overwritten by the `WriteSideEffectInstruction` (i.e., there is a load that reads the
-    // entire variable).
-    exists(LoadInstruction load | load.getSourceValue() = chi)
-  )
-}
-
-/**
- * Holds if data can flow from `node1` to `node2` via a read of `f`.
- * Thus, `node1` references an object with a field `f` whose value ends up in
- * `node2`.
- */
-predicate readStep(Node node1, Content f, Node node2) {
-  fieldReadStep(node1, f, node2) or
-  arrayReadStep(node1, f, node2) or
-  exactReadStep(node1, f, node2) or
-  suppressArrayRead(node1, f, node2)
-}
-
 /**
  * Holds if values stored inside content `c` are cleared at node `n`.
  */
@@ -441,7 +239,7 @@ private predicate suppressUnusedNode(Node n) { any() }
 // Java QL library compatibility wrappers
 //////////////////////////////////////////////////////////////////////////////
 /** A node that performs a type cast. */
-class CastNode extends InstructionNode {
+class CastNode extends Node {
   CastNode() { none() } // stub implementation
 }
 
@@ -466,6 +264,12 @@ predicate isUnreachableInCall(Node n, DataFlowCall call) { none() } // stub impl
 
 int accessPathLimit() { result = 5 }
 
+/**
+ * Holds if access paths with `c` at their head always should be tracked at high
+ * precision. This disables adaptive access path precision for such access paths.
+ */
+predicate forceHighPrecision(Content c) { none() }
+
 /** The unit type. */
 private newtype TUnit = TMkUnit()
 
@@ -501,3 +305,12 @@ predicate lambdaCall(DataFlowCall call, LambdaCallKind kind, Node receiver) { no
 
 /** Extra data-flow steps needed for lambda flow analysis. */
 predicate additionalLambdaFlowStep(Node nodeFrom, Node nodeTo, boolean preservesValue) { none() }
+
+/**
+ * Holds if flow is allowed to pass from parameter `p` and back to itself as a
+ * side-effect, resulting in a summary from `p` to itself.
+ *
+ * One example would be to allow flow like `p.foo = p.bar;`, which is disallowed
+ * by default as a heuristic.
+ */
+predicate allowParameterReturnInSelf(ParameterNode p) { none() }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll

@@ -10,6 +10,8 @@ private import semmle.code.cpp.ir.ValueNumbering
 private import semmle.code.cpp.ir.IR
 private import semmle.code.cpp.controlflow.IRGuards
 private import semmle.code.cpp.models.interfaces.DataFlow
+private import DataFlowPrivate
+private import Ssa as Ssa
 
 cached
 private module Cached {
@@ -17,12 +19,30 @@ private module Cached {
   newtype TIRDataFlowNode =
     TInstructionNode(Instruction i) or
     TOperandNode(Operand op) or
-    TVariableNode(Variable var)
+    TVariableNode(Variable var) or
+    TStoreNodeInstr(Instruction i) { Ssa::explicitWrite(_, _, i) } or
+    TStoreNodeOperand(ArgumentOperand op) { Ssa::explicitWrite(_, _, op.getDef()) } or
+    TReadNode(Instruction i) { needsPostReadNode(i) } or
+    TSsaPhiNode(Ssa::PhiNode phi)
 
   cached
   predicate localFlowStepCached(Node nodeFrom, Node nodeTo) {
     simpleLocalFlowStep(nodeFrom, nodeTo)
   }
+
+  private predicate needsPostReadNode(Instruction iFrom) {
+    // If the instruction generates an address that flows to a load.
+    Ssa::addressFlowTC(iFrom, Ssa::getSourceAddress(_)) and
+    (
+      // And it is either a field address
+      iFrom instanceof FieldAddressInstruction
+      or
+      // Or it is instruction that either uses or is used for an address that needs a post read node.
+      exists(Instruction mid | needsPostReadNode(mid) |
+        Ssa::addressFlow(mid, iFrom) or Ssa::addressFlow(iFrom, mid)
+      )
+    )
+  }
 }
 
 private import Cached
@@ -110,7 +130,7 @@ class Node extends TIRDataFlowNode {
   /**
    * Gets an upper bound on the type of this node.
    */
-  IRType getTypeBound() { result = getType() }
+  IRType getTypeBound() { result = this.getType() }
 
   /** Gets the location of this element. */
   Location getLocation() { none() } // overridden by subclasses
@@ -120,7 +140,7 @@ class Node extends TIRDataFlowNode {
    * The location spans column `startcolumn` of line `startline` to
    * column `endcolumn` of line `endline` in file `filepath`.
    * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
   predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
@@ -180,6 +200,186 @@ class OperandNode extends Node, TOperandNode {
   override string toString() { result = this.getOperand().toString() }
 }
 
+/**
+ * INTERNAL: do not use.
+ *
+ * A `StoreNode` is a node that has been (or is about to be) the
+ * source or target of a `storeStep`.
+ */
+abstract class StoreNode extends Node {
+  /** Gets the underlying instruction, if any. */
+  Instruction getInstruction() { none() }
+
+  /** Gets the underlying operand, if any. */
+  Operand getOperand() { none() }
+
+  /** Holds if this node should receive flow from `addr`. */
+  abstract predicate flowInto(Instruction addr);
+
+  override Declaration getEnclosingCallable() { result = this.getFunction() }
+
+  /** Holds if this `StoreNode` is the root of the address computation used by a store operation. */
+  predicate isTerminal() {
+    not exists(this.getAPredecessor()) and
+    not storeStep(this, _, _)
+  }
+
+  /** Gets the store operation that uses the address computed by this `StoreNode`. */
+  abstract Instruction getStoreInstruction();
+
+  /** Holds if the store operation associated with this `StoreNode` overwrites the entire variable. */
+  final predicate isCertain() { Ssa::explicitWrite(true, this.getStoreInstruction(), _) }
+
+  /**
+   * Gets the `StoreNode` that computes the address used by this `StoreNode`.
+   * The boolean `readEffect` is `true` if the predecessor is accessed through the
+   * address of a `ReadSideEffectInstruction`.
+   */
+  abstract StoreNode getAPredecessor();
+
+  /** The inverse of `StoreNode.getAPredecessor`. */
+  final StoreNode getASuccessor() { result.getAPredecessor() = this }
+}
+
+private class StoreNodeInstr extends StoreNode, TStoreNodeInstr {
+  Instruction instr;
+
+  StoreNodeInstr() { this = TStoreNodeInstr(instr) }
+
+  override predicate flowInto(Instruction addr) { this.getInstruction() = addr }
+
+  override Instruction getInstruction() { result = instr }
+
+  override Function getFunction() { result = this.getInstruction().getEnclosingFunction() }
+
+  override IRType getType() { result = this.getInstruction().getResultIRType() }
+
+  override Location getLocation() { result = this.getInstruction().getLocation() }
+
+  override string toString() {
+    result = instructionNode(this.getInstruction()).toString() + " [store]"
+  }
+
+  override Instruction getStoreInstruction() {
+    Ssa::explicitWrite(_, result, this.getInstruction())
+  }
+
+  override StoreNode getAPredecessor() {
+    Ssa::addressFlow(result.getInstruction(), this.getInstruction())
+  }
+}
+
+private class StoreNodeOperand extends StoreNode, TStoreNodeOperand {
+  ArgumentOperand operand;
+
+  StoreNodeOperand() { this = TStoreNodeOperand(operand) }
+
+  override predicate flowInto(Instruction addr) { this.getOperand().getDef() = addr }
+
+  override Operand getOperand() { result = operand }
+
+  override Function getFunction() { result = operand.getDef().getEnclosingFunction() }
+
+  override IRType getType() { result = operand.getIRType() }
+
+  override Location getLocation() { result = operand.getLocation() }
+
+  override string toString() { result = operandNode(this.getOperand()).toString() + " [store]" }
+
+  override WriteSideEffectInstruction getStoreInstruction() {
+    Ssa::explicitWrite(_, result, operand.getDef())
+  }
+
+  override StoreNode getAPredecessor() { operand.getDef() = result.getInstruction() }
+}
+
+/**
+ * INTERNAL: do not use.
+ *
+ * A `ReadNode` is a node that has been (or is about to be) the
+ * source or target of a `readStep`.
+ */
+class ReadNode extends Node, TReadNode {
+  Instruction i;
+
+  ReadNode() { this = TReadNode(i) }
+
+  /** Gets the underlying instruction. */
+  Instruction getInstruction() { result = i }
+
+  override Declaration getEnclosingCallable() { result = this.getFunction() }
+
+  override Function getFunction() { result = this.getInstruction().getEnclosingFunction() }
+
+  override IRType getType() { result = this.getInstruction().getResultIRType() }
+
+  override Location getLocation() { result = this.getInstruction().getLocation() }
+
+  override string toString() {
+    result = instructionNode(this.getInstruction()).toString() + " [read]"
+  }
+
+  /** Gets a load instruction that uses the address computed by this read node. */
+  final Instruction getALoadInstruction() {
+    Ssa::addressFlowTC(this.getInstruction(), Ssa::getSourceAddress(result))
+  }
+
+  /**
+   * Gets a read node with an underlying instruction that is used by this
+   * underlying instruction to compute an address of a load instruction.
+   */
+  final ReadNode getAPredecessor() {
+    Ssa::addressFlow(result.getInstruction(), this.getInstruction())
+  }
+
+  /** The inverse of `ReadNode.getAPredecessor`. */
+  final ReadNode getASuccessor() { result.getAPredecessor() = this }
+
+  /** Holds if this read node computes a value that will not be used for any future read nodes. */
+  final predicate isTerminal() {
+    not exists(this.getASuccessor()) and
+    not readStep(this, _, _)
+  }
+
+  /** Holds if this read node computes a value that has not yet been used for any read operations. */
+  final predicate isInitial() {
+    not exists(this.getAPredecessor()) and
+    not readStep(_, _, this)
+  }
+}
+
+/**
+ * INTERNAL: do not use.
+ *
+ * A phi node produced by the shared SSA library, viewed as a node in a data flow graph.
+ */
+class SsaPhiNode extends Node, TSsaPhiNode {
+  Ssa::PhiNode phi;
+
+  SsaPhiNode() { this = TSsaPhiNode(phi) }
+
+  /* Get the phi node associated with this node. */
+  Ssa::PhiNode getPhiNode() { result = phi }
+
+  override Declaration getEnclosingCallable() { result = this.getFunction() }
+
+  override Function getFunction() { result = phi.getBasicBlock().getEnclosingFunction() }
+
+  override IRType getType() { result instanceof IRVoidType }
+
+  override Location getLocation() { result = phi.getBasicBlock().getLocation() }
+
+  /** Holds if this phi node has input from the `rnk`'th write operation in block `block`. */
+  cached
+  final predicate hasInputAtRankInBlock(IRBlock block, int rnk) {
+    exists(Ssa::Definition input |
+      Ssa::phiHasInputFromBlock(phi, input, _) and input.definesAt(_, block, rnk)
+    )
+  }
+
+  override string toString() { result = "Phi" }
+}
+
 /**
  * An expression, viewed as a node in a data flow graph.
  */
@@ -313,15 +513,14 @@ deprecated class UninitializedNode extends Node {
  * Nodes corresponding to AST elements, for example `ExprNode`, usually refer
  * to the value before the update with the exception of `ClassInstanceExpr`,
  * which represents the value after the constructor has run.
- *
- * This class exists to match the interface used by Java. There are currently no non-abstract
- * classes that extend it. When we implement field flow, we can revisit this.
  */
-abstract class PostUpdateNode extends InstructionNode {
+abstract class PostUpdateNode extends Node {
   /**
    * Gets the node before the state update.
    */
   abstract Node getPreUpdateNode();
+
+  override string toString() { result = this.getPreUpdateNode() + " [post update]" }
 }
 
 /**
@@ -332,7 +531,7 @@ abstract class PostUpdateNode extends InstructionNode {
  * value, but does not necessarily replace it entirely. For example:
  * ```
  * x.y = 1; // a partial definition of the object `x`.
- * x.y.z = 1; // a partial definition of the object `x.y`.
+ * x.y.z = 1; // a partial definition of the object `x.y` and `x`.
  * x.setY(1); // a partial definition of the object `x`.
  * setY(&x); // a partial definition of the object `x`.
  * ```
@@ -341,135 +540,34 @@ abstract private class PartialDefinitionNode extends PostUpdateNode {
   abstract Expr getDefinedExpr();
 }
 
-private class ExplicitFieldStoreQualifierNode extends PartialDefinitionNode {
-  override ChiInstruction instr;
-  StoreInstruction store;
-
-  ExplicitFieldStoreQualifierNode() {
-    not instr.isResultConflated() and
-    instr.getPartial() = store and
-    (
-      instr.getUpdatedInterval(_, _) or
-      store.getDestinationAddress() instanceof FieldAddressInstruction
-    )
+private class FieldPartialDefinitionNode extends PartialDefinitionNode, StoreNodeInstr {
+  FieldPartialDefinitionNode() {
+    this.getInstruction() = any(FieldAddressInstruction fai).getObjectAddress()
   }
 
-  // By using an operand as the result of this predicate we avoid the dataflow inconsistency errors
-  // caused by having multiple nodes sharing the same pre update node. This inconsistency error can cause
-  // a tuple explosion in the big step dataflow relation since it can make many nodes be the entry node
-  // into a big step.
-  override Node getPreUpdateNode() { result.asOperand() = instr.getTotalOperand() }
+  override Node getPreUpdateNode() { result.asInstruction() = this.getInstruction() }
+
+  override Expr getDefinedExpr() { result = this.getInstruction().getUnconvertedResultExpression() }
+
+  override string toString() { result = PartialDefinitionNode.super.toString() }
+}
+
+private class NonPartialDefinitionPostUpdate extends PostUpdateNode, StoreNodeInstr {
+  NonPartialDefinitionPostUpdate() { not this instanceof PartialDefinitionNode }
+
+  override Node getPreUpdateNode() { result.asInstruction() = this.getInstruction() }
+
+  override string toString() { result = PostUpdateNode.super.toString() }
+}
+
+private class ArgumentPostUpdateNode extends PartialDefinitionNode, StoreNodeOperand {
+  override ArgumentNode getPreUpdateNode() { result.asOperand() = operand }
 
   override Expr getDefinedExpr() {
-    result =
-      store
-          .getDestinationAddress()
-          .(FieldAddressInstruction)
-          .getObjectAddress()
-          .getUnconvertedResultExpression()
-  }
-}
-
-/**
- * Not every store instruction generates a chi instruction that we can attach a PostUpdateNode to.
- * For instance, an update to a field of a struct containing only one field. Even if the store does
- * have a chi instruction, a subsequent use of the result of the store may be linked directly to the
- * result of the store as an inexact definition if the store totally overlaps the use. For these
- * cases we attach the PostUpdateNode to the store instruction. There's no obvious pre update node
- * for this case (as the entire memory is updated), so `getPreUpdateNode` is implemented as
- * `none()`.
- */
-private class ExplicitSingleFieldStoreQualifierNode extends PartialDefinitionNode {
-  override StoreInstruction instr;
-
-  ExplicitSingleFieldStoreQualifierNode() {
-    (
-      instr.getAUse().isDefinitionInexact()
-      or
-      not exists(ChiInstruction chi | chi.getPartial() = instr)
-    ) and
-    // Without this condition any store would create a `PostUpdateNode`.
-    instr.getDestinationAddress() instanceof FieldAddressInstruction
+    result = this.getOperand().getDef().getUnconvertedResultExpression()
   }
 
-  override Node getPreUpdateNode() { none() }
-
-  override Expr getDefinedExpr() {
-    result =
-      instr
-          .getDestinationAddress()
-          .(FieldAddressInstruction)
-          .getObjectAddress()
-          .getUnconvertedResultExpression()
-  }
-}
-
-private FieldAddressInstruction getFieldInstruction(Instruction instr) {
-  result = instr or
-  result = instr.(CopyValueInstruction).getUnary()
-}
-
-/**
- * The target of a `fieldStoreStepAfterArraySuppression` store step, which is used to convert
- * an `ArrayContent` to a `FieldContent` when the `WriteSideEffect` instruction stores
- * into a field. See the QLDoc for `suppressArrayRead` for an example of where such a conversion
- * is inserted.
- */
-private class WriteSideEffectFieldStoreQualifierNode extends PartialDefinitionNode {
-  override ChiInstruction instr;
-  WriteSideEffectInstruction write;
-  FieldAddressInstruction field;
-
-  WriteSideEffectFieldStoreQualifierNode() {
-    not instr.isResultConflated() and
-    instr.getPartial() = write and
-    field = getFieldInstruction(write.getDestinationAddress())
-  }
-
-  override Node getPreUpdateNode() { result.asOperand() = instr.getTotalOperand() }
-
-  override Expr getDefinedExpr() {
-    result = field.getObjectAddress().getUnconvertedResultExpression()
-  }
-}
-
-/**
- * The `PostUpdateNode` that is the target of a `arrayStoreStepChi` store step. The overriden
- * `ChiInstruction` corresponds to the instruction represented by `node2` in `arrayStoreStepChi`.
- */
-private class ArrayStoreNode extends PartialDefinitionNode {
-  override ChiInstruction instr;
-  PointerAddInstruction add;
-
-  ArrayStoreNode() {
-    not instr.isResultConflated() and
-    exists(StoreInstruction store |
-      instr.getPartial() = store and
-      add = store.getDestinationAddress()
-    )
-  }
-
-  override Node getPreUpdateNode() { result.asOperand() = instr.getTotalOperand() }
-
-  override Expr getDefinedExpr() { result = add.getLeft().getUnconvertedResultExpression() }
-}
-
-/**
- * The `PostUpdateNode` that is the target of a `arrayStoreStepChi` store step. The overriden
- * `ChiInstruction` corresponds to the instruction represented by `node2` in `arrayStoreStepChi`.
- */
-private class PointerStoreNode extends PostUpdateNode {
-  override ChiInstruction instr;
-
-  PointerStoreNode() {
-    not instr.isResultConflated() and
-    exists(StoreInstruction store |
-      instr.getPartial() = store and
-      store.getDestinationAddress().(CopyValueInstruction).getUnary() instanceof LoadInstruction
-    )
-  }
-
-  override Node getPreUpdateNode() { result.asOperand() = instr.getTotalOperand() }
+  override string toString() { result = PartialDefinitionNode.super.toString() }
 }
 
 /**
@@ -548,6 +646,11 @@ class VariableNode extends Node, TVariableNode {
  */
 InstructionNode instructionNode(Instruction instr) { result.getInstruction() = instr }
 
+/**
+ * Gets the node corresponding to `operand`.
+ */
+OperandNode operandNode(Operand operand) { result.getOperand() = operand }
+
 /**
  * DEPRECATED: use `definitionByReferenceNodeFromArgument` instead.
  *
@@ -614,61 +717,182 @@ predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo) {
   or
   // Instruction -> Operand flow
   simpleOperandLocalFlowStep(nodeFrom.asInstruction(), nodeTo.asOperand())
-}
-
-pragma[noinline]
-private predicate getFieldSizeOfClass(Class c, Type type, int size) {
-  exists(Field f |
-    f.getDeclaringType() = c and
-    f.getUnderlyingType() = type and
-    type.getSize() = size
+  or
+  // Flow into, through, and out of store nodes
+  StoreNodeFlow::flowInto(nodeFrom, nodeTo)
+  or
+  StoreNodeFlow::flowThrough(nodeFrom, nodeTo)
+  or
+  StoreNodeFlow::flowOutOf(nodeFrom, nodeTo)
+  or
+  // Flow into, through, and out of read nodes
+  ReadNodeFlow::flowInto(nodeFrom, nodeTo)
+  or
+  ReadNodeFlow::flowThrough(nodeFrom, nodeTo)
+  or
+  ReadNodeFlow::flowOutOf(nodeFrom, nodeTo)
+  or
+  // Adjacent-def-use and adjacent-use-use flow
+  adjacentDefUseFlow(nodeFrom, nodeTo)
+  or
+  // When we want to transfer flow out of a `StoreNode` we perform two steps:
+  // 1. Find the next use of the address being stored to
+  // 2. Find the `LoadInstruction` that loads the address
+  // When the address being stored into doesn't have a `LoadInstruction` associated with it because it's
+  // passed into a `CallInstruction` we transfer flow to the `ReadSideEffect`, which will then flow into
+  // the callee. We then pickup the flow from the `InitializeIndirectionInstruction` and use the shared
+  // SSA library to determine where the next use of the address that received the flow is.
+  exists(Node init |
+    nodeFrom.asInstruction().(InitializeIndirectionInstruction).getIRVariable() =
+      init.asInstruction().(InitializeParameterInstruction).getIRVariable() and
+    // No need for the flow if the next use is the instruction that returns the flow out of the callee.
+    not nodeTo.asInstruction() instanceof ReturnIndirectionInstruction and
+    Ssa::ssaFlow(init, nodeTo)
   )
 }
 
-private predicate isSingleFieldClass(Type type, Operand op) {
-  exists(int size, Class c |
-    c = op.getType().getUnderlyingType() and
-    c.getSize() = size and
-    getFieldSizeOfClass(c, type, size)
+private predicate adjacentDefUseFlow(Node nodeFrom, Node nodeTo) {
+  // Flow that isn't already covered by field flow out of store/read nodes.
+  not nodeFrom.asInstruction() = any(StoreNode pun).getStoreInstruction() and
+  not nodeFrom.asInstruction() = any(ReadNode pun).getALoadInstruction() and
+  (
+    //Def-use flow
+    Ssa::ssaFlow(nodeFrom, nodeTo)
+    or
+    exists(Instruction loadAddress | loadAddress = Ssa::getSourceAddressFromNode(nodeFrom) |
+      // Use-use flow through reads
+      exists(Node address |
+        Ssa::addressFlowTC(address.asInstruction(), loadAddress) and
+        Ssa::ssaFlow(address, nodeTo)
+      )
+      or
+      // Use-use flow through stores.
+      exists(Node store |
+        Ssa::explicitWrite(_, store.asInstruction(), loadAddress) and
+        Ssa::ssaFlow(store, nodeTo)
+      )
+    )
   )
 }
 
+private module ReadNodeFlow {
+  /** Holds if the read node `nodeTo` should receive flow from `nodeFrom`. */
+  predicate flowInto(Node nodeFrom, ReadNode nodeTo) {
+    nodeTo.isInitial() and
+    (
+      // If we entered through an address operand.
+      nodeFrom.asOperand().getDef() = nodeTo.getInstruction()
+      or
+      // If we entered flow through a memory-producing instruction.
+      // This can happen if we have flow to an `InitializeParameterIndirection` through
+      // a `ReadSideEffectInstruction`.
+      exists(Instruction load, Instruction def |
+        def = nodeFrom.asInstruction() and
+        def = Ssa::getSourceValueOperand(load).getAnyDef() and
+        not def = any(StoreNode store).getStoreInstruction() and
+        pragma[only_bind_into](nodeTo).getALoadInstruction() = load
+      )
+    )
+  }
+
+  /** Holds if the read node `nodeTo` should receive flow from the read node `nodeFrom`. */
+  predicate flowThrough(ReadNode nodeFrom, ReadNode nodeTo) {
+    not readStep(nodeFrom, _, _) and
+    nodeFrom.getASuccessor() = nodeTo
+  }
+
+  /**
+   * Holds if flow should leave the read node `nFrom` and enter the node `nodeTo`.
+   * This happens either because there is use-use flow from one of the variables used in
+   * the read operation, or because we have traversed all the field dereferences in the
+   * read operation.
+   */
+  predicate flowOutOf(ReadNode nFrom, Node nodeTo) {
+    // Use-use flow to another use of the same variable instruction
+    Ssa::ssaFlow(nFrom, nodeTo)
+    or
+    not exists(nFrom.getAPredecessor()) and
+    exists(Node store |
+      Ssa::explicitWrite(_, store.asInstruction(), nFrom.getInstruction()) and
+      Ssa::ssaFlow(store, nodeTo)
+    )
+    or
+    // Flow out of read nodes and into memory instructions if we cannot move any further through
+    // read nodes.
+    nFrom.isTerminal() and
+    (
+      exists(Instruction load |
+        load = nodeTo.asInstruction() and
+        Ssa::getSourceAddress(load) = nFrom.getInstruction()
+      )
+      or
+      exists(CallInstruction call, int i |
+        call.getArgument(i) = nodeTo.asInstruction() and
+        call.getArgument(i) = nFrom.getInstruction()
+      )
+    )
+  }
+}
+
+private module StoreNodeFlow {
+  /** Holds if the store node `nodeTo` should receive flow from `nodeFrom`. */
+  predicate flowInto(Node nodeFrom, StoreNode nodeTo) {
+    nodeTo.flowInto(Ssa::getDestinationAddress(nodeFrom.asInstruction()))
+  }
+
+  /** Holds if the store node `nodeTo` should receive flow from `nodeFom`. */
+  predicate flowThrough(StoreNode nFrom, StoreNode nodeTo) {
+    // Flow through a post update node that doesn't need a store step.
+    not storeStep(nFrom, _, _) and
+    nodeTo.getASuccessor() = nFrom
+  }
+
+  /**
+   * Holds if flow should leave the store node `nodeFrom` and enter the node `nodeTo`.
+   * This happens because we have traversed an entire chain of field dereferences
+   * after a store operation.
+   */
+  predicate flowOutOf(StoreNode nFrom, Node nodeTo) {
+    nFrom.isTerminal() and
+    Ssa::ssaFlow(nFrom, nodeTo)
+  }
+}
+
 private predicate simpleOperandLocalFlowStep(Instruction iFrom, Operand opTo) {
   // Propagate flow from an instruction to its exact uses.
+  // We do this for all instruction/operand pairs, except when the operand is the
+  // side effect operand of a ReturnIndirectionInstruction, or the load operand of a LoadInstruction.
+  // This is because we get these flows through the shared SSA library already, and including this
+  // flow here will create multiple dataflow paths which creates a blowup in stage 3 of dataflow.
+  (
+    not any(ReturnIndirectionInstruction ret).getSideEffectOperand() = opTo and
+    not any(LoadInstruction load).getSourceValueOperand() = opTo and
+    not any(ReturnValueInstruction ret).getReturnValueOperand() = opTo
+  ) and
   opTo.getDef() = iFrom
-  or
-  opTo = any(ReadSideEffectInstruction read).getSideEffectOperand() and
-  not iFrom.isResultConflated() and
-  iFrom = opTo.getAnyDef()
-  or
-  // Loading a single `int` from an `int *` parameter is not an exact load since
-  // the parameter may point to an entire array rather than a single `int`. The
-  // following rule ensures that any flow going into the
-  // `InitializeIndirectionInstruction`, even if it's for a different array
-  // element, will propagate to a load of the first element.
-  //
-  // Since we're linking `InitializeIndirectionInstruction` and
-  // `LoadInstruction` together directly, this rule will break if there's any
-  // reassignment of the parameter indirection, including a conditional one that
-  // leads to a phi node.
-  exists(InitializeIndirectionInstruction init |
-    iFrom = init and
-    opTo.(LoadOperand).getAnyDef() = init and
-    // Check that the types match. Otherwise we can get flow from an object to
-    // its fields, which leads to field conflation when there's flow from other
-    // fields to the object elsewhere.
-    init.getParameter().getType().getUnspecifiedType().(DerivedType).getBaseType() =
-      opTo.getType().getUnspecifiedType()
-  )
-  or
-  // Flow from stores to structs with a single field to a load of that field.
-  exists(LoadInstruction load |
-    load.getSourceValueOperand() = opTo and
-    opTo.getAnyDef() = iFrom and
-    isSingleFieldClass(pragma[only_bind_out](pragma[only_bind_out](iFrom).getResultType()), opTo)
+}
+
+pragma[noinline]
+private predicate getAddressType(LoadInstruction load, Type t) {
+  exists(Instruction address |
+    address = load.getSourceAddress() and
+    t = address.getResultType()
   )
 }
 
+/**
+ * Like the AST dataflow library, we want to conflate the address and value of a reference. This class
+ * represents the `LoadInstruction` that is generated from a reference dereference.
+ */
+private class ReferenceDereferenceInstruction extends LoadInstruction {
+  ReferenceDereferenceInstruction() {
+    exists(ReferenceType ref |
+      getAddressType(this, ref) and
+      this.getResultType() = ref.getBaseType()
+    )
+  }
+}
+
 private predicate simpleInstructionLocalFlowStep(Operand opFrom, Instruction iTo) {
   iTo.(CopyInstruction).getSourceValueOperand() = opFrom
   or
@@ -681,40 +905,8 @@ private predicate simpleInstructionLocalFlowStep(Operand opFrom, Instruction iTo
   or
   iTo.(InheritanceConversionInstruction).getUnaryOperand() = opFrom
   or
-  // A chi instruction represents a point where a new value (the _partial_
-  // operand) may overwrite an old value (the _total_ operand), but the alias
-  // analysis couldn't determine that it surely will overwrite every bit of it or
-  // that it surely will overwrite no bit of it.
-  //
-  // By allowing flow through the total operand, we ensure that flow is not lost
-  // due to shortcomings of the alias analysis. We may get false flow in cases
-  // where the data is indeed overwritten.
-  //
-  // Flow through the partial operand belongs in the taint-tracking libraries
-  // for now.
-  iTo.getAnOperand().(ChiTotalOperand) = opFrom
-  or
-  // Add flow from write side-effects to non-conflated chi instructions through their
-  // partial operands. From there, a `readStep` will find subsequent reads of that field.
-  // Consider the following example:
-  // ```
-  // void setX(Point* p, int new_x) {
-  //   p->x = new_x;
-  // }
-  // ...
-  // setX(&p, taint());
-  // ```
-  // Here, a `WriteSideEffectInstruction` will provide a new definition for `p->x` after the call to
-  // `setX`, which will be melded into `p` through a chi instruction.
-  exists(ChiInstruction chi | chi = iTo |
-    opFrom.getAnyDef() instanceof WriteSideEffectInstruction and
-    chi.getPartialOperand() = opFrom and
-    not chi.isResultConflated() and
-    // In a call such as `set_value(&x->val);` we don't want the memory representing `x` to receive
-    // dataflow by a simple step. Instead, this is handled by field flow. If we add a simple step here
-    // we can get field-to-object flow.
-    not chi.isPartialUpdate()
-  )
+  // Conflate references and values like in AST dataflow.
+  iTo.(ReferenceDereferenceInstruction).getSourceAddressOperand() = opFrom
   or
   // Flow through modeled functions
   modelFlow(opFrom, iTo)
@@ -788,25 +980,10 @@ predicate localInstructionFlow(Instruction e1, Instruction e2) {
  */
 predicate localExprFlow(Expr e1, Expr e2) { localFlow(exprNode(e1), exprNode(e2)) }
 
-/**
- * Gets a field corresponding to the bit range `[startBit..endBit)` of class `c`, if any.
- */
-private Field getAField(Class c, int startBit, int endBit) {
-  result.getDeclaringType() = c and
-  startBit = 8 * result.getByteOffset() and
-  endBit = 8 * result.getType().getSize() + startBit
-  or
-  exists(Field f, Class cInner |
-    f = c.getAField() and
-    cInner = f.getUnderlyingType() and
-    result = getAField(cInner, startBit - 8 * f.getByteOffset(), endBit - 8 * f.getByteOffset())
-  )
-}
-
 private newtype TContent =
-  TFieldContent(Class c, int startBit, int endBit) { exists(getAField(c, startBit, endBit)) } or
-  TCollectionContent() or
-  TArrayContent()
+  TFieldContent(Field f) or
+  TCollectionContent() or // Not used in C/C++
+  TArrayContent() // Not used in C/C++.
 
 /**
  * A description of the way data may be stored inside an object. Examples
@@ -824,18 +1001,13 @@ class Content extends TContent {
 
 /** A reference through an instance field. */
 class FieldContent extends Content, TFieldContent {
-  Class c;
-  int startBit;
-  int endBit;
+  Field f;
 
-  FieldContent() { this = TFieldContent(c, startBit, endBit) }
+  FieldContent() { this = TFieldContent(f) }
 
-  // Ensure that there's just 1 result for `toString`.
-  override string toString() { result = min(Field f | f = getAField() | f.toString()) }
+  override string toString() { result = f.toString() }
 
-  predicate hasOffset(Class cl, int start, int end) { cl = c and start = startBit and end = endBit }
-
-  Field getAField() { result = getAField(c, startBit, endBit) }
+  Field getField() { result = f }
 }
 
 /** A reference through an array. */

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/ModelUtil.qll

@@ -38,5 +38,8 @@ Instruction callOutput(CallInstruction call, FunctionOutput output) {
     effect.getPrimaryInstruction() = call and
     output.isParameterDerefOrQualifierObject(effect.getIndex())
   )
-  // TODO: return value dereference
+  or
+  // TODO: modify this when we get return value dereferences
+  result = call and
+  output.isReturnValueDeref()
 }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/Ssa.qll

@@ -0,0 +1,489 @@
+import SsaImplCommon
+import SsaImplSpecific
+private import cpp as Cpp
+private import semmle.code.cpp.ir.IR
+private import DataFlowUtil
+private import DataFlowPrivate
+private import semmle.code.cpp.models.interfaces.Allocation as Alloc
+private import semmle.code.cpp.models.interfaces.DataFlow as DataFlow
+
+cached
+private newtype TDefOrUse =
+  TExplicitDef(Instruction store) { explicitWrite(_, store, _) } or
+  TInitializeParam(Instruction instr) {
+    instr instanceof InitializeParameterInstruction
+    or
+    instr instanceof InitializeIndirectionInstruction
+  } or
+  TExplicitUse(Operand op) { isExplicitUse(op) } or
+  TReturnParamIndirection(Operand op) { returnParameterIndirection(op, _) }
+
+pragma[nomagic]
+private int getRank(DefOrUse defOrUse, IRBlock block) {
+  defOrUse =
+    rank[result](int i, DefOrUse cand |
+      block.getInstruction(i) = toInstruction(cand)
+    |
+      cand order by i
+    )
+}
+
+private class DefOrUse extends TDefOrUse {
+  /** Gets the instruction associated with this definition, if any. */
+  Instruction asDef() { none() }
+
+  /** Gets the operand associated with this use, if any. */
+  Operand asUse() { none() }
+
+  /** Gets a textual representation of this element. */
+  abstract string toString();
+
+  /** Gets the block of this definition or use. */
+  abstract IRBlock getBlock();
+
+  /** Holds if this definition or use has rank `rank` in block `block`. */
+  cached
+  final predicate hasRankInBlock(IRBlock block, int rnk) {
+    block = getBlock() and
+    rnk = getRank(this, block)
+  }
+
+  /**
+   * Holds if this element is at the specified location.
+   * The location spans column `startcolumn` of line `startline` to
+   * column `endcolumn` of line `endline` in file `filepath`.
+   * For more information, see
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
+   */
+  abstract predicate hasLocationInfo(
+    string filepath, int startline, int startcolumn, int endline, int endcolumn
+  );
+}
+
+private Instruction toInstruction(DefOrUse defOrUse) {
+  result = defOrUse.asDef()
+  or
+  result = defOrUse.asUse().getUse()
+}
+
+abstract class Def extends DefOrUse {
+  Instruction store;
+
+  /** Gets the instruction of this definition. */
+  Instruction getInstruction() { result = store }
+
+  /** Gets the variable that is defined by this definition. */
+  abstract SourceVariable getVariable();
+
+  /** Holds if this definition is guaranteed to happen. */
+  abstract predicate isCertain();
+
+  override Instruction asDef() { result = this.getInstruction() }
+
+  override string toString() { result = "Def(" + store.getDumpString() + ")" }
+
+  override IRBlock getBlock() { result = this.getInstruction().getBlock() }
+
+  override predicate hasLocationInfo(
+    string filepath, int startline, int startcolumn, int endline, int endcolumn
+  ) {
+    store.getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
+  }
+}
+
+private class ExplicitDef extends Def, TExplicitDef {
+  ExplicitDef() { this = TExplicitDef(store) }
+
+  override SourceVariable getVariable() {
+    exists(VariableInstruction var |
+      explicitWrite(_, this.getInstruction(), var) and
+      result.getVariable() = var.getIRVariable() and
+      not result.isIndirection()
+    )
+  }
+
+  override predicate isCertain() { explicitWrite(true, this.getInstruction(), _) }
+}
+
+private class ParameterDef extends Def, TInitializeParam {
+  ParameterDef() { this = TInitializeParam(store) }
+
+  override SourceVariable getVariable() {
+    result.getVariable() = store.(InitializeParameterInstruction).getIRVariable() and
+    not result.isIndirection()
+    or
+    result.getVariable() = store.(InitializeIndirectionInstruction).getIRVariable() and
+    result.isIndirection()
+  }
+
+  override predicate isCertain() { any() }
+}
+
+abstract class Use extends DefOrUse {
+  Operand use;
+
+  override Operand asUse() { result = use }
+
+  /** Gets the underlying operand of this use. */
+  Operand getOperand() { result = use }
+
+  override string toString() { result = "Use(" + use.getDumpString() + ")" }
+
+  /** Gets the variable that is used by this use. */
+  abstract SourceVariable getVariable();
+
+  override IRBlock getBlock() { result = use.getUse().getBlock() }
+
+  override predicate hasLocationInfo(
+    string filepath, int startline, int startcolumn, int endline, int endcolumn
+  ) {
+    use.getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
+  }
+}
+
+private class ExplicitUse extends Use, TExplicitUse {
+  ExplicitUse() { this = TExplicitUse(use) }
+
+  override SourceVariable getVariable() {
+    exists(VariableInstruction var |
+      use.getDef() = var and
+      result.getVariable() = var.getIRVariable() and
+      (
+        if use.getUse() instanceof ReadSideEffectInstruction
+        then result.isIndirection()
+        else not result.isIndirection()
+      )
+    )
+  }
+}
+
+private class ReturnParameterIndirection extends Use, TReturnParamIndirection {
+  ReturnParameterIndirection() { this = TReturnParamIndirection(use) }
+
+  override SourceVariable getVariable() {
+    exists(ReturnIndirectionInstruction ret |
+      returnParameterIndirection(use, ret) and
+      result.getVariable() = ret.getIRVariable() and
+      result.isIndirection()
+    )
+  }
+}
+
+private predicate isExplicitUse(Operand op) {
+  op.getDef() instanceof VariableAddressInstruction and
+  not exists(LoadInstruction load |
+    load.getSourceAddressOperand() = op and
+    load.getAUse().getUse() instanceof InitializeIndirectionInstruction
+  )
+}
+
+private predicate returnParameterIndirection(Operand op, ReturnIndirectionInstruction ret) {
+  ret.getSourceAddressOperand() = op
+}
+
+/**
+ * Holds if `iFrom` computes an address that is used by `iTo`.
+ */
+predicate addressFlow(Instruction iFrom, Instruction iTo) {
+  iTo.(CopyValueInstruction).getSourceValue() = iFrom
+  or
+  iTo.(ConvertInstruction).getUnary() = iFrom
+  or
+  iTo.(CheckedConvertOrNullInstruction).getUnary() = iFrom
+  or
+  iTo.(InheritanceConversionInstruction).getUnary() = iFrom
+  or
+  iTo.(PointerArithmeticInstruction).getLeft() = iFrom
+  or
+  iTo.(FieldAddressInstruction).getObjectAddress() = iFrom
+  or
+  iTo.(LoadInstruction).getSourceAddress() = iFrom
+  or
+  exists(WriteSideEffectInstruction write |
+    write.getPrimaryInstruction() = iTo and
+    write.getDestinationAddress() = iFrom
+  )
+}
+
+/**
+ * The reflexive, transitive closure of `addressFlow` that ends as the address of a
+ * store or read operation.
+ */
+cached
+predicate addressFlowTC(Instruction iFrom, Instruction iTo) {
+  iTo = [getDestinationAddress(_), getSourceAddress(_)] and
+  addressFlow*(iFrom, iTo)
+}
+
+/**
+ * Gets the destination address of `instr` if it is a `StoreInstruction` or
+ * a `WriteSideEffectInstruction`. The destination address of a `WriteSideEffectInstruction` is adjusted
+ * in the case of calls to operator `new` to give the destination address of a subsequent store (if any).
+ */
+Instruction getDestinationAddress(Instruction instr) {
+  result =
+    [
+      instr.(StoreInstruction).getDestinationAddress(),
+      instr.(WriteSideEffectInstruction).getDestinationAddress()
+    ]
+}
+
+class ReferenceToInstruction extends CopyValueInstruction {
+  ReferenceToInstruction() {
+    this.getResultType() instanceof Cpp::ReferenceType and
+    not this.getUnary().getResultType() instanceof Cpp::ReferenceType
+  }
+
+  Instruction getSourceAddress() { result = getSourceAddressOperand().getDef() }
+
+  Operand getSourceAddressOperand() { result = this.getUnaryOperand() }
+}
+
+/** Gets the source address of `instr` if it is an instruction that behaves like a `LoadInstruction`. */
+Instruction getSourceAddress(Instruction instr) { result = getSourceAddressOperand(instr).getDef() }
+
+/**
+ * Gets the operand that represents the source address of `instr` if it is an
+ * instruction that behaves like a `LoadInstruction`.
+ */
+Operand getSourceAddressOperand(Instruction instr) {
+  result =
+    [
+      instr.(LoadInstruction).getSourceAddressOperand(),
+      instr.(ReadSideEffectInstruction).getArgumentOperand(),
+      instr.(ReferenceToInstruction).getSourceAddressOperand()
+    ]
+}
+
+/**
+ * Gets the source address of `node` if it's an instruction or operand that
+ * behaves like a `LoadInstruction`.
+ */
+Instruction getSourceAddressFromNode(Node node) {
+  result = getSourceAddress(node.asInstruction())
+  or
+  result = getSourceAddress(node.asOperand().(SideEffectOperand).getUse())
+}
+
+/** Gets the source value of `instr` if it's an instruction that behaves like a `LoadInstruction`. */
+Instruction getSourceValue(Instruction instr) { result = getSourceValueOperand(instr).getDef() }
+
+/**
+ * Gets the operand that represents the source value of `instr` if it's an instruction
+ * that behaves like a `LoadInstruction`.
+ */
+Operand getSourceValueOperand(Instruction instr) {
+  result = instr.(LoadInstruction).getSourceValueOperand()
+  or
+  result = instr.(ReadSideEffectInstruction).getSideEffectOperand()
+  or
+  result = instr.(ReferenceToInstruction).getSourceValueOperand()
+}
+
+/**
+ * Holds if `instr` is a `StoreInstruction` or a `WriteSideEffectInstruction` that writes to an address.
+ * The addresses is computed using `address`, and `certain` is `true` if the write is guaranteed to overwrite
+ * the entire variable.
+ */
+cached
+predicate explicitWrite(boolean certain, Instruction instr, Instruction address) {
+  exists(StoreInstruction store |
+    store = instr and addressFlowTC(address, store.getDestinationAddress())
+  |
+    if
+      addressFlowTC(any(Instruction i |
+          i instanceof FieldAddressInstruction or i instanceof PointerArithmeticInstruction
+        ), store.getDestinationAddress())
+    then certain = false
+    else certain = true
+  )
+  or
+  addressFlowTC(address, instr.(WriteSideEffectInstruction).getDestinationAddress()) and
+  certain = false
+}
+
+cached
+private module Cached {
+  /**
+   * Holds if `nodeFrom` is a read or write, and `nTo` is the next subsequent read of the variable
+   * written (or read) by `storeOrRead`.
+   */
+  cached
+  predicate ssaFlow(Node nodeFrom, Node nodeTo) {
+    // Def-use/use-use flow from an `InstructionNode` to an `OperandNode`.
+    exists(IRBlock bb1, int i1, IRBlock bb2, int i2, DefOrUse defOrUse, Use use, SourceVariable v |
+      defOrUse.hasRankInBlock(bb1, i1) and
+      use.hasRankInBlock(bb2, i2) and
+      use.getVariable() = v and
+      adjacentDefRead(_, bb1, i1, bb2, i2) and
+      nodeFrom.asInstruction() = toInstruction(defOrUse) and
+      flowOutOfAddressStep(use.getOperand(), nodeTo)
+    )
+    or
+    // Use-use flow from a `ReadNode` to an `OperandNode`.
+    exists(ReadNode read, IRBlock bb1, int i1, IRBlock bb2, int i2, Use use1, Use use2 |
+      read = nodeFrom and
+      use1.hasRankInBlock(bb1, i1) and
+      use2.hasRankInBlock(bb2, i2) and
+      use1.getOperand().getDef() = read.getInstruction() and
+      adjacentDefRead(_, bb1, i1, bb2, i2) and
+      flowOutOfAddressStep(use2.getOperand(), nodeTo)
+    )
+    or
+    // Flow from phi nodes
+    exists(PhiNode phi, Use use, IRBlock block, int rnk |
+      phi = nodeFrom.(SsaPhiNode).getPhiNode() and
+      use.hasRankInBlock(block, rnk) and
+      phi.getSourceVariable() = use.getVariable() and
+      flowOutOfAddressStep(use.getOperand(), nodeTo) and
+      adjacentDefRead(_, phi.getBasicBlock(), -1, block, rnk)
+    )
+    or
+    // Flow to phi nodes
+    exists(Def def, StoreNode store, IRBlock block, int rnk |
+      store = nodeFrom and
+      store.isTerminal() and
+      def.getInstruction() = store.getStoreInstruction() and
+      def.hasRankInBlock(block, rnk) and
+      nodeTo.(SsaPhiNode).hasInputAtRankInBlock(block, rnk)
+    )
+    or
+    // Def-use flow from a `StoreNode` to an `OperandNode`.
+    exists(
+      StoreNode store, IRBlock bb1, int i1, IRBlock bb2, int i2, Def def, Use use, Definition ssaDef
+    |
+      store = nodeFrom and
+      store.isTerminal() and
+      def.getInstruction() = store.getStoreInstruction() and
+      def.hasRankInBlock(bb1, i1) and
+      adjacentDefRead(ssaDef, bb1, i1, bb2, i2) and
+      use.hasRankInBlock(bb2, i2) and
+      flowOutOfAddressStep(use.getOperand(), nodeTo)
+    )
+    or
+    // This final case is a bit annoying. The write side effect on an expression like `a = new A;` writes
+    // to a fresh address returned by `operator new`, and there's no easy way to use the shared SSA
+    // library to hook that up to the assignment to `a`. So instead we flow to the _first_ use of the
+    // value computed by `operator new` that occurs after `nodeFrom` (to avoid a loop in the
+    // dataflow graph).
+    exists(
+      StoreNode store, WriteSideEffectInstruction write, IRBlock bb, int i1, int i2, Operand op
+    |
+      store = nodeFrom and
+      store.getInstruction().(CallInstruction).getStaticCallTarget() instanceof
+        Alloc::OperatorNewAllocationFunction and
+      write = store.getStoreInstruction() and
+      bb.getInstruction(i1) = write and
+      bb.getInstruction(i2) = op.getUse() and
+      // Flow to an instruction that occurs later in the block.
+      valueFlow*(store.getInstruction(), op.getDef()) and
+      nodeTo.asOperand() = op and
+      i2 > i1 and
+      // There is no previous instruction that also occurs after `nodeFrom`.
+      not exists(Instruction instr, int i |
+        bb.getInstruction(i) = instr and
+        valueFlow(instr, op.getDef()) and
+        i1 < i and
+        i < i2
+      )
+    )
+  }
+
+  private predicate valueFlow(Instruction iFrom, Instruction iTo) {
+    iTo.(CopyValueInstruction).getSourceValue() = iFrom
+    or
+    iTo.(ConvertInstruction).getUnary() = iFrom
+    or
+    iTo.(CheckedConvertOrNullInstruction).getUnary() = iFrom
+    or
+    iTo.(InheritanceConversionInstruction).getUnary() = iFrom
+  }
+
+  pragma[noinline]
+  private predicate callTargetHasInputOutput(
+    CallInstruction call, DataFlow::FunctionInput input, DataFlow::FunctionOutput output
+  ) {
+    exists(DataFlow::DataFlowFunction func |
+      call.getStaticCallTarget() = func and
+      func.hasDataFlow(input, output)
+    )
+  }
+
+  private predicate flowOutOfAddressStep(Operand operand, Node nTo) {
+    // Flow into a read node
+    exists(ReadNode readNode | readNode = nTo |
+      readNode.isInitial() and
+      operand.getDef() = readNode.getInstruction()
+    )
+    or
+    exists(StoreNode storeNode, Instruction def |
+      storeNode = nTo and
+      def = operand.getDef()
+    |
+      storeNode.isTerminal() and
+      not addressFlow(def, _) and
+      // Only transfer flow to a store node if it doesn't immediately overwrite the address
+      // we've just written to.
+      explicitWrite(false, storeNode.getStoreInstruction(), def)
+    )
+    or
+    operand = getSourceAddressOperand(nTo.asInstruction())
+    or
+    exists(ReturnIndirectionInstruction ret |
+      ret.getSourceAddressOperand() = operand and
+      ret = nTo.asInstruction()
+    )
+    or
+    exists(ReturnValueInstruction ret |
+      ret.getReturnAddressOperand() = operand and
+      nTo.asInstruction() = ret
+    )
+    or
+    exists(CallInstruction call, int index, ReadSideEffectInstruction read |
+      call.getArgumentOperand(index) = operand and
+      read = getSideEffectFor(call, index) and
+      nTo.asOperand() = read.getSideEffectOperand()
+    )
+    or
+    exists(CopyInstruction copy |
+      not exists(getSourceAddressOperand(copy)) and
+      copy.getSourceValueOperand() = operand and
+      flowOutOfAddressStep(copy.getAUse(), nTo)
+    )
+    or
+    exists(ConvertInstruction convert |
+      convert.getUnaryOperand() = operand and
+      flowOutOfAddressStep(convert.getAUse(), nTo)
+    )
+    or
+    exists(CheckedConvertOrNullInstruction convert |
+      convert.getUnaryOperand() = operand and
+      flowOutOfAddressStep(convert.getAUse(), nTo)
+    )
+    or
+    exists(InheritanceConversionInstruction convert |
+      convert.getUnaryOperand() = operand and
+      flowOutOfAddressStep(convert.getAUse(), nTo)
+    )
+    or
+    exists(PointerArithmeticInstruction arith |
+      arith.getLeftOperand() = operand and
+      flowOutOfAddressStep(arith.getAUse(), nTo)
+    )
+    or
+    // Flow through a modelled function that has parameter -> return value flow.
+    exists(
+      CallInstruction call, int index, DataFlow::FunctionInput input,
+      DataFlow::FunctionOutput output
+    |
+      callTargetHasInputOutput(call, input, output) and
+      call.getArgumentOperand(index) = operand and
+      not getSideEffectFor(call, index) instanceof ReadSideEffectInstruction and
+      input.isParameter(index) and
+      output.isReturnValue() and
+      flowOutOfAddressStep(call.getAUse(), nTo)
+    )
+  }
+}
+
+import Cached

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaImplCommon.qll

@@ -0,0 +1,637 @@
+/**
+ * Provides a language-independent implementation of static single assignment
+ * (SSA) form.
+ */
+
+private import SsaImplSpecific
+
+private BasicBlock getABasicBlockPredecessor(BasicBlock bb) { getABasicBlockSuccessor(result) = bb }
+
+/**
+ * Liveness analysis (based on source variables) to restrict the size of the
+ * SSA representation.
+ */
+private module Liveness {
+  /**
+   * A classification of variable references into reads (of a given kind) and
+   * (certain or uncertain) writes.
+   */
+  private newtype TRefKind =
+    Read(boolean certain) { certain in [false, true] } or
+    Write(boolean certain) { certain in [false, true] }
+
+  private class RefKind extends TRefKind {
+    string toString() {
+      exists(boolean certain | this = Read(certain) and result = "read (" + certain + ")")
+      or
+      exists(boolean certain | this = Write(certain) and result = "write (" + certain + ")")
+    }
+
+    int getOrder() {
+      this = Read(_) and
+      result = 0
+      or
+      this = Write(_) and
+      result = 1
+    }
+  }
+
+  /**
+   * Holds if the `i`th node of basic block `bb` is a reference to `v` of kind `k`.
+   */
+  private predicate ref(BasicBlock bb, int i, SourceVariable v, RefKind k) {
+    exists(boolean certain | variableRead(bb, i, v, certain) | k = Read(certain))
+    or
+    exists(boolean certain | variableWrite(bb, i, v, certain) | k = Write(certain))
+  }
+
+  private newtype OrderedRefIndex =
+    MkOrderedRefIndex(int i, int tag) {
+      exists(RefKind rk | ref(_, i, _, rk) | tag = rk.getOrder())
+    }
+
+  private OrderedRefIndex refOrd(BasicBlock bb, int i, SourceVariable v, RefKind k, int ord) {
+    ref(bb, i, v, k) and
+    result = MkOrderedRefIndex(i, ord) and
+    ord = k.getOrder()
+  }
+
+  /**
+   * Gets the (1-based) rank of the reference to `v` at the `i`th node of
+   * basic block `bb`, which has the given reference kind `k`.
+   *
+   * Reads are considered before writes when they happen at the same index.
+   */
+  private int refRank(BasicBlock bb, int i, SourceVariable v, RefKind k) {
+    refOrd(bb, i, v, k, _) =
+      rank[result](int j, int ord, OrderedRefIndex res |
+        res = refOrd(bb, j, v, _, ord)
+      |
+        res order by j, ord
+      )
+  }
+
+  private int maxRefRank(BasicBlock bb, SourceVariable v) {
+    result = refRank(bb, _, v, _) and
+    not result + 1 = refRank(bb, _, v, _)
+  }
+
+  /**
+   * Gets the (1-based) rank of the first reference to `v` inside basic block `bb`
+   * that is either a read or a certain write.
+   */
+  private int firstReadOrCertainWrite(BasicBlock bb, SourceVariable v) {
+    result =
+      min(int r, RefKind k |
+        r = refRank(bb, _, v, k) and
+        k != Write(false)
+      |
+        r
+      )
+  }
+
+  /**
+   * Holds if source variable `v` is live at the beginning of basic block `bb`.
+   */
+  predicate liveAtEntry(BasicBlock bb, SourceVariable v) {
+    // The first read or certain write to `v` inside `bb` is a read
+    refRank(bb, _, v, Read(_)) = firstReadOrCertainWrite(bb, v)
+    or
+    // There is no certain write to `v` inside `bb`, but `v` is live at entry
+    // to a successor basic block of `bb`
+    not exists(firstReadOrCertainWrite(bb, v)) and
+    liveAtExit(bb, v)
+  }
+
+  /**
+   * Holds if source variable `v` is live at the end of basic block `bb`.
+   */
+  predicate liveAtExit(BasicBlock bb, SourceVariable v) {
+    liveAtEntry(getABasicBlockSuccessor(bb), v)
+  }
+
+  /**
+   * Holds if variable `v` is live in basic block `bb` at index `i`.
+   * The rank of `i` is `rnk` as defined by `refRank()`.
+   */
+  private predicate liveAtRank(BasicBlock bb, int i, SourceVariable v, int rnk) {
+    exists(RefKind kind | rnk = refRank(bb, i, v, kind) |
+      rnk = maxRefRank(bb, v) and
+      liveAtExit(bb, v)
+      or
+      ref(bb, i, v, kind) and
+      kind = Read(_)
+      or
+      exists(RefKind nextKind |
+        liveAtRank(bb, _, v, rnk + 1) and
+        rnk + 1 = refRank(bb, _, v, nextKind) and
+        nextKind != Write(true)
+      )
+    )
+  }
+
+  /**
+   * Holds if variable `v` is live after the (certain or uncertain) write at
+   * index `i` inside basic block `bb`.
+   */
+  predicate liveAfterWrite(BasicBlock bb, int i, SourceVariable v) {
+    exists(int rnk | rnk = refRank(bb, i, v, Write(_)) | liveAtRank(bb, i, v, rnk))
+  }
+}
+
+private import Liveness
+
+/** Holds if `bb1` strictly dominates `bb2`. */
+private predicate strictlyDominates(BasicBlock bb1, BasicBlock bb2) {
+  bb1 = getImmediateBasicBlockDominator+(bb2)
+}
+
+/** Holds if `bb1` dominates a predecessor of `bb2`. */
+private predicate dominatesPredecessor(BasicBlock bb1, BasicBlock bb2) {
+  exists(BasicBlock pred | pred = getABasicBlockPredecessor(bb2) |
+    bb1 = pred
+    or
+    strictlyDominates(bb1, pred)
+  )
+}
+
+/** Holds if `df` is in the dominance frontier of `bb`. */
+private predicate inDominanceFrontier(BasicBlock bb, BasicBlock df) {
+  dominatesPredecessor(bb, df) and
+  not strictlyDominates(bb, df)
+}
+
+/**
+ * Holds if `bb` is in the dominance frontier of a block containing a
+ * definition of `v`.
+ */
+pragma[noinline]
+private predicate inDefDominanceFrontier(BasicBlock bb, SourceVariable v) {
+  exists(BasicBlock defbb, Definition def |
+    def.definesAt(v, defbb, _) and
+    inDominanceFrontier(defbb, bb)
+  )
+}
+
+cached
+newtype TDefinition =
+  TWriteDef(SourceVariable v, BasicBlock bb, int i) {
+    variableWrite(bb, i, v, _) and
+    liveAfterWrite(bb, i, v)
+  } or
+  TPhiNode(SourceVariable v, BasicBlock bb) {
+    inDefDominanceFrontier(bb, v) and
+    liveAtEntry(bb, v)
+  }
+
+private module SsaDefReaches {
+  newtype TSsaRefKind =
+    SsaRead() or
+    SsaDef()
+
+  /**
+   * A classification of SSA variable references into reads and definitions.
+   */
+  class SsaRefKind extends TSsaRefKind {
+    string toString() {
+      this = SsaRead() and
+      result = "SsaRead"
+      or
+      this = SsaDef() and
+      result = "SsaDef"
+    }
+
+    int getOrder() {
+      this = SsaRead() and
+      result = 0
+      or
+      this = SsaDef() and
+      result = 1
+    }
+  }
+
+  /**
+   * Holds if the `i`th node of basic block `bb` is a reference to `v`,
+   * either a read (when `k` is `SsaRead()`) or an SSA definition (when `k`
+   * is `SsaDef()`).
+   *
+   * Unlike `Liveness::ref`, this includes `phi` nodes.
+   */
+  predicate ssaRef(BasicBlock bb, int i, SourceVariable v, SsaRefKind k) {
+    variableRead(bb, i, v, _) and
+    k = SsaRead()
+    or
+    exists(Definition def | def.definesAt(v, bb, i)) and
+    k = SsaDef()
+  }
+
+  private newtype OrderedSsaRefIndex =
+    MkOrderedSsaRefIndex(int i, SsaRefKind k) { ssaRef(_, i, _, k) }
+
+  private OrderedSsaRefIndex ssaRefOrd(BasicBlock bb, int i, SourceVariable v, SsaRefKind k, int ord) {
+    ssaRef(bb, i, v, k) and
+    result = MkOrderedSsaRefIndex(i, k) and
+    ord = k.getOrder()
+  }
+
+  /**
+   * Gets the (1-based) rank of the reference to `v` at the `i`th node of basic
+   * block `bb`, which has the given reference kind `k`.
+   *
+   * For example, if `bb` is a basic block with a phi node for `v` (considered
+   * to be at index -1), reads `v` at node 2, and defines it at node 5, we have:
+   *
+   * ```ql
+   * ssaRefRank(bb, -1, v, SsaDef()) = 1    // phi node
+   * ssaRefRank(bb,  2, v, Read())   = 2    // read at node 2
+   * ssaRefRank(bb,  5, v, SsaDef()) = 3    // definition at node 5
+   * ```
+   *
+   * Reads are considered before writes when they happen at the same index.
+   */
+  int ssaRefRank(BasicBlock bb, int i, SourceVariable v, SsaRefKind k) {
+    ssaRefOrd(bb, i, v, k, _) =
+      rank[result](int j, int ord, OrderedSsaRefIndex res |
+        res = ssaRefOrd(bb, j, v, _, ord)
+      |
+        res order by j, ord
+      )
+  }
+
+  int maxSsaRefRank(BasicBlock bb, SourceVariable v) {
+    result = ssaRefRank(bb, _, v, _) and
+    not result + 1 = ssaRefRank(bb, _, v, _)
+  }
+
+  /**
+   * Holds if the SSA definition `def` reaches rank index `rnk` in its own
+   * basic block `bb`.
+   */
+  predicate ssaDefReachesRank(BasicBlock bb, Definition def, int rnk, SourceVariable v) {
+    exists(int i |
+      rnk = ssaRefRank(bb, i, v, SsaDef()) and
+      def.definesAt(v, bb, i)
+    )
+    or
+    ssaDefReachesRank(bb, def, rnk - 1, v) and
+    rnk = ssaRefRank(bb, _, v, SsaRead())
+  }
+
+  /**
+   * Holds if the SSA definition of `v` at `def` reaches index `i` in the same
+   * basic block `bb`, without crossing another SSA definition of `v`.
+   */
+  predicate ssaDefReachesReadWithinBlock(SourceVariable v, Definition def, BasicBlock bb, int i) {
+    exists(int rnk |
+      ssaDefReachesRank(bb, def, rnk, v) and
+      rnk = ssaRefRank(bb, i, v, SsaRead())
+    )
+  }
+
+  /**
+   * Holds if the SSA definition of `v` at `def` reaches uncertain SSA definition
+   * `redef` in the same basic block, without crossing another SSA definition of `v`.
+   */
+  predicate ssaDefReachesUncertainDefWithinBlock(
+    SourceVariable v, Definition def, UncertainWriteDefinition redef
+  ) {
+    exists(BasicBlock bb, int rnk, int i |
+      ssaDefReachesRank(bb, def, rnk, v) and
+      rnk = ssaRefRank(bb, i, v, SsaDef()) - 1 and
+      redef.definesAt(v, bb, i)
+    )
+  }
+
+  /**
+   * Same as `ssaRefRank()`, but restricted to a particular SSA definition `def`.
+   */
+  int ssaDefRank(Definition def, SourceVariable v, BasicBlock bb, int i, SsaRefKind k) {
+    v = def.getSourceVariable() and
+    result = ssaRefRank(bb, i, v, k) and
+    (
+      ssaDefReachesRead(_, def, bb, i)
+      or
+      def.definesAt(_, bb, i)
+    )
+  }
+
+  /**
+   * Holds if the reference to `def` at index `i` in basic block `bb` is the
+   * last reference to `v` inside `bb`.
+   */
+  pragma[noinline]
+  predicate lastSsaRef(Definition def, SourceVariable v, BasicBlock bb, int i) {
+    ssaDefRank(def, v, bb, i, _) = maxSsaRefRank(bb, v)
+  }
+
+  predicate defOccursInBlock(Definition def, BasicBlock bb, SourceVariable v) {
+    exists(ssaDefRank(def, v, bb, _, _))
+  }
+
+  pragma[noinline]
+  private predicate ssaDefReachesThroughBlock(Definition def, BasicBlock bb) {
+    ssaDefReachesEndOfBlock(bb, def, _) and
+    not defOccursInBlock(_, bb, def.getSourceVariable())
+  }
+
+  /**
+   * Holds if `def` is accessed in basic block `bb1` (either a read or a write),
+   * `bb2` is a transitive successor of `bb1`, `def` is live at the end of `bb1`,
+   * and the underlying variable for `def` is neither read nor written in any block
+   * on the path between `bb1` and `bb2`.
+   */
+  predicate varBlockReaches(Definition def, BasicBlock bb1, BasicBlock bb2) {
+    defOccursInBlock(def, bb1, _) and
+    bb2 = getABasicBlockSuccessor(bb1)
+    or
+    exists(BasicBlock mid |
+      varBlockReaches(def, bb1, mid) and
+      ssaDefReachesThroughBlock(def, mid) and
+      bb2 = getABasicBlockSuccessor(mid)
+    )
+  }
+
+  /**
+   * Holds if `def` is accessed in basic block `bb1` (either a read or a write),
+   * `def` is read at index `i2` in basic block `bb2`, `bb2` is in a transitive
+   * successor block of `bb1`, and `def` is neither read nor written in any block
+   * on a path between `bb1` and `bb2`.
+   */
+  predicate defAdjacentRead(Definition def, BasicBlock bb1, BasicBlock bb2, int i2) {
+    varBlockReaches(def, bb1, bb2) and
+    ssaRefRank(bb2, i2, def.getSourceVariable(), SsaRead()) = 1
+  }
+}
+
+private import SsaDefReaches
+
+pragma[nomagic]
+predicate liveThrough(BasicBlock bb, SourceVariable v) {
+  liveAtExit(bb, v) and
+  not ssaRef(bb, _, v, SsaDef())
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Holds if the SSA definition of `v` at `def` reaches the end of basic
+ * block `bb`, at which point it is still live, without crossing another
+ * SSA definition of `v`.
+ */
+pragma[nomagic]
+predicate ssaDefReachesEndOfBlock(BasicBlock bb, Definition def, SourceVariable v) {
+  exists(int last | last = maxSsaRefRank(bb, v) |
+    ssaDefReachesRank(bb, def, last, v) and
+    liveAtExit(bb, v)
+  )
+  or
+  // The construction of SSA form ensures that each read of a variable is
+  // dominated by its definition. An SSA definition therefore reaches a
+  // control flow node if it is the _closest_ SSA definition that dominates
+  // the node. If two definitions dominate a node then one must dominate the
+  // other, so therefore the definition of _closest_ is given by the dominator
+  // tree. Thus, reaching definitions can be calculated in terms of dominance.
+  ssaDefReachesEndOfBlock(getImmediateBasicBlockDominator(bb), def, pragma[only_bind_into](v)) and
+  liveThrough(bb, pragma[only_bind_into](v))
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Holds if `inp` is an input to the phi node `phi` along the edge originating in `bb`.
+ */
+pragma[nomagic]
+predicate phiHasInputFromBlock(PhiNode phi, Definition inp, BasicBlock bb) {
+  exists(SourceVariable v, BasicBlock bbDef |
+    phi.definesAt(v, bbDef, _) and
+    getABasicBlockPredecessor(bbDef) = bb and
+    ssaDefReachesEndOfBlock(bb, inp, v)
+  )
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Holds if the SSA definition of `v` at `def` reaches a read at index `i` in
+ * basic block `bb`, without crossing another SSA definition of `v`. The read
+ * is of kind `rk`.
+ */
+pragma[nomagic]
+predicate ssaDefReachesRead(SourceVariable v, Definition def, BasicBlock bb, int i) {
+  ssaDefReachesReadWithinBlock(v, def, bb, i)
+  or
+  variableRead(bb, i, v, _) and
+  ssaDefReachesEndOfBlock(getABasicBlockPredecessor(bb), def, v) and
+  not ssaDefReachesReadWithinBlock(v, _, bb, i)
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Holds if `def` is accessed at index `i1` in basic block `bb1` (either a read
+ * or a write), `def` is read at index `i2` in basic block `bb2`, and there is a
+ * path between them without any read of `def`.
+ */
+pragma[nomagic]
+predicate adjacentDefRead(Definition def, BasicBlock bb1, int i1, BasicBlock bb2, int i2) {
+  exists(int rnk |
+    rnk = ssaDefRank(def, _, bb1, i1, _) and
+    rnk + 1 = ssaDefRank(def, _, bb1, i2, SsaRead()) and
+    variableRead(bb1, i2, _, _) and
+    bb2 = bb1
+  )
+  or
+  lastSsaRef(def, _, bb1, i1) and
+  defAdjacentRead(def, bb1, bb2, i2)
+}
+
+pragma[noinline]
+private predicate adjacentDefRead(
+  Definition def, BasicBlock bb1, int i1, BasicBlock bb2, int i2, SourceVariable v
+) {
+  adjacentDefRead(def, bb1, i1, bb2, i2) and
+  v = def.getSourceVariable()
+}
+
+private predicate adjacentDefReachesRead(
+  Definition def, BasicBlock bb1, int i1, BasicBlock bb2, int i2
+) {
+  exists(SourceVariable v | adjacentDefRead(def, bb1, i1, bb2, i2, v) |
+    ssaRef(bb1, i1, v, SsaDef())
+    or
+    variableRead(bb1, i1, v, true)
+  )
+  or
+  exists(BasicBlock bb3, int i3 |
+    adjacentDefReachesRead(def, bb1, i1, bb3, i3) and
+    variableRead(bb3, i3, _, false) and
+    adjacentDefRead(def, bb3, i3, bb2, i2)
+  )
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Same as `adjacentDefRead`, but ignores uncertain reads.
+ */
+pragma[nomagic]
+predicate adjacentDefNoUncertainReads(Definition def, BasicBlock bb1, int i1, BasicBlock bb2, int i2) {
+  adjacentDefReachesRead(def, bb1, i1, bb2, i2) and
+  variableRead(bb2, i2, _, true)
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Holds if the node at index `i` in `bb` is a last reference to SSA definition
+ * `def`. The reference is last because it can reach another write `next`,
+ * without passing through another read or write.
+ */
+pragma[nomagic]
+predicate lastRefRedef(Definition def, BasicBlock bb, int i, Definition next) {
+  exists(SourceVariable v |
+    // Next reference to `v` inside `bb` is a write
+    exists(int rnk, int j |
+      rnk = ssaDefRank(def, v, bb, i, _) and
+      next.definesAt(v, bb, j) and
+      rnk + 1 = ssaRefRank(bb, j, v, SsaDef())
+    )
+    or
+    // Can reach a write using one or more steps
+    lastSsaRef(def, v, bb, i) and
+    exists(BasicBlock bb2 |
+      varBlockReaches(def, bb, bb2) and
+      1 = ssaDefRank(next, v, bb2, _, SsaDef())
+    )
+  )
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Holds if `inp` is an immediately preceding definition of uncertain definition
+ * `def`. Since `def` is uncertain, the value from the preceding definition might
+ * still be valid.
+ */
+pragma[nomagic]
+predicate uncertainWriteDefinitionInput(UncertainWriteDefinition def, Definition inp) {
+  lastRefRedef(inp, _, _, def)
+}
+
+private predicate adjacentDefReachesUncertainRead(
+  Definition def, BasicBlock bb1, int i1, BasicBlock bb2, int i2
+) {
+  adjacentDefReachesRead(def, bb1, i1, bb2, i2) and
+  variableRead(bb2, i2, _, false)
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Same as `lastRefRedef`, but ignores uncertain reads.
+ */
+pragma[nomagic]
+predicate lastRefRedefNoUncertainReads(Definition def, BasicBlock bb, int i, Definition next) {
+  lastRefRedef(def, bb, i, next) and
+  not variableRead(bb, i, def.getSourceVariable(), false)
+  or
+  exists(BasicBlock bb0, int i0 |
+    lastRefRedef(def, bb0, i0, next) and
+    adjacentDefReachesUncertainRead(def, bb, i, bb0, i0)
+  )
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Holds if the node at index `i` in `bb` is a last reference to SSA
+ * definition `def`.
+ *
+ * That is, the node can reach the end of the enclosing callable, or another
+ * SSA definition for the underlying source variable, without passing through
+ * another read.
+ */
+pragma[nomagic]
+predicate lastRef(Definition def, BasicBlock bb, int i) {
+  lastRefRedef(def, bb, i, _)
+  or
+  lastSsaRef(def, _, bb, i) and
+  (
+    // Can reach exit directly
+    bb instanceof ExitBasicBlock
+    or
+    // Can reach a block using one or more steps, where `def` is no longer live
+    exists(BasicBlock bb2 | varBlockReaches(def, bb, bb2) |
+      not defOccursInBlock(def, bb2, _) and
+      not ssaDefReachesEndOfBlock(bb2, def, _)
+    )
+  )
+}
+
+/**
+ * NB: If this predicate is exposed, it should be cached.
+ *
+ * Same as `lastRefRedef`, but ignores uncertain reads.
+ */
+pragma[nomagic]
+predicate lastRefNoUncertainReads(Definition def, BasicBlock bb, int i) {
+  lastRef(def, bb, i) and
+  not variableRead(bb, i, def.getSourceVariable(), false)
+  or
+  exists(BasicBlock bb0, int i0 |
+    lastRef(def, bb0, i0) and
+    adjacentDefReachesUncertainRead(def, bb, i, bb0, i0)
+  )
+}
+
+/** A static single assignment (SSA) definition. */
+class Definition extends TDefinition {
+  /** Gets the source variable underlying this SSA definition. */
+  SourceVariable getSourceVariable() { this.definesAt(result, _, _) }
+
+  /**
+   * Holds if this SSA definition defines `v` at index `i` in basic block `bb`.
+   * Phi nodes are considered to be at index `-1`, while normal variable writes
+   * are at the index of the control flow node they wrap.
+   */
+  final predicate definesAt(SourceVariable v, BasicBlock bb, int i) {
+    this = TWriteDef(v, bb, i)
+    or
+    this = TPhiNode(v, bb) and i = -1
+  }
+
+  /** Gets the basic block to which this SSA definition belongs. */
+  final BasicBlock getBasicBlock() { this.definesAt(_, result, _) }
+
+  /** Gets a textual representation of this SSA definition. */
+  string toString() { none() }
+}
+
+/** An SSA definition that corresponds to a write. */
+class WriteDefinition extends Definition, TWriteDef {
+  private SourceVariable v;
+  private BasicBlock bb;
+  private int i;
+
+  WriteDefinition() { this = TWriteDef(v, bb, i) }
+
+  override string toString() { result = "WriteDef" }
+}
+
+/** A phi node. */
+class PhiNode extends Definition, TPhiNode {
+  override string toString() { result = "Phi" }
+}
+
+/**
+ * An SSA definition that represents an uncertain update of the underlying
+ * source variable.
+ */
+class UncertainWriteDefinition extends WriteDefinition {
+  UncertainWriteDefinition() {
+    exists(SourceVariable v, BasicBlock bb, int i |
+      this.definesAt(v, bb, i) and
+      variableWrite(bb, i, v, false)
+    )
+  }
+}

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaImplSpecific.qll

@@ -0,0 +1,64 @@
+private import semmle.code.cpp.ir.IR
+private import DataFlowUtil
+private import DataFlowPrivate
+private import DataFlowImplCommon as DataFlowImplCommon
+private import Ssa as Ssa
+
+class BasicBlock = IRBlock;
+
+BasicBlock getImmediateBasicBlockDominator(BasicBlock bb) { result.immediatelyDominates(bb) }
+
+BasicBlock getABasicBlockSuccessor(BasicBlock bb) { result = bb.getASuccessor() }
+
+class ExitBasicBlock extends IRBlock {
+  ExitBasicBlock() { this.getLastInstruction() instanceof ExitFunctionInstruction }
+}
+
+private newtype TSourceVariable =
+  TSourceIRVariable(IRVariable var) or
+  TSourceIRVariableIndirection(InitializeIndirectionInstruction init)
+
+abstract class SourceVariable extends TSourceVariable {
+  IRVariable var;
+
+  IRVariable getVariable() { result = var }
+
+  abstract string toString();
+
+  predicate isIndirection() { none() }
+}
+
+class SourceIRVariable extends SourceVariable, TSourceIRVariable {
+  SourceIRVariable() { this = TSourceIRVariable(var) }
+
+  override string toString() { result = this.getVariable().toString() }
+}
+
+class SourceIRVariableIndirection extends SourceVariable, TSourceIRVariableIndirection {
+  InitializeIndirectionInstruction init;
+
+  SourceIRVariableIndirection() {
+    this = TSourceIRVariableIndirection(init) and var = init.getIRVariable()
+  }
+
+  override string toString() { result = "*" + this.getVariable().toString() }
+
+  override predicate isIndirection() { any() }
+}
+
+predicate variableWrite(BasicBlock bb, int i, SourceVariable v, boolean certain) {
+  DataFlowImplCommon::forceCachingInSameStage() and
+  exists(Ssa::Def def |
+    def.hasRankInBlock(bb, i) and
+    v = def.getVariable() and
+    (if def.isCertain() then certain = true else certain = false)
+  )
+}
+
+predicate variableRead(BasicBlock bb, int i, SourceVariable v, boolean certain) {
+  exists(Ssa::Use use |
+    use.hasRankInBlock(bb, i) and
+    v = use.getVariable() and
+    certain = true
+  )
+}

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/TaintTrackingUtil.qll

@@ -44,8 +44,6 @@ private predicate instructionToOperandTaintStep(Instruction fromInstr, Operand t
     fromInstr = readInstr.getArgumentDef() and
     toOperand = readInstr.getSideEffectOperand()
   )
-  or
-  toOperand.(LoadOperand).getAnyDef() = fromInstr
 }
 
 /**
@@ -84,8 +82,6 @@ private predicate operandToInstructionTaintStep(Operand opFrom, Instruction inst
     instrTo.(FieldAddressInstruction).getField().getDeclaringType() instanceof Union
   )
   or
-  instrTo.(LoadInstruction).getSourceAddressOperand() = opFrom
-  or
   // Flow from an element to an array or union that contains it.
   instrTo.(ChiInstruction).getPartialOperand() = opFrom and
   not instrTo.isResultConflated() and

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking1/TaintTrackingImpl.qll

@@ -75,24 +75,26 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isSanitizer(DataFlow::Node node) { none() }
 
   final override predicate isBarrier(DataFlow::Node node) {
-    isSanitizer(node) or
+    this.isSanitizer(node) or
     defaultTaintSanitizer(node)
   }
 
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierIn(DataFlow::Node node) { isSanitizerIn(node) }
+  final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
   predicate isSanitizerOut(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierOut(DataFlow::Node node) { isSanitizerOut(node) }
+  final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) { isSanitizerGuard(guard) }
+  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
+  }
 
   /**
    * Holds if the additional taint propagation step from `node1` to `node2`
@@ -101,7 +103,7 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isAdditionalTaintStep(DataFlow::Node node1, DataFlow::Node node2) { none() }
 
   final override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
-    isAdditionalTaintStep(node1, node2) or
+    this.isAdditionalTaintStep(node1, node2) or
     defaultAdditionalTaintStep(node1, node2)
   }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking2/TaintTrackingImpl.qll

@@ -75,24 +75,26 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isSanitizer(DataFlow::Node node) { none() }
 
   final override predicate isBarrier(DataFlow::Node node) {
-    isSanitizer(node) or
+    this.isSanitizer(node) or
     defaultTaintSanitizer(node)
   }
 
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierIn(DataFlow::Node node) { isSanitizerIn(node) }
+  final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
   predicate isSanitizerOut(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierOut(DataFlow::Node node) { isSanitizerOut(node) }
+  final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) { isSanitizerGuard(guard) }
+  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
+  }
 
   /**
    * Holds if the additional taint propagation step from `node1` to `node2`
@@ -101,7 +103,7 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isAdditionalTaintStep(DataFlow::Node node1, DataFlow::Node node2) { none() }
 
   final override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
-    isAdditionalTaintStep(node1, node2) or
+    this.isAdditionalTaintStep(node1, node2) or
     defaultAdditionalTaintStep(node1, node2)
   }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking3/TaintTrackingImpl.qll

@@ -75,24 +75,26 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isSanitizer(DataFlow::Node node) { none() }
 
   final override predicate isBarrier(DataFlow::Node node) {
-    isSanitizer(node) or
+    this.isSanitizer(node) or
     defaultTaintSanitizer(node)
   }
 
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierIn(DataFlow::Node node) { isSanitizerIn(node) }
+  final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
   predicate isSanitizerOut(DataFlow::Node node) { none() }
 
-  final override predicate isBarrierOut(DataFlow::Node node) { isSanitizerOut(node) }
+  final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) { isSanitizerGuard(guard) }
+  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
+  }
 
   /**
    * Holds if the additional taint propagation step from `node1` to `node2`
@@ -101,7 +103,7 @@ abstract class Configuration extends DataFlow::Configuration {
   predicate isAdditionalTaintStep(DataFlow::Node node1, DataFlow::Node node2) { none() }
 
   final override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
-    isAdditionalTaintStep(node1, node2) or
+    this.isAdditionalTaintStep(node1, node2) or
     defaultAdditionalTaintStep(node1, node2)
   }
 

cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/IRBlock.qll

@@ -24,7 +24,7 @@ class IRBlockBase extends TIRBlock {
   final string toString() { result = getFirstInstruction(this).toString() }
 
   /** Gets the source location of the first non-`Phi` instruction in this block. */
-  final Language::Location getLocation() { result = getFirstInstruction().getLocation() }
+  final Language::Location getLocation() { result = this.getFirstInstruction().getLocation() }
 
   /**
    * INTERNAL: Do not use.
@@ -39,7 +39,7 @@ class IRBlockBase extends TIRBlock {
     ) and
     this =
       rank[result + 1](IRBlock funcBlock, int sortOverride, int sortKey1, int sortKey2 |
-        funcBlock.getEnclosingFunction() = getEnclosingFunction() and
+        funcBlock.getEnclosingFunction() = this.getEnclosingFunction() and
         funcBlock.getFirstInstruction().hasSortKeys(sortKey1, sortKey2) and
         // Ensure that the block containing `EnterFunction` always comes first.
         if funcBlock.getFirstInstruction() instanceof EnterFunctionInstruction
@@ -59,15 +59,15 @@ class IRBlockBase extends TIRBlock {
    * Get the `Phi` instructions that appear at the start of this block.
    */
   final PhiInstruction getAPhiInstruction() {
-    Construction::getPhiInstructionBlockStart(result) = getFirstInstruction()
+    Construction::getPhiInstructionBlockStart(result) = this.getFirstInstruction()
   }
 
   /**
    * Gets an instruction in this block. This includes `Phi` instructions.
    */
   final Instruction getAnInstruction() {
-    result = getInstruction(_) or
-    result = getAPhiInstruction()
+    result = this.getInstruction(_) or
+    result = this.getAPhiInstruction()
   }
 
   /**
@@ -78,7 +78,9 @@ class IRBlockBase extends TIRBlock {
   /**
    * Gets the last instruction in this block.
    */
-  final Instruction getLastInstruction() { result = getInstruction(getInstructionCount() - 1) }
+  final Instruction getLastInstruction() {
+    result = this.getInstruction(this.getInstructionCount() - 1)
+  }
 
   /**
    * Gets the number of non-`Phi` instructions in this block.
@@ -149,7 +151,7 @@ class IRBlock extends IRBlockBase {
    * Block `A` dominates block `B` if any control flow path from the entry block of the function to
    * block `B` must pass through block `A`. A block always dominates itself.
    */
-  final predicate dominates(IRBlock block) { strictlyDominates(block) or this = block }
+  final predicate dominates(IRBlock block) { this.strictlyDominates(block) or this = block }
 
   /**
    * Gets a block on the dominance frontier of this block.
@@ -159,8 +161,8 @@ class IRBlock extends IRBlockBase {
    */
   pragma[noinline]
   final IRBlock dominanceFrontier() {
-    dominates(result.getAPredecessor()) and
-    not strictlyDominates(result)
+    this.dominates(result.getAPredecessor()) and
+    not this.strictlyDominates(result)
   }
 
   /**
@@ -189,7 +191,7 @@ class IRBlock extends IRBlockBase {
    * Block `A` post-dominates block `B` if any control flow path from `B` to the exit block of the
    * function must pass through block `A`. A block always post-dominates itself.
    */
-  final predicate postDominates(IRBlock block) { strictlyPostDominates(block) or this = block }
+  final predicate postDominates(IRBlock block) { this.strictlyPostDominates(block) or this = block }
 
   /**
    * Gets a block on the post-dominance frontier of this block.
@@ -199,16 +201,16 @@ class IRBlock extends IRBlockBase {
    */
   pragma[noinline]
   final IRBlock postPominanceFrontier() {
-    postDominates(result.getASuccessor()) and
-    not strictlyPostDominates(result)
+    this.postDominates(result.getASuccessor()) and
+    not this.strictlyPostDominates(result)
   }
 
   /**
    * Holds if this block is reachable from the entry block of its function.
    */
   final predicate isReachableFromFunctionEntry() {
-    this = getEnclosingIRFunction().getEntryBlock() or
-    getAPredecessor().isReachableFromFunctionEntry()
+    this = this.getEnclosingIRFunction().getEntryBlock() or
+    this.getAPredecessor().isReachableFromFunctionEntry()
   }
 }