Merge branch 'main' of github.com:github/codeql into SharedDataflow_SequenceFlow

change-notes/1.26/analysis-cpp.md

@@ -0,0 +1,24 @@
+# Improvements to C/C++ analysis
+
+The following changes in version 1.26 affect C/C++ analysis in all applications.
+
+## General improvements
+
+## New queries
+
+| **Query**                   | **Tags**  | **Purpose**                                                        |
+|-----------------------------|-----------|--------------------------------------------------------------------|
+
+## Changes to existing queries
+
+| **Query**                  | **Expected impact**    | **Change**                                                       |
+|----------------------------|------------------------|------------------------------------------------------------------|
+| Inconsistent direction of for loop (`cpp/inconsistent-loop-direction`) | Fewer false positive results | The query now accounts for intentional wrapping of an unsigned loop counter. |
+| Overflow in uncontrolled allocation size (`cpp/uncontrolled-allocation-size`) | | The precision of this query has been decreased from "high" to "medium". As a result, the query is still run but results are no longer displayed on LGTM by default. |
+| Comparison result is always the same (`cpp/constant-comparison`) | More correct results | Bounds on expressions involving multiplication can now be determined in more cases. |
+
+## Changes to libraries
+
+* The models library now models more taint flows through `std::string`.
+* The `SimpleRangeAnalysis` library now supports multiplications of the form
+  `e1 * e2` when `e1` and `e2` are unsigned.

change-notes/1.26/analysis-csharp.md

@@ -0,0 +1,29 @@
+# Improvements to C# analysis
+
+The following changes in version 1.26 affect C# analysis in all applications.
+
+## New queries
+
+| **Query**                   | **Tags**  | **Purpose**                                                        |
+|-----------------------------|-----------|--------------------------------------------------------------------|
+
+
+## Changes to existing queries
+
+| **Query**                    | **Expected impact**    | **Change**                        |
+|------------------------------|------------------------|-----------------------------------|
+
+
+## Removal of old queries
+
+## Changes to code extraction
+
+* Partial method bodies are extracted. Previously, partial method bodies were skipped completely.
+
+## Changes to libraries
+
+## Changes to autobuilder
+
+## Changes to tooling support
+
+* The Abstract Syntax Tree of C# files can be printed in Visual Studio Code.

change-notes/1.26/analysis-javascript.md

@@ -0,0 +1,30 @@
+# Improvements to JavaScript analysis
+
+## General improvements
+
+* Support for the following frameworks and libraries has been improved:
+  - [fast-json-stable-stringify](https://www.npmjs.com/package/fast-json-stable-stringify)
+  - [fast-safe-stringify](https://www.npmjs.com/package/fast-safe-stringify)
+  - [javascript-stringify](https://www.npmjs.com/package/javascript-stringify)
+  - [js-stringify](https://www.npmjs.com/package/js-stringify)
+  - [json-stable-stringify](https://www.npmjs.com/package/json-stable-stringify)
+  - [json-stringify-safe](https://www.npmjs.com/package/json-stringify-safe)
+  - [json3](https://www.npmjs.com/package/json3)
+  - [object-inspect](https://www.npmjs.com/package/object-inspect)
+  - [pretty-format](https://www.npmjs.com/package/pretty-format)
+  - [stringify-object](https://www.npmjs.com/package/stringify-object)
+
+## New queries
+
+| **Query**                                                                       | **Tags**                                                          | **Purpose**                                                                                                                                                                            |
+|---------------------------------------------------------------------------------|-------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+
+
+## Changes to existing queries
+
+| **Query**                      | **Expected impact**          | **Change**                                                                |
+|--------------------------------|------------------------------|---------------------------------------------------------------------------|
+| Incomplete URL substring sanitization (`js/incomplete-url-substring-sanitization`) | More results | This query now recognizes additional URLs when the substring check is an inclusion check. |
+
+
+## Changes to libraries

cpp/ql/src/Likely Bugs/Likely Typos/inconsistentLoopDirection.ql

@@ -50,7 +50,12 @@ predicate illDefinedDecrForStmt(
     DataFlow::localFlowStep(DataFlow::exprNode(initialCondition), DataFlow::exprNode(lesserOperand)) and
     // `initialCondition` < `terminalCondition`
     (
-      upperBound(initialCondition) < lowerBound(terminalCondition)
+      upperBound(initialCondition) < lowerBound(terminalCondition) and
+      (
+        // exclude cases where the loop counter is `unsigned` (where wrapping behaviour can be used deliberately)
+        v.getUnspecifiedType().(IntegralType).isSigned() or
+        initialCondition.getValue().toInt() = 0
+      )
       or
       (forstmt.conditionAlwaysFalse() or forstmt.conditionAlwaysTrue())
     )

cpp/ql/src/Metrics/Files/FNumberOfTests.ql

@@ -18,6 +18,9 @@ Expr getTest() {
   or
   // boost tests; http://www.boost.org/
   result.(FunctionCall).getTarget().hasQualifiedName("boost::unit_test", "make_test_case")
+  or
+  // googletest tests; https://github.com/google/googletest/
+  result.(FunctionCall).getTarget().hasQualifiedName("testing::internal", "MakeAndRegisterTestInfo")
 }
 
 from File f, int n

cpp/ql/src/Microsoft/SAL.qll

@@ -1,5 +1,13 @@
+/**
+ * Provides classes for identifying and reasoning about Microsoft source code
+ * annotation language (SAL) macros.
+ */
+
 import cpp
 
+/**
+ * A SAL macro defined in `sal.h` or a similar header file.
+ */
 class SALMacro extends Macro {
   SALMacro() {
     exists(string filename | filename = this.getFile().getBaseName() |
@@ -20,27 +28,34 @@ class SALMacro extends Macro {
 }
 
 pragma[noinline]
-predicate isTopLevelMacroAccess(MacroAccess ma) { not exists(ma.getParentInvocation()) }
+private predicate isTopLevelMacroAccess(MacroAccess ma) { not exists(ma.getParentInvocation()) }
 
+/**
+ * An invocation of a SAL macro (excluding invocations inside other macros).
+ */
 class SALAnnotation extends MacroInvocation {
   SALAnnotation() {
     this.getMacro() instanceof SALMacro and
     isTopLevelMacroAccess(this)
   }
 
-  /** Returns the `Declaration` annotated by `this`. */
+  /** Gets the `Declaration` annotated by `this`. */
   Declaration getDeclaration() {
     annotatesAt(this, result.getADeclarationEntry(), _, _) and
     not result instanceof Type // exclude typedefs
   }
 
-  /** Returns the `DeclarationEntry` annotated by `this`. */
+  /** Gets the `DeclarationEntry` annotated by `this`. */
   DeclarationEntry getDeclarationEntry() {
     annotatesAt(this, result, _, _) and
     not result instanceof TypeDeclarationEntry // exclude typedefs
   }
 }
 
+/**
+ * A SAL macro indicating that the return value of a function should always be
+ * checked.
+ */
 class SALCheckReturn extends SALAnnotation {
   SALCheckReturn() {
     exists(SALMacro m | m = this.getMacro() |
@@ -50,6 +65,10 @@ class SALCheckReturn extends SALAnnotation {
   }
 }
 
+/**
+ * A SAL macro indicating that a pointer variable or return value should not be
+ * `NULL`.
+ */
 class SALNotNull extends SALAnnotation {
   SALNotNull() {
     exists(SALMacro m | m = this.getMacro() |
@@ -69,6 +88,9 @@ class SALNotNull extends SALAnnotation {
   }
 }
 
+/**
+ * A SAL macro indicating that a value may be `NULL`.
+ */
 class SALMaybeNull extends SALAnnotation {
   SALMaybeNull() {
     exists(SALMacro m | m = this.getMacro() |
@@ -79,13 +101,29 @@ class SALMaybeNull extends SALAnnotation {
   }
 }
 
+/**
+ * A parameter annotated by one or more SAL annotations.
+ */
+class SALParameter extends Parameter {
+  /** One of this parameter's annotations. */
+  SALAnnotation a;
+
+  SALParameter() { annotatesAt(a, this.getADeclarationEntry(), _, _) }
+
+  predicate isIn() { a.getMacroName().toLowerCase().matches("%\\_in%") }
+
+  predicate isOut() { a.getMacroName().toLowerCase().matches("%\\_out%") }
+
+  predicate isInOut() { a.getMacroName().toLowerCase().matches("%\\_inout%") }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Implementation details
 /**
  * Holds if `a` annotates the declaration entry `d` and
  * its start position is the `idx`th position in `file` that holds a SAL element.
  */
-predicate annotatesAt(SALAnnotation a, DeclarationEntry d, File file, int idx) {
+private predicate annotatesAt(SALAnnotation a, DeclarationEntry d, File file, int idx) {
   annotatesAtPosition(a.(SALElement).getStartPosition(), d, file, idx)
 }
 
@@ -109,22 +147,6 @@ private predicate annotatesAtPosition(SALPosition pos, DeclarationEntry d, File
   )
 }
 
-/**
- * A parameter annotated by one or more SAL annotations.
- */
-class SALParameter extends Parameter {
-  /** One of this parameter's annotations. */
-  SALAnnotation a;
-
-  SALParameter() { annotatesAt(a, this.getADeclarationEntry(), _, _) }
-
-  predicate isIn() { a.getMacroName().toLowerCase().matches("%\\_in%") }
-
-  predicate isOut() { a.getMacroName().toLowerCase().matches("%\\_out%") }
-
-  predicate isInOut() { a.getMacroName().toLowerCase().matches("%\\_inout%") }
-}
-
 /**
  * A SAL element, that is, a SAL annotation or a declaration entry
  * that may have SAL annotations.

cpp/ql/src/Security/CWE/CWE-190/TaintedAllocationSize.ql

@@ -4,7 +4,7 @@
  *              user can result in integer overflow.
  * @kind path-problem
  * @problem.severity error
- * @precision high
+ * @precision medium
  * @id cpp/uncontrolled-allocation-size
  * @tags reliability
  *       security

cpp/ql/src/experimental/Security/CWE/CWE-120/MemoryUnsafeFunctionScan.cpp

@@ -0,0 +1,25 @@
+///// Library routines /////
+
+int scanf(const char *format, ...);
+int sscanf(const char *str, const char *format, ...);
+int fscanf(const char *str, const char *format, ...);
+
+///// EXAMPLES /////
+
+int main(int argc, char **argv)
+{
+
+    // BAD, do not use scanf without specifying a length first
+    char buf1[10];
+    scanf("%s", buf1);
+
+    // GOOD, length is specified. The length should be one less than the size of the buffer, since the last character is the NULL terminator.
+    char buf2[10];
+    sscanf(buf2, "%9s");
+
+    // BAD, do not use scanf without specifying a length first
+    char file[10];
+    fscanf(file, "%s", buf2);
+
+    return 0;
+}

cpp/ql/src/experimental/Security/CWE/CWE-120/MemoryUnsafeFunctionScan.qhelp

@@ -0,0 +1,25 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<overview>
+<p>It is bad practice to use any of the <code>scanf</code> functions without including a specified length within the format parameter, as it will be vulnerable to buffer overflows.</p>
+
+</overview>
+
+<recommendation>
+
+<p>Specify a length within the format string parameter, and make this length one less than the size of the buffer, since the last character should be reserved for the NULL terminator.</p>
+
+</recommendation>
+
+<example>
+<p>The following example demonstrates safe and unsafe uses of <code>scanf</code> type functions.</p>
+<sample src="MemoryUnsafeFunctionScan.cpp" />
+
+</example>
+
+<references>
+</references>
+
+</qhelp>

cpp/ql/src/experimental/Security/CWE/CWE-120/MemoryUnsafeFunctionScan.ql

@@ -0,0 +1,19 @@
+/**
+ * @name Scanf function without a specified length
+ * @description Use of one of the scanf functions without a specified length.
+ * @kind problem
+ * @problem.severity warning
+ * @id cpp/memory-unsafe-function-scan
+ * @tags reliability
+ *       security
+ *       external/cwe/cwe-120
+ */
+
+import cpp
+import semmle.code.cpp.commons.Scanf
+
+from FunctionCall call, ScanfFunction sff
+where
+  call.getTarget() = sff and
+  call.getArgument(sff.getFormatParameterIndex()).getValue().regexpMatch(".*%l?s.*")
+select call, "Dangerous use of one of the scanf functions"

cpp/ql/src/experimental/Security/CWE/CWE-359/PrivateCleartextWrite.qhelp

@@ -0,0 +1,32 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<overview>
+<p>Private data that is stored in a file or buffer unencrypted is accessible to an attacker who gains access to the
+storage.</p>
+
+</overview>
+<recommendation>
+
+<p>Ensure that private data is always encrypted before being stored.
+It may be wise to encrypt information before it is put into a buffer that may be readable in memory.</p>
+
+<p>In general, decrypt private data only at the point where it is necessary for it to be used in
+cleartext.</p>
+
+</recommendation>
+
+<references>
+
+<li><a href="https://owasp.org/www-project-top-ten/OWASP_Top_Ten_2017/Top_10-2017_A3-Sensitive_Data_Exposure">OWASP Sensitive_Data_Exposure</a></li>
+<li>M. Dowd, J. McDonald and J. Schuhm, <i>The Art of Software Security Assessment</i>, 1st Edition, Chapter 2 - 'Common Vulnerabilities of Encryption', p. 43. Addison Wesley, 2006.</li> 
+<li>M. Howard and D. LeBlanc, <i>Writing Secure Code</i>, 2nd Edition, Chapter 9 - 'Protecting Secret Data', p. 299. Microsoft, 2002.</li>
+
+
+
+<!--  LocalWords:  CWE
+ -->
+
+</references>
+</qhelp>

cpp/ql/src/experimental/Security/CWE/CWE-359/PrivateCleartextWrite.ql

@@ -0,0 +1,21 @@
+/**
+ * @name Exposure of private information
+ * @description If private information is written to an external location, it may be accessible by
+ *              unauthorized persons.
+ * @kind path-problem
+ * @problem.severity error
+ * @id cpp/private-cleartext-write
+ * @tags security
+ *       external/cwe/cwe-359
+ */
+
+import cpp
+import experimental.semmle.code.cpp.security.PrivateCleartextWrite
+import experimental.semmle.code.cpp.security.PrivateCleartextWrite::PrivateCleartextWrite
+import DataFlow::PathGraph
+
+from WriteConfig b, DataFlow::PathNode source, DataFlow::PathNode sink
+where b.hasFlowPath(source, sink)
+select sink.getNode(),
+  "This write into the external location '" + sink + "' may contain unencrypted data from $@",
+  source, "this source."

cpp/ql/src/experimental/semmle/code/cpp/models/interfaces/SimpleRangeAnalysisExpr.qll

@@ -0,0 +1,78 @@
+/**
+ * EXPERIMENTAL: The API of this module may change without notice.
+ *
+ * Provides a class for modeling `Expr`s with a restricted range.
+ */
+
+import cpp
+import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
+
+/**
+ * EXPERIMENTAL: The API of this class may change without notice.
+ *
+ * An expression for which a range can be deduced. Extend this class to add
+ * functionality to the range analysis library.
+ */
+abstract class SimpleRangeAnalysisExpr extends Expr {
+  /**
+   * Gets the lower bound of the expression.
+   *
+   * Implementations of this predicate should use
+   * `getFullyConvertedLowerBounds` and `getFullyConvertedUpperBounds` for
+   * recursive calls to get the bounds of their children.
+   */
+  abstract float getLowerBounds();
+
+  /**
+   * Gets the upper bound of the expression.
+   *
+   * Implementations of this predicate should use
+   * `getFullyConvertedLowerBounds` and `getFullyConvertedUpperBounds` for
+   * recursive calls to get the bounds of their children.
+   */
+  abstract float getUpperBounds();
+
+  /**
+   * Holds if the range this expression depends on the definition `srcDef` for
+   * StackVariable `srcVar`.
+   *
+   * Because this predicate cannot be recursive, most implementations should
+   * override `dependsOnChild` instead.
+   */
+  predicate dependsOnDef(RangeSsaDefinition srcDef, StackVariable srcVar) { none() }
+
+  /**
+   * Holds if this expression depends on the range of its unconverted
+   * subexpression `child`. This information is used to inform the range
+   * analysis about cyclic dependencies. Without this information, range
+   * analysis might work for simple cases but will go into infinite loops on
+   * complex code.
+   *
+   * For example, when modeling a function call whose return value depends on
+   * all of its arguments, implement this predicate as
+   * `child = this.getAnArgument()`.
+   */
+  abstract predicate dependsOnChild(Expr child);
+}
+
+import SimpleRangeAnalysisInternal
+
+/**
+ * This class exists to prevent the QL front end from emitting compile errors
+ * inside `SimpleRangeAnalysis.qll` about certain conjuncts being empty
+ * because the overrides of `SimpleRangeAnalysisExpr` that happen to be in
+ * scope do not make use of every feature it offers.
+ */
+private class Empty extends SimpleRangeAnalysisExpr {
+  Empty() {
+    // This predicate is complicated enough that the QL type checker doesn't
+    // see it as empty but simple enough that the optimizer should.
+    this = this and none()
+  }
+
+  override float getLowerBounds() { none() }
+
+  override float getUpperBounds() { none() }
+
+  override predicate dependsOnChild(Expr child) { none() }
+}

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

@@ -0,0 +1,63 @@
+/**
+ * Provides a taint-tracking configuration for reasoning about private information flowing unencrypted to an external location.
+ */
+
+import cpp
+import semmle.code.cpp.dataflow.TaintTracking
+import experimental.semmle.code.cpp.security.PrivateData
+import semmle.code.cpp.security.FileWrite
+import semmle.code.cpp.security.BufferWrite
+import semmle.code.cpp.dataflow.TaintTracking
+
+module PrivateCleartextWrite {
+  /**
+   * A data flow source for private information flowing unencrypted to an external location.
+   */
+  abstract class Source extends DataFlow::ExprNode { }
+
+  /**
+   * A data flow sink for private information flowing unencrypted to an external location.
+   */
+  abstract class Sink extends DataFlow::ExprNode { }
+
+  /**
+   * A sanitizer for private information flowing unencrypted to an external location.
+   */
+  abstract class Sanitizer extends DataFlow::ExprNode { }
+
+  /** A call to any method whose name suggests that it encodes or encrypts the parameter. */
+  class ProtectSanitizer extends Sanitizer {
+    ProtectSanitizer() {
+      exists(Function m, string s |
+        this.getExpr().(FunctionCall).getTarget() = m and
+        m.getName().regexpMatch("(?i).*" + s + ".*")
+      |
+        s = "protect" or s = "encode" or s = "encrypt"
+      )
+    }
+  }
+
+  class WriteConfig extends TaintTracking::Configuration {
+    WriteConfig() { this = "Write configuration" }
+
+    override predicate isSource(DataFlow::Node source) { source instanceof Source }
+
+    override predicate isSink(DataFlow::Node sink) { sink instanceof Sink }
+
+    override predicate isSanitizer(DataFlow::Node node) { node instanceof Sanitizer }
+  }
+
+  class PrivateDataSource extends Source {
+    PrivateDataSource() { this.getExpr() instanceof PrivateDataExpr }
+  }
+
+  class WriteSink extends Sink {
+    WriteSink() {
+      exists(FileWrite f, BufferWrite b |
+        this.asExpr() = f.getASource()
+        or
+        this.asExpr() = b.getAChild()
+      )
+    }
+  }
+}

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

@@ -0,0 +1,53 @@
+/**
+ * Provides classes and predicates for identifying private data and functions for security.
+ *
+ * 'Private' data in general is anything that would compromise user privacy if exposed. This
+ * library tries to guess where private data may either be stored in a variable or produced by a
+ * function.
+ *
+ * This library is not concerned with credentials. See `SensitiveActions` for expressions related
+ * to credentials.
+ */
+
+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%"
+}
+
+/** An expression that might contain private data. */
+abstract class PrivateDataExpr extends Expr { }
+
+/** A functiond call that might produce private data. */
+class PrivateFunctionCall extends PrivateDataExpr, FunctionCall {
+  PrivateFunctionCall() {
+    exists(string s | this.getTarget().getName().toLowerCase() = s | s.matches(privateNames()))
+  }
+}
+
+/** An access to a variable that might contain private data. */
+class PrivateVariableAccess extends PrivateDataExpr, VariableAccess {
+  PrivateVariableAccess() {
+    exists(string s | this.getTarget().getName().toLowerCase() = s | s.matches(privateNames()))
+  }
+}

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

@@ -214,6 +214,9 @@ abstract class ImplicitConversionFunction extends MemberFunction {
 }
 
 /**
+ * DEPRECATED: as of C++11 this class does not correspond perfectly with the
+ * language definition of a converting constructor.
+ *
  * A C++ constructor that also defines an implicit conversion. For example the
  * function `MyClass` in the following code is a `ConversionConstructor`:
  * ```
@@ -225,15 +228,16 @@ abstract class ImplicitConversionFunction extends MemberFunction {
  * };
  * ```
  */
-class ConversionConstructor extends Constructor, ImplicitConversionFunction {
+deprecated class ConversionConstructor extends Constructor, ImplicitConversionFunction {
   ConversionConstructor() {
     strictcount(Parameter p | p = getAParameter() and not p.hasInitializer()) = 1 and
-    not hasSpecifier("explicit") and
-    not this instanceof CopyConstructor
+    not hasSpecifier("explicit")
   }
 
   override string getAPrimaryQlClass() {
-    not this instanceof MoveConstructor and result = "ConversionConstructor"
+    not this instanceof CopyConstructor and
+    not this instanceof MoveConstructor and
+    result = "ConversionConstructor"
   }
 
   /** Gets the type this `ConversionConstructor` takes as input. */

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

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

@@ -512,13 +512,19 @@ abstract class CallContext extends TCallContext {
   abstract predicate relevantFor(DataFlowCallable callable);
 }
 
-class CallContextAny extends CallContext, TAnyCallContext {
+abstract class CallContextNoCall extends CallContext { }
+
+class CallContextAny extends CallContextNoCall, TAnyCallContext {
   override string toString() { result = "CcAny" }
 
   override predicate relevantFor(DataFlowCallable callable) { any() }
 }
 
-abstract class CallContextCall extends CallContext { }
+abstract class CallContextCall extends CallContext {
+  /** Holds if this call context may be `call`. */
+  bindingset[call]
+  abstract predicate matchesCall(DataFlowCall call);
+}
 
 class CallContextSpecificCall extends CallContextCall, TSpecificCall {
   override string toString() {
@@ -529,6 +535,8 @@ class CallContextSpecificCall extends CallContextCall, TSpecificCall {
     recordDataFlowCallSite(getCall(), callable)
   }
 
+  override predicate matchesCall(DataFlowCall call) { call = this.getCall() }
+
   DataFlowCall getCall() { this = TSpecificCall(result) }
 }
 
@@ -538,9 +546,11 @@ class CallContextSomeCall extends CallContextCall, TSomeCall {
   override predicate relevantFor(DataFlowCallable callable) {
     exists(ParameterNode p | p.getEnclosingCallable() = callable)
   }
+
+  override predicate matchesCall(DataFlowCall call) { any() }
 }
 
-class CallContextReturn extends CallContext, TReturn {
+class CallContextReturn extends CallContextNoCall, TReturn {
   override string toString() {
     exists(DataFlowCall call | this = TReturn(_, call) | result = "CcReturn(" + call + ")")
   }

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/dataflow/internal/TaintTrackingUtil.qll

@@ -65,6 +65,15 @@ predicate localAdditionalTaintStep(DataFlow::Node nodeFrom, DataFlow::Node nodeT
     // tracking. The flow from expression `x` into `x++` etc. is handled in the
     // case above.
     exprTo = DataFlow::getAnAccessToAssignedVariable(exprFrom.(PostfixCrementOperation))
+    or
+    // In `for (char c : s) { ... c ... }`, this rule propagates taint from `s`
+    // to `c`.
+    exists(RangeBasedForStmt rbf |
+      exprFrom = rbf.getRange() and
+      // It's guaranteed up to at least C++20 that the range-based for loop
+      // desugars to a variable with an initializer.
+      exprTo = rbf.getVariable().getInitializer().getExpr()
+    )
   )
   or
   // Taint can flow through modeled functions

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

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

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

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

@@ -512,13 +512,19 @@ abstract class CallContext extends TCallContext {
   abstract predicate relevantFor(DataFlowCallable callable);
 }
 
-class CallContextAny extends CallContext, TAnyCallContext {
+abstract class CallContextNoCall extends CallContext { }
+
+class CallContextAny extends CallContextNoCall, TAnyCallContext {
   override string toString() { result = "CcAny" }
 
   override predicate relevantFor(DataFlowCallable callable) { any() }
 }
 
-abstract class CallContextCall extends CallContext { }
+abstract class CallContextCall extends CallContext {
+  /** Holds if this call context may be `call`. */
+  bindingset[call]
+  abstract predicate matchesCall(DataFlowCall call);
+}
 
 class CallContextSpecificCall extends CallContextCall, TSpecificCall {
   override string toString() {
@@ -529,6 +535,8 @@ class CallContextSpecificCall extends CallContextCall, TSpecificCall {
     recordDataFlowCallSite(getCall(), callable)
   }
 
+  override predicate matchesCall(DataFlowCall call) { call = this.getCall() }
+
   DataFlowCall getCall() { this = TSpecificCall(result) }
 }
 
@@ -538,9 +546,11 @@ class CallContextSomeCall extends CallContextCall, TSomeCall {
   override predicate relevantFor(DataFlowCallable callable) {
     exists(ParameterNode p | p.getEnclosingCallable() = callable)
   }
+
+  override predicate matchesCall(DataFlowCall call) { any() }
 }
 
-class CallContextReturn extends CallContext, TReturn {
+class CallContextReturn extends CallContextNoCall, TReturn {
   override string toString() {
     exists(DataFlowCall call | this = TReturn(_, call) | result = "CcReturn(" + call + ")")
   }

cpp/ql/src/semmle/code/cpp/models/implementations/MemberFunction.qll

@@ -7,9 +7,17 @@ import semmle.code.cpp.models.interfaces.DataFlow
 import semmle.code.cpp.models.interfaces.Taint
 
 /**
- * Model for C++ conversion constructors.
+ * Model for C++ conversion constructors. As of C++11 this does not correspond
+ * perfectly with the language definition of a converting constructor, however,
+ * it does correspond with the constructors we are confident taint should flow
+ * through.
  */
-class ConversionConstructorModel extends ConversionConstructor, TaintFunction {
+class ConversionConstructorModel extends Constructor, TaintFunction {
+  ConversionConstructorModel() {
+    strictcount(Parameter p | p = getAParameter() and not p.hasInitializer()) = 1 and
+    not hasSpecifier("explicit")
+  }
+
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     // taint flow from the first constructor argument to the returned object
     input.isParameter(0) and

cpp/ql/src/semmle/code/cpp/models/implementations/StdString.qll

@@ -1,5 +1,12 @@
 import semmle.code.cpp.models.interfaces.Taint
 
+/**
+ * The `std::basic_string` template class.
+ */
+class StdBasicString extends TemplateClass {
+  StdBasicString() { this.hasQualifiedName("std", "basic_string") }
+}
+
 /**
  * The standard function `std::string.c_str`.
  */
@@ -12,3 +19,51 @@ class StdStringCStr extends TaintFunction {
     output.isReturnValue()
   }
 }
+
+/**
+ * The `std::string` function `operator+`.
+ */
+class StdStringPlus extends TaintFunction {
+  StdStringPlus() {
+    this.hasQualifiedName("std", "operator+") and
+    this.getUnspecifiedType() = any(StdBasicString s).getAnInstantiation()
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // flow from parameters to return value
+    (
+      input.isParameterDeref(0) or
+      input.isParameterDeref(1)
+    ) and
+    output.isReturnValue()
+  }
+}
+
+/**
+ * The `std::string` functions `operator+=` and `append`.
+ */
+class StdStringAppend extends TaintFunction {
+  StdStringAppend() {
+    this.hasQualifiedName("std", "basic_string", "operator+=") or
+    this.hasQualifiedName("std", "basic_string", "append")
+  }
+
+  /**
+   * Gets the index of a parameter to this function that is a string (or
+   * character).
+   */
+  int getAStringParameter() {
+    getParameter(result).getType() instanceof PointerType or
+    getParameter(result).getType() instanceof ReferenceType or
+    getParameter(result).getType() = getDeclaringType().getTemplateArgument(0) // i.e. `std::basic_string::CharT`
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // flow from parameter to string itself (qualifier) and return value
+    input.isParameterDeref(getAStringParameter()) and
+    (
+      output.isQualifierObject() or
+      output.isReturnValueDeref()
+    )
+  }
+}

cpp/ql/src/semmle/code/cpp/rangeanalysis/SimpleRangeAnalysis.qll

@@ -44,6 +44,7 @@
 
 import cpp
 private import RangeAnalysisUtils
+private import experimental.semmle.code.cpp.models.interfaces.SimpleRangeAnalysisExpr
 import RangeSSA
 import SimpleRangeAnalysisCached
 private import NanAnalysis
@@ -156,6 +157,10 @@ float safeFloor(float v) {
   result = v
 }
 
+private class UnsignedMulExpr extends MulExpr {
+  UnsignedMulExpr() { this.getType().(IntegralType).isUnsigned() }
+}
+
 /** Set of expressions which we know how to analyze. */
 private predicate analyzableExpr(Expr e) {
   // The type of the expression must be arithmetic. We reuse the logic in
@@ -178,6 +183,8 @@ private predicate analyzableExpr(Expr e) {
     or
     e instanceof SubExpr
     or
+    e instanceof UnsignedMulExpr
+    or
     e instanceof AssignExpr
     or
     e instanceof AssignAddExpr
@@ -207,6 +214,9 @@ private predicate analyzableExpr(Expr e) {
     or
     // `>>` by a constant
     exists(e.(RShiftExpr).getRightOperand().getValue())
+    or
+    // A modeled expression for range analysis
+    e instanceof SimpleRangeAnalysisExpr
   )
 }
 
@@ -278,6 +288,10 @@ private predicate exprDependsOnDef(Expr e, RangeSsaDefinition srcDef, StackVaria
   or
   exists(SubExpr subExpr | e = subExpr | exprDependsOnDef(subExpr.getAnOperand(), srcDef, srcVar))
   or
+  exists(UnsignedMulExpr mulExpr | e = mulExpr |
+    exprDependsOnDef(mulExpr.getAnOperand(), srcDef, srcVar)
+  )
+  or
   exists(AssignExpr addExpr | e = addExpr | exprDependsOnDef(addExpr.getRValue(), srcDef, srcVar))
   or
   exists(AssignAddExpr addExpr | e = addExpr |
@@ -318,6 +332,16 @@ private predicate exprDependsOnDef(Expr e, RangeSsaDefinition srcDef, StackVaria
   )
   or
   e = srcDef.getAUse(srcVar)
+  or
+  // A modeled expression for range analysis
+  exists(SimpleRangeAnalysisExpr rae | rae = e |
+    rae.dependsOnDef(srcDef, srcVar)
+    or
+    exists(Expr child |
+      rae.dependsOnChild(child) and
+      exprDependsOnDef(child, srcDef, srcVar)
+    )
+  )
 }
 
 /**
@@ -381,9 +405,17 @@ private predicate assignmentDef(RangeSsaDefinition def, StackVariable v, Expr ex
   )
 }
 
-/** See comment above sourceDef. */
+/** See comment above assignmentDef. */
 private predicate analyzableDef(RangeSsaDefinition def, StackVariable v) {
-  assignmentDef(def, v, _) or defDependsOnDef(def, v, _, _)
+  assignmentDef(def, v, _)
+  or
+  analyzableExpr(def.(AssignOperation)) and
+  v = def.getAVariable()
+  or
+  analyzableExpr(def.(CrementOperation)) and
+  v = def.getAVariable()
+  or
+  phiDependsOnDef(def, v, _, _)
 }
 
 /**
@@ -435,13 +467,6 @@ private float addRoundingDownSmall(float x, float small) {
   if (x + small) - x > small then result = (x + small).nextDown() else result = (x + small)
 }
 
-/**
- * Gets the truncated lower bounds of the fully converted expression.
- */
-private float getFullyConvertedLowerBounds(Expr expr) {
-  result = getTruncatedLowerBounds(expr.getFullyConverted())
-}
-
 /**
  * Gets the lower bounds of the expression.
  *
@@ -488,13 +513,6 @@ private float getTruncatedLowerBounds(Expr expr) {
     result = exprMinVal(expr)
 }
 
-/**
- * Gets the truncated upper bounds of the fully converted expression.
- */
-private float getFullyConvertedUpperBounds(Expr expr) {
-  result = getTruncatedUpperBounds(expr.getFullyConverted())
-}
-
 /**
  * Gets the upper bounds of the expression.
  *
@@ -625,6 +643,13 @@ private float getLowerBoundsImpl(Expr expr) {
     result = addRoundingDown(xLow, -yHigh)
   )
   or
+  exists(UnsignedMulExpr mulExpr, float xLow, float yLow |
+    expr = mulExpr and
+    xLow = getFullyConvertedLowerBounds(mulExpr.getLeftOperand()) and
+    yLow = getFullyConvertedLowerBounds(mulExpr.getRightOperand()) and
+    result = xLow * yLow
+  )
+  or
   exists(AssignExpr assign |
     expr = assign and
     result = getFullyConvertedLowerBounds(assign.getRValue())
@@ -711,7 +736,9 @@ private float getLowerBoundsImpl(Expr expr) {
   or
   // Use SSA to get the lower bounds for a variable use.
   exists(RangeSsaDefinition def, StackVariable v | expr = def.getAUse(v) |
-    result = getDefLowerBounds(def, v)
+    result = getDefLowerBounds(def, v) and
+    // Not explicitly modeled by a SimpleRangeAnalysisExpr
+    not expr instanceof SimpleRangeAnalysisExpr
   )
   or
   // unsigned `&` (tighter bounds may exist)
@@ -727,6 +754,12 @@ private float getLowerBoundsImpl(Expr expr) {
     right = rsExpr.getRightOperand().getFullyConverted().getValue().toInt() and
     result = safeFloor(left / 2.pow(right))
   )
+  or
+  // A modeled expression for range analysis
+  exists(SimpleRangeAnalysisExpr rangeAnalysisExpr |
+    rangeAnalysisExpr = expr and
+    result = rangeAnalysisExpr.getLowerBounds()
+  )
 }
 
 /** Only to be called by `getTruncatedUpperBounds`. */
@@ -794,6 +827,13 @@ private float getUpperBoundsImpl(Expr expr) {
     result = addRoundingUp(xHigh, -yLow)
   )
   or
+  exists(UnsignedMulExpr mulExpr, float xHigh, float yHigh |
+    expr = mulExpr and
+    xHigh = getFullyConvertedUpperBounds(mulExpr.getLeftOperand()) and
+    yHigh = getFullyConvertedUpperBounds(mulExpr.getRightOperand()) and
+    result = xHigh * yHigh
+  )
+  or
   exists(AssignExpr assign |
     expr = assign and
     result = getFullyConvertedUpperBounds(assign.getRValue())
@@ -878,7 +918,9 @@ private float getUpperBoundsImpl(Expr expr) {
   or
   // Use SSA to get the upper bounds for a variable use.
   exists(RangeSsaDefinition def, StackVariable v | expr = def.getAUse(v) |
-    result = getDefUpperBounds(def, v)
+    result = getDefUpperBounds(def, v) and
+    // Not explicitly modeled by a SimpleRangeAnalysisExpr
+    not expr instanceof SimpleRangeAnalysisExpr
   )
   or
   // unsigned `&` (tighter bounds may exist)
@@ -896,6 +938,12 @@ private float getUpperBoundsImpl(Expr expr) {
     right = rsExpr.getRightOperand().getFullyConverted().getValue().toInt() and
     result = safeFloor(left / 2.pow(right))
   )
+  or
+  // A modeled expression for range analysis
+  exists(SimpleRangeAnalysisExpr rangeAnalysisExpr |
+    rangeAnalysisExpr = expr and
+    result = rangeAnalysisExpr.getUpperBounds()
+  )
 }
 
 /**
@@ -1480,3 +1528,25 @@ private module SimpleRangeAnalysisCached {
     convertedExprMightOverflowPositively(expr)
   }
 }
+
+/**
+ * INTERNAL: do not use. This module contains utilities for use in the
+ * experimental `SimpleRangeAnalysisExpr` module.
+ */
+module SimpleRangeAnalysisInternal {
+  /**
+   * Gets the truncated lower bounds of the fully converted expression.
+   */
+  float getFullyConvertedLowerBounds(Expr expr) {
+    result = getTruncatedLowerBounds(expr.getFullyConverted())
+  }
+
+  /**
+   * Gets the truncated upper bounds of the fully converted expression.
+   */
+  float getFullyConvertedUpperBounds(Expr expr) {
+    result = getTruncatedUpperBounds(expr.getFullyConverted())
+  }
+}
+
+private import SimpleRangeAnalysisInternal

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.c

@@ -0,0 +1,9 @@
+/// Adds its arguments (has custom modeling in QL)
+int custom_add_function(int a, int b);
+
+int test_extensibility_add(int x) {
+  if (x >= -10 && x <= 10) {
+    int result = custom_add_function(x, 100);
+    return result; // 90 .. 110
+  }
+}

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.expected

@@ -0,0 +1,4 @@
+| extensibility.c:5:7:5:7 | x | -2.147483648E9 | 2.147483647E9 |
+| extensibility.c:5:19:5:19 | x | -10.0 | 2.147483647E9 |
+| extensibility.c:6:38:6:38 | x | -10.0 | 10.0 |
+| extensibility.c:7:12:7:17 | result | 90.0 | 110.0 |

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.ql

@@ -0,0 +1,32 @@
+import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
+import experimental.semmle.code.cpp.models.interfaces.SimpleRangeAnalysisExpr
+
+class CustomAddFunctionCall extends SimpleRangeAnalysisExpr, FunctionCall {
+  CustomAddFunctionCall() { this.getTarget().hasGlobalName("custom_add_function") }
+
+  override float getLowerBounds() {
+    exists(float lower0, float lower1 |
+      lower0 = getFullyConvertedLowerBounds(this.getArgument(0)) and
+      lower1 = getFullyConvertedLowerBounds(this.getArgument(1)) and
+      // Note: this rounds toward 0, not -Inf as it should
+      result = lower0 + lower1
+    )
+  }
+
+  override float getUpperBounds() {
+    exists(float upper0, float upper1 |
+      upper0 = getFullyConvertedUpperBounds(this.getArgument(0)) and
+      upper1 = getFullyConvertedUpperBounds(this.getArgument(1)) and
+      // Note: this rounds toward 0, not Inf as it should
+      result = upper0 + upper1
+    )
+  }
+
+  override predicate dependsOnChild(Expr child) { child = this.getAnArgument() }
+}
+
+from VariableAccess expr, float lower, float upper
+where
+  lower = lowerBound(expr) and
+  upper = upperBound(expr)
+select expr, lower, upper

cpp/ql/test/experimental/query-tests/Security/CWE/CWE-359/semmle/tests/PrivateCleartextWrite.expected

@@ -0,0 +1,21 @@
+edges
+| test.cpp:77:16:77:22 | medical | test.cpp:78:24:78:27 | temp |
+| test.cpp:81:17:81:20 | call to func | test.cpp:82:24:82:28 | buff5 |
+| test.cpp:81:22:81:28 | medical | test.cpp:81:17:81:20 | call to func |
+nodes
+| test.cpp:57:9:57:18 | theZipcode | semmle.label | theZipcode |
+| test.cpp:74:24:74:30 | medical | semmle.label | medical |
+| test.cpp:77:16:77:22 | medical | semmle.label | medical |
+| test.cpp:78:24:78:27 | temp | semmle.label | temp |
+| test.cpp:81:17:81:20 | call to func | semmle.label | call to func |
+| test.cpp:81:22:81:28 | medical | semmle.label | medical |
+| test.cpp:82:24:82:28 | buff5 | semmle.label | buff5 |
+| test.cpp:96:37:96:46 | theZipcode | semmle.label | theZipcode |
+| test.cpp:99:42:99:51 | theZipcode | semmle.label | theZipcode |
+#select
+| test.cpp:57:9:57:18 | theZipcode | This write into the external location 'theZipcode' may contain unencrypted data from $@ | test.cpp:57:9:57:18 | theZipcode | this source. |
+| test.cpp:74:24:74:30 | medical | This write into the external location 'medical' may contain unencrypted data from $@ | test.cpp:74:24:74:30 | medical | this source. |
+| test.cpp:78:24:78:27 | temp | This write into the external location 'temp' may contain unencrypted data from $@ | test.cpp:77:16:77:22 | medical | this source. |
+| test.cpp:82:24:82:28 | buff5 | This write into the external location 'buff5' may contain unencrypted data from $@ | test.cpp:81:22:81:28 | medical | this source. |
+| test.cpp:96:37:96:46 | theZipcode | This write into the external location 'theZipcode' may contain unencrypted data from $@ | test.cpp:96:37:96:46 | theZipcode | this source. |
+| test.cpp:99:42:99:51 | theZipcode | This write into the external location 'theZipcode' may contain unencrypted data from $@ | test.cpp:99:42:99:51 | theZipcode | this source. |

cpp/ql/test/experimental/query-tests/Security/CWE/CWE-359/semmle/tests/PrivateCleartextWrite.qlref

@@ -0,0 +1 @@
+experimental/Security/CWE/CWE-359/PrivateCleartextWrite.ql

cpp/ql/test/experimental/query-tests/Security/CWE/CWE-359/semmle/tests/test.cpp

@@ -0,0 +1,105 @@
+#define FILE int
+#define wchar char
+#define size_t int
+typedef int streamsize;
+
+size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
+int fputs(const char *s, FILE *stream);
+int fputc(int c, FILE *stream);
+int fprintf(FILE *stream, const char *format, ...);
+int sprintf(char *s, const char *format, ...);
+size_t strlen(const char *s);
+
+namespace std
+{
+  template <class charT>
+  struct char_traits;
+
+  template <class charT, class traits = char_traits<charT>>
+  class basic_ostream /*: virtual public basic_ios<charT,traits> - not needed for this test */
+  {
+  public:
+    typedef charT char_type;
+    basic_ostream<charT, traits> &write(const char_type *s, streamsize n);
+  };
+
+  template <class charT, class traits = char_traits<charT>>
+  class basic_ofstream : public basic_ostream<charT, traits>
+  {
+  public:
+  };
+
+  template <class charT, class traits>
+  basic_ostream<charT, traits> &operator<<(basic_ostream<charT, traits> &, const charT *);
+
+  typedef basic_ostream<char> ostream;
+  typedef basic_ofstream<char> ofstream;
+}; // namespace std
+
+using namespace std;
+
+char *encrypt(char *buffer)
+{
+  return buffer;
+}
+char *func(char *buffer)
+{
+  return buffer;
+}
+
+// test for CleartextFileWrite
+void file()
+{
+  char *theZipcode = "cleartext zipcode!";
+  FILE *file;
+
+  // BAD: write zipcode to file in cleartext
+  fputs(theZipcode, file);
+
+  // GOOD: encrypt first
+  char *encrypted = encrypt(theZipcode);
+  fwrite(encrypted, sizeof(encrypted), 1, file);
+}
+
+// test for CleartextBufferWrite
+int main(int argc, char **argv)
+{
+  char *medical = "medical";
+  char *buff1;
+  char *buff2;
+  char *buff3;
+  char *buff4;
+
+  // BAD: write medical to buffer in cleartext
+  sprintf(buff1, "%s", medical);
+
+  // BAD: write medical to buffer in cleartext
+  char *temp = medical;
+  sprintf(buff2, "%s", temp);
+
+  // BAD: write medical to buffer in cleartext
+  char *buff5 = func(medical);
+  sprintf(buff3, "%s", buff5);
+
+  char *buff6 = encrypt(medical);
+  // GOOD: encrypt first
+  sprintf(buff4, "%s", buff6);
+}
+
+// test for CleartextFileWrite
+void stream()
+{
+  char *theZipcode = "cleartext zipcode!";
+  ofstream mystream;
+
+  // BAD: write zipcode to file in cleartext
+  mystream << "the zipcode is: " << theZipcode;
+
+  // BAD: write zipcode to file in cleartext
+  (mystream << "the zipcode is: ").write(theZipcode, strlen(theZipcode));
+
+  // GOOD: encrypt first
+  char *encrypted = encrypt(theZipcode);
+  mystream << "the zipcode is: " << encrypted;
+  (mystream << "the zipcode is: ").write(encrypted, strlen(encrypted));
+}

cpp/ql/test/experimental/query-tests/Security/CWE/semmle/tests/MemoryUnsafeFunctionScan.cpp

@@ -0,0 +1,25 @@
+///// Library routines /////
+
+int scanf(const char *format, ...);
+int sscanf(const char *str, const char *format, ...);
+int fscanf(const char *str, const char *format, ...);
+
+///// Test code /////
+
+int main(int argc, char **argv)
+{
+
+    // BAD, do not use scanf without specifying a length first
+    char buf1[10];
+    scanf("%s", buf1);
+
+    // GOOD, length is specified
+    char buf2[10];
+    sscanf(buf2, "%9s");
+
+    // BAD, do not use scanf without specifying a length first
+    char file[10];
+    fscanf(file, "%s", buf2);
+
+    return 0;
+}

cpp/ql/test/experimental/query-tests/Security/CWE/semmle/tests/MemoryUnsafeFunctionScan.expected

@@ -0,0 +1,2 @@
+| MemoryUnsafeFunctionScan.cpp:14:5:14:9 | call to scanf | Dangerous use of one of the scanf functions |
+| MemoryUnsafeFunctionScan.cpp:22:5:22:10 | call to fscanf | Dangerous use of one of the scanf functions |

cpp/ql/test/experimental/query-tests/Security/CWE/semmle/tests/MemoryUnsafeFunctionScan.qlref

@@ -0,0 +1 @@
+experimental/Security/CWE/CWE-120/MemoryUnsafeFunctionScan.ql

cpp/ql/test/library-tests/dataflow/taint-tests/localTaint.expected

@@ -308,99 +308,230 @@
 | movableclass.cpp:65:13:65:18 | call to source | movableclass.cpp:65:13:65:20 | call to MyMovableClass | TAINT |
 | movableclass.cpp:65:13:65:20 | call to MyMovableClass | movableclass.cpp:65:8:65:9 | ref arg s3 | TAINT |
 | movableclass.cpp:65:13:65:20 | call to MyMovableClass | movableclass.cpp:65:11:65:11 | call to operator= | TAINT |
-| stl.cpp:67:12:67:17 | call to source | stl.cpp:71:7:71:7 | a |  |
-| stl.cpp:68:16:68:20 | 123 | stl.cpp:68:16:68:21 | call to basic_string | TAINT |
-| stl.cpp:68:16:68:21 | call to basic_string | stl.cpp:72:7:72:7 | b |  |
-| stl.cpp:68:16:68:21 | call to basic_string | stl.cpp:74:7:74:7 | b |  |
-| stl.cpp:69:16:69:21 | call to source | stl.cpp:69:16:69:24 | call to basic_string | TAINT |
-| stl.cpp:69:16:69:24 | call to basic_string | stl.cpp:73:7:73:7 | c |  |
-| stl.cpp:69:16:69:24 | call to basic_string | stl.cpp:75:7:75:7 | c |  |
-| stl.cpp:74:7:74:7 | b | stl.cpp:74:9:74:13 | call to c_str | TAINT |
-| stl.cpp:75:7:75:7 | c | stl.cpp:75:9:75:13 | call to c_str | TAINT |
-| stl.cpp:80:20:80:22 | call to basic_stringstream | stl.cpp:83:2:83:4 | ss1 |  |
-| stl.cpp:80:20:80:22 | call to basic_stringstream | stl.cpp:89:7:89:9 | ss1 |  |
-| stl.cpp:80:20:80:22 | call to basic_stringstream | stl.cpp:94:7:94:9 | ss1 |  |
-| stl.cpp:80:25:80:27 | call to basic_stringstream | stl.cpp:84:2:84:4 | ss2 |  |
-| stl.cpp:80:25:80:27 | call to basic_stringstream | stl.cpp:90:7:90:9 | ss2 |  |
-| stl.cpp:80:25:80:27 | call to basic_stringstream | stl.cpp:95:7:95:9 | ss2 |  |
-| stl.cpp:80:30:80:32 | call to basic_stringstream | stl.cpp:85:2:85:4 | ss3 |  |
-| stl.cpp:80:30:80:32 | call to basic_stringstream | stl.cpp:91:7:91:9 | ss3 |  |
-| stl.cpp:80:30:80:32 | call to basic_stringstream | stl.cpp:96:7:96:9 | ss3 |  |
-| stl.cpp:80:35:80:37 | call to basic_stringstream | stl.cpp:86:2:86:4 | ss4 |  |
-| stl.cpp:80:35:80:37 | call to basic_stringstream | stl.cpp:92:7:92:9 | ss4 |  |
-| stl.cpp:80:35:80:37 | call to basic_stringstream | stl.cpp:97:7:97:9 | ss4 |  |
-| stl.cpp:80:40:80:42 | call to basic_stringstream | stl.cpp:87:2:87:4 | ss5 |  |
-| stl.cpp:80:40:80:42 | call to basic_stringstream | stl.cpp:93:7:93:9 | ss5 |  |
-| stl.cpp:80:40:80:42 | call to basic_stringstream | stl.cpp:98:7:98:9 | ss5 |  |
-| stl.cpp:81:16:81:21 | call to source | stl.cpp:81:16:81:24 | call to basic_string | TAINT |
-| stl.cpp:81:16:81:24 | call to basic_string | stl.cpp:87:9:87:9 | t |  |
-| stl.cpp:83:2:83:4 | ref arg ss1 | stl.cpp:89:7:89:9 | ss1 |  |
-| stl.cpp:83:2:83:4 | ref arg ss1 | stl.cpp:94:7:94:9 | ss1 |  |
-| stl.cpp:84:2:84:4 | ref arg ss2 | stl.cpp:90:7:90:9 | ss2 |  |
-| stl.cpp:84:2:84:4 | ref arg ss2 | stl.cpp:95:7:95:9 | ss2 |  |
-| stl.cpp:85:2:85:4 | ref arg ss3 | stl.cpp:91:7:91:9 | ss3 |  |
-| stl.cpp:85:2:85:4 | ref arg ss3 | stl.cpp:96:7:96:9 | ss3 |  |
-| stl.cpp:86:2:86:4 | ref arg ss4 | stl.cpp:92:7:92:9 | ss4 |  |
-| stl.cpp:86:2:86:4 | ref arg ss4 | stl.cpp:97:7:97:9 | ss4 |  |
-| stl.cpp:87:2:87:4 | ref arg ss5 | stl.cpp:93:7:93:9 | ss5 |  |
-| stl.cpp:87:2:87:4 | ref arg ss5 | stl.cpp:98:7:98:9 | ss5 |  |
-| stl.cpp:101:32:101:37 | source | stl.cpp:106:9:106:14 | source |  |
-| stl.cpp:103:20:103:22 | call to basic_stringstream | stl.cpp:105:2:105:4 | ss1 |  |
-| stl.cpp:103:20:103:22 | call to basic_stringstream | stl.cpp:108:7:108:9 | ss1 |  |
-| stl.cpp:103:20:103:22 | call to basic_stringstream | stl.cpp:110:7:110:9 | ss1 |  |
-| stl.cpp:103:25:103:27 | call to basic_stringstream | stl.cpp:106:2:106:4 | ss2 |  |
-| stl.cpp:103:25:103:27 | call to basic_stringstream | stl.cpp:109:7:109:9 | ss2 |  |
-| stl.cpp:103:25:103:27 | call to basic_stringstream | stl.cpp:111:7:111:9 | ss2 |  |
-| stl.cpp:105:2:105:4 | ref arg ss1 | stl.cpp:108:7:108:9 | ss1 |  |
-| stl.cpp:105:2:105:4 | ref arg ss1 | stl.cpp:110:7:110:9 | ss1 |  |
-| stl.cpp:106:2:106:4 | ref arg ss2 | stl.cpp:109:7:109:9 | ss2 |  |
-| stl.cpp:106:2:106:4 | ref arg ss2 | stl.cpp:111:7:111:9 | ss2 |  |
-| stl.cpp:124:16:124:28 | call to basic_string | stl.cpp:125:7:125:11 | path1 |  |
-| stl.cpp:124:17:124:26 | call to user_input | stl.cpp:124:16:124:28 | call to basic_string | TAINT |
-| stl.cpp:125:7:125:11 | path1 | stl.cpp:125:13:125:17 | call to c_str | TAINT |
-| stl.cpp:128:10:128:19 | call to user_input | stl.cpp:128:10:128:21 | call to basic_string | TAINT |
-| stl.cpp:128:10:128:21 | call to basic_string | stl.cpp:128:2:128:21 | ... = ... |  |
-| stl.cpp:128:10:128:21 | call to basic_string | stl.cpp:129:7:129:11 | path2 |  |
-| stl.cpp:129:7:129:11 | path2 | stl.cpp:129:13:129:17 | call to c_str | TAINT |
-| stl.cpp:131:15:131:24 | call to user_input | stl.cpp:131:15:131:27 | call to basic_string | TAINT |
-| stl.cpp:131:15:131:27 | call to basic_string | stl.cpp:132:7:132:11 | path3 |  |
-| stl.cpp:132:7:132:11 | path3 | stl.cpp:132:13:132:17 | call to c_str | TAINT |
-| stl.cpp:137:19:137:24 | call to source | stl.cpp:140:17:140:18 | cs |  |
-| stl.cpp:137:19:137:24 | call to source | stl.cpp:142:7:142:8 | cs |  |
-| stl.cpp:140:17:140:18 | cs | stl.cpp:140:17:140:19 | call to basic_string | TAINT |
-| stl.cpp:140:17:140:19 | call to basic_string | stl.cpp:143:7:143:8 | ss |  |
-| stl.cpp:148:19:148:24 | call to source | stl.cpp:151:17:151:18 | cs |  |
-| stl.cpp:151:17:151:18 | cs | stl.cpp:151:17:151:19 | call to basic_string | TAINT |
-| stl.cpp:151:17:151:19 | call to basic_string | stl.cpp:154:7:154:8 | ss |  |
-| stl.cpp:151:17:151:19 | call to basic_string | stl.cpp:157:7:157:8 | ss |  |
-| stl.cpp:154:7:154:8 | ss | stl.cpp:154:10:154:14 | call to c_str | TAINT |
-| stl.cpp:154:10:154:14 | call to c_str | stl.cpp:154:2:154:16 | ... = ... |  |
-| stl.cpp:154:10:154:14 | call to c_str | stl.cpp:156:7:156:8 | cs |  |
-| stl.cpp:163:18:163:24 | hello | stl.cpp:163:18:163:25 | call to basic_string | TAINT |
-| stl.cpp:163:18:163:25 | call to basic_string | stl.cpp:168:8:168:9 | s1 |  |
-| stl.cpp:164:19:164:26 | call to basic_string | stl.cpp:169:8:169:9 | s2 |  |
-| stl.cpp:164:20:164:26 | hello | stl.cpp:164:19:164:26 | call to basic_string | TAINT |
-| stl.cpp:166:8:166:14 | call to basic_string | stl.cpp:166:3:166:14 | ... = ... |  |
-| stl.cpp:166:8:166:14 | call to basic_string | stl.cpp:170:8:170:9 | s3 |  |
-| stl.cpp:166:8:166:14 | hello | stl.cpp:166:8:166:14 | call to basic_string | TAINT |
-| stl.cpp:174:18:174:23 | call to source | stl.cpp:174:18:174:26 | call to basic_string | TAINT |
-| stl.cpp:174:18:174:26 | call to basic_string | stl.cpp:179:8:179:9 | s1 |  |
-| stl.cpp:175:19:175:27 | call to basic_string | stl.cpp:180:8:180:9 | s2 |  |
-| stl.cpp:175:20:175:25 | call to source | stl.cpp:175:19:175:27 | call to basic_string | TAINT |
-| stl.cpp:177:8:177:13 | call to source | stl.cpp:177:8:177:15 | call to basic_string | TAINT |
-| stl.cpp:177:8:177:15 | call to basic_string | stl.cpp:177:3:177:15 | ... = ... |  |
-| stl.cpp:177:8:177:15 | call to basic_string | stl.cpp:181:8:181:9 | s3 |  |
-| stl.cpp:185:15:185:16 | call to basic_string | stl.cpp:186:20:186:21 | s1 |  |
-| stl.cpp:185:15:185:16 | call to basic_string | stl.cpp:188:8:188:9 | s1 |  |
-| stl.cpp:185:15:185:16 | call to basic_string | stl.cpp:190:8:190:9 | s1 |  |
-| stl.cpp:186:20:186:21 | s1 | stl.cpp:191:8:191:9 | s2 |  |
-| stl.cpp:188:8:188:9 | s1 | stl.cpp:188:3:188:9 | ... = ... |  |
-| stl.cpp:188:8:188:9 | s1 | stl.cpp:192:8:192:9 | s3 |  |
-| stl.cpp:196:19:196:40 | call to basic_string | stl.cpp:200:8:200:9 | s1 |  |
-| stl.cpp:196:32:196:37 | call to source | stl.cpp:196:19:196:40 | call to basic_string | TAINT |
-| stl.cpp:198:8:198:28 | call to basic_string | stl.cpp:198:3:198:28 | ... = ... |  |
-| stl.cpp:198:8:198:28 | call to basic_string | stl.cpp:201:8:201:9 | s2 |  |
-| stl.cpp:198:20:198:25 | call to source | stl.cpp:198:8:198:28 | call to basic_string | TAINT |
+| string.cpp:24:12:24:17 | call to source | string.cpp:28:7:28:7 | a |  |
+| string.cpp:25:16:25:20 | 123 | string.cpp:25:16:25:21 | call to basic_string | TAINT |
+| string.cpp:25:16:25:21 | call to basic_string | string.cpp:29:7:29:7 | b |  |
+| string.cpp:25:16:25:21 | call to basic_string | string.cpp:31:7:31:7 | b |  |
+| string.cpp:26:16:26:21 | call to source | string.cpp:26:16:26:24 | call to basic_string | TAINT |
+| string.cpp:26:16:26:24 | call to basic_string | string.cpp:30:7:30:7 | c |  |
+| string.cpp:26:16:26:24 | call to basic_string | string.cpp:32:7:32:7 | c |  |
+| string.cpp:31:7:31:7 | b | string.cpp:31:9:31:13 | call to c_str | TAINT |
+| string.cpp:32:7:32:7 | c | string.cpp:32:9:32:13 | call to c_str | TAINT |
+| string.cpp:37:16:37:28 | call to basic_string | string.cpp:38:7:38:11 | path1 |  |
+| string.cpp:37:17:37:26 | call to user_input | string.cpp:37:16:37:28 | call to basic_string | TAINT |
+| string.cpp:38:7:38:11 | path1 | string.cpp:38:13:38:17 | call to c_str | TAINT |
+| string.cpp:41:10:41:19 | call to user_input | string.cpp:41:10:41:21 | call to basic_string | TAINT |
+| string.cpp:41:10:41:21 | call to basic_string | string.cpp:41:2:41:21 | ... = ... |  |
+| string.cpp:41:10:41:21 | call to basic_string | string.cpp:42:7:42:11 | path2 |  |
+| string.cpp:42:7:42:11 | path2 | string.cpp:42:13:42:17 | call to c_str | TAINT |
+| string.cpp:44:15:44:24 | call to user_input | string.cpp:44:15:44:27 | call to basic_string | TAINT |
+| string.cpp:44:15:44:27 | call to basic_string | string.cpp:45:7:45:11 | path3 |  |
+| string.cpp:45:7:45:11 | path3 | string.cpp:45:13:45:17 | call to c_str | TAINT |
+| string.cpp:50:19:50:24 | call to source | string.cpp:53:17:53:18 | cs |  |
+| string.cpp:50:19:50:24 | call to source | string.cpp:55:7:55:8 | cs |  |
+| string.cpp:53:17:53:18 | cs | string.cpp:53:17:53:19 | call to basic_string | TAINT |
+| string.cpp:53:17:53:19 | call to basic_string | string.cpp:56:7:56:8 | ss |  |
+| string.cpp:61:19:61:24 | call to source | string.cpp:64:17:64:18 | cs |  |
+| string.cpp:64:17:64:18 | cs | string.cpp:64:17:64:19 | call to basic_string | TAINT |
+| string.cpp:64:17:64:19 | call to basic_string | string.cpp:67:7:67:8 | ss |  |
+| string.cpp:64:17:64:19 | call to basic_string | string.cpp:70:7:70:8 | ss |  |
+| string.cpp:67:7:67:8 | ss | string.cpp:67:10:67:14 | call to c_str | TAINT |
+| string.cpp:67:10:67:14 | call to c_str | string.cpp:67:2:67:16 | ... = ... |  |
+| string.cpp:67:10:67:14 | call to c_str | string.cpp:69:7:69:8 | cs |  |
+| string.cpp:76:18:76:24 | hello | string.cpp:76:18:76:25 | call to basic_string | TAINT |
+| string.cpp:76:18:76:25 | call to basic_string | string.cpp:81:8:81:9 | s1 |  |
+| string.cpp:77:19:77:26 | call to basic_string | string.cpp:82:8:82:9 | s2 |  |
+| string.cpp:77:20:77:26 | hello | string.cpp:77:19:77:26 | call to basic_string | TAINT |
+| string.cpp:79:8:79:14 | call to basic_string | string.cpp:79:3:79:14 | ... = ... |  |
+| string.cpp:79:8:79:14 | call to basic_string | string.cpp:83:8:83:9 | s3 |  |
+| string.cpp:79:8:79:14 | hello | string.cpp:79:8:79:14 | call to basic_string | TAINT |
+| string.cpp:87:18:87:23 | call to source | string.cpp:87:18:87:26 | call to basic_string | TAINT |
+| string.cpp:87:18:87:26 | call to basic_string | string.cpp:92:8:92:9 | s1 |  |
+| string.cpp:88:19:88:27 | call to basic_string | string.cpp:93:8:93:9 | s2 |  |
+| string.cpp:88:20:88:25 | call to source | string.cpp:88:19:88:27 | call to basic_string | TAINT |
+| string.cpp:90:8:90:13 | call to source | string.cpp:90:8:90:15 | call to basic_string | TAINT |
+| string.cpp:90:8:90:15 | call to basic_string | string.cpp:90:3:90:15 | ... = ... |  |
+| string.cpp:90:8:90:15 | call to basic_string | string.cpp:94:8:94:9 | s3 |  |
+| string.cpp:98:15:98:16 | call to basic_string | string.cpp:99:20:99:21 | s1 |  |
+| string.cpp:98:15:98:16 | call to basic_string | string.cpp:101:8:101:9 | s1 |  |
+| string.cpp:98:15:98:16 | call to basic_string | string.cpp:103:8:103:9 | s1 |  |
+| string.cpp:99:20:99:21 | s1 | string.cpp:104:8:104:9 | s2 |  |
+| string.cpp:101:8:101:9 | s1 | string.cpp:101:3:101:9 | ... = ... |  |
+| string.cpp:101:8:101:9 | s1 | string.cpp:105:8:105:9 | s3 |  |
+| string.cpp:109:19:109:40 | call to basic_string | string.cpp:113:8:113:9 | s1 |  |
+| string.cpp:109:32:109:37 | call to source | string.cpp:109:19:109:40 | call to basic_string | TAINT |
+| string.cpp:111:8:111:28 | call to basic_string | string.cpp:111:3:111:28 | ... = ... |  |
+| string.cpp:111:8:111:28 | call to basic_string | string.cpp:114:8:114:9 | s2 |  |
+| string.cpp:111:20:111:25 | call to source | string.cpp:111:8:111:28 | call to basic_string | TAINT |
+| string.cpp:119:16:119:21 | call to source | string.cpp:119:16:119:24 | call to basic_string | TAINT |
+| string.cpp:119:16:119:24 | call to basic_string | string.cpp:120:15:120:15 | s |  |
+| string.cpp:119:16:119:24 | call to basic_string | string.cpp:124:33:124:33 | s |  |
+| string.cpp:119:16:119:24 | call to basic_string | string.cpp:124:50:124:50 | s |  |
+| string.cpp:119:16:119:24 | call to basic_string | string.cpp:128:16:128:16 | s |  |
+| string.cpp:120:15:120:15 | call to begin | string.cpp:120:15:120:15 | (__begin) |  |
+| string.cpp:120:15:120:15 | call to begin | string.cpp:120:15:120:15 | (__begin) |  |
+| string.cpp:120:15:120:15 | call to begin | string.cpp:120:15:120:15 | (__begin) |  |
+| string.cpp:120:15:120:15 | call to end | string.cpp:120:15:120:15 | (__end) |  |
+| string.cpp:120:15:120:15 | call to operator* | string.cpp:121:8:121:8 | c |  |
+| string.cpp:120:15:120:15 | ref arg (__begin) | string.cpp:120:15:120:15 | (__begin) |  |
+| string.cpp:120:15:120:15 | ref arg (__begin) | string.cpp:120:15:120:15 | (__begin) |  |
+| string.cpp:120:15:120:15 | ref arg (__begin) | string.cpp:120:15:120:15 | (__begin) |  |
+| string.cpp:120:15:120:15 | ref arg (__range) | string.cpp:120:15:120:15 | (__range) |  |
+| string.cpp:120:15:120:15 | s | string.cpp:120:15:120:15 | (__range) |  |
+| string.cpp:120:15:120:15 | s | string.cpp:120:15:120:15 | (__range) |  |
+| string.cpp:120:15:120:15 | s | string.cpp:120:15:120:15 | call to operator* | TAINT |
+| string.cpp:124:33:124:33 | ref arg s | string.cpp:124:50:124:50 | s |  |
+| string.cpp:124:33:124:33 | ref arg s | string.cpp:128:16:128:16 | s |  |
+| string.cpp:124:35:124:39 | call to begin | string.cpp:124:44:124:45 | it |  |
+| string.cpp:124:35:124:39 | call to begin | string.cpp:124:61:124:62 | it |  |
+| string.cpp:124:35:124:39 | call to begin | string.cpp:125:9:125:10 | it |  |
+| string.cpp:124:50:124:50 | ref arg s | string.cpp:124:50:124:50 | s |  |
+| string.cpp:124:50:124:50 | ref arg s | string.cpp:128:16:128:16 | s |  |
+| string.cpp:124:61:124:62 | ref arg it | string.cpp:124:44:124:45 | it |  |
+| string.cpp:124:61:124:62 | ref arg it | string.cpp:124:61:124:62 | it |  |
+| string.cpp:124:61:124:62 | ref arg it | string.cpp:125:9:125:10 | it |  |
+| string.cpp:128:16:128:16 | call to begin | string.cpp:128:16:128:16 | (__begin) |  |
+| string.cpp:128:16:128:16 | call to begin | string.cpp:128:16:128:16 | (__begin) |  |
+| string.cpp:128:16:128:16 | call to begin | string.cpp:128:16:128:16 | (__begin) |  |
+| string.cpp:128:16:128:16 | call to end | string.cpp:128:16:128:16 | (__end) |  |
+| string.cpp:128:16:128:16 | call to operator* | string.cpp:129:8:129:8 | c |  |
+| string.cpp:128:16:128:16 | ref arg (__begin) | string.cpp:128:16:128:16 | (__begin) |  |
+| string.cpp:128:16:128:16 | ref arg (__begin) | string.cpp:128:16:128:16 | (__begin) |  |
+| string.cpp:128:16:128:16 | ref arg (__begin) | string.cpp:128:16:128:16 | (__begin) |  |
+| string.cpp:128:16:128:16 | ref arg (__range) | string.cpp:128:16:128:16 | (__range) |  |
+| string.cpp:128:16:128:16 | s | string.cpp:128:16:128:16 | (__range) |  |
+| string.cpp:128:16:128:16 | s | string.cpp:128:16:128:16 | (__range) |  |
+| string.cpp:128:16:128:16 | s | string.cpp:128:16:128:16 | call to operator* | TAINT |
+| string.cpp:132:28:132:33 | call to source | string.cpp:132:28:132:36 | call to basic_string | TAINT |
+| string.cpp:132:28:132:36 | call to basic_string | string.cpp:133:22:133:28 | const_s |  |
+| string.cpp:133:22:133:22 | call to begin | string.cpp:133:22:133:22 | (__begin) |  |
+| string.cpp:133:22:133:22 | call to begin | string.cpp:133:22:133:22 | (__begin) |  |
+| string.cpp:133:22:133:22 | call to begin | string.cpp:133:22:133:22 | (__begin) |  |
+| string.cpp:133:22:133:22 | call to end | string.cpp:133:22:133:22 | (__end) |  |
+| string.cpp:133:22:133:22 | call to operator* | string.cpp:134:8:134:8 | c |  |
+| string.cpp:133:22:133:22 | ref arg (__begin) | string.cpp:133:22:133:22 | (__begin) |  |
+| string.cpp:133:22:133:22 | ref arg (__begin) | string.cpp:133:22:133:22 | (__begin) |  |
+| string.cpp:133:22:133:22 | ref arg (__begin) | string.cpp:133:22:133:22 | (__begin) |  |
+| string.cpp:133:22:133:28 | const_s | string.cpp:133:22:133:22 | (__range) |  |
+| string.cpp:133:22:133:28 | const_s | string.cpp:133:22:133:22 | (__range) |  |
+| string.cpp:133:22:133:28 | const_s | string.cpp:133:22:133:22 | call to operator* | TAINT |
+| string.cpp:140:18:140:24 | hello | string.cpp:140:18:140:25 | call to basic_string | TAINT |
+| string.cpp:140:18:140:25 | call to basic_string | string.cpp:143:8:143:9 | s1 |  |
+| string.cpp:140:18:140:25 | call to basic_string | string.cpp:143:13:143:14 | s1 |  |
+| string.cpp:140:18:140:25 | call to basic_string | string.cpp:144:8:144:9 | s1 |  |
+| string.cpp:140:18:140:25 | call to basic_string | string.cpp:145:13:145:14 | s1 |  |
+| string.cpp:140:18:140:25 | call to basic_string | string.cpp:148:8:148:9 | s1 |  |
+| string.cpp:140:18:140:25 | call to basic_string | string.cpp:149:8:149:9 | s1 |  |
+| string.cpp:141:18:141:23 | call to source | string.cpp:141:18:141:26 | call to basic_string | TAINT |
+| string.cpp:141:18:141:26 | call to basic_string | string.cpp:144:13:144:14 | s2 |  |
+| string.cpp:141:18:141:26 | call to basic_string | string.cpp:145:8:145:9 | s2 |  |
+| string.cpp:141:18:141:26 | call to basic_string | string.cpp:146:8:146:9 | s2 |  |
+| string.cpp:141:18:141:26 | call to basic_string | string.cpp:146:13:146:14 | s2 |  |
+| string.cpp:143:8:143:9 | s1 | string.cpp:143:11:143:11 | call to operator+ | TAINT |
+| string.cpp:143:13:143:14 | s1 | string.cpp:143:11:143:11 | call to operator+ | TAINT |
+| string.cpp:144:8:144:9 | s1 | string.cpp:144:11:144:11 | call to operator+ | TAINT |
+| string.cpp:144:13:144:14 | s2 | string.cpp:144:11:144:11 | call to operator+ | TAINT |
+| string.cpp:145:8:145:9 | s2 | string.cpp:145:11:145:11 | call to operator+ | TAINT |
+| string.cpp:145:13:145:14 | s1 | string.cpp:145:11:145:11 | call to operator+ | TAINT |
+| string.cpp:146:8:146:9 | s2 | string.cpp:146:11:146:11 | call to operator+ | TAINT |
+| string.cpp:146:13:146:14 | s2 | string.cpp:146:11:146:11 | call to operator+ | TAINT |
+| string.cpp:148:8:148:9 | s1 | string.cpp:148:11:148:11 | call to operator+ | TAINT |
+| string.cpp:148:13:148:20 |  world | string.cpp:148:11:148:11 | call to operator+ | TAINT |
+| string.cpp:149:8:149:9 | s1 | string.cpp:149:11:149:11 | call to operator+ | TAINT |
+| string.cpp:149:13:149:18 | call to source | string.cpp:149:11:149:11 | call to operator+ | TAINT |
+| string.cpp:153:18:153:22 | abc | string.cpp:153:18:153:23 | call to basic_string | TAINT |
+| string.cpp:153:18:153:23 | call to basic_string | string.cpp:157:8:157:9 | s3 |  |
+| string.cpp:153:18:153:23 | call to basic_string | string.cpp:160:8:160:9 | s3 |  |
+| string.cpp:153:18:153:23 | call to basic_string | string.cpp:164:8:164:9 | s3 |  |
+| string.cpp:153:18:153:23 | call to basic_string | string.cpp:169:8:169:9 | s3 |  |
+| string.cpp:153:18:153:23 | call to basic_string | string.cpp:173:8:173:9 | s3 |  |
+| string.cpp:154:18:154:23 | call to source | string.cpp:154:18:154:26 | call to basic_string | TAINT |
+| string.cpp:154:18:154:26 | call to basic_string | string.cpp:157:13:157:14 | s4 |  |
+| string.cpp:154:18:154:26 | call to basic_string | string.cpp:161:9:161:10 | s4 |  |
+| string.cpp:154:18:154:26 | call to basic_string | string.cpp:170:13:170:14 | s4 |  |
+| string.cpp:157:8:157:9 | s3 | string.cpp:157:11:157:11 | call to operator+ | TAINT |
+| string.cpp:157:11:157:11 | call to operator+ | string.cpp:157:3:157:14 | ... = ... |  |
+| string.cpp:157:11:157:11 | call to operator+ | string.cpp:158:8:158:9 | s5 |  |
+| string.cpp:157:13:157:14 | s4 | string.cpp:157:11:157:11 | call to operator+ | TAINT |
+| string.cpp:160:8:160:9 | s3 | string.cpp:160:3:160:9 | ... = ... |  |
+| string.cpp:160:8:160:9 | s3 | string.cpp:161:3:161:4 | s6 |  |
+| string.cpp:160:8:160:9 | s3 | string.cpp:162:8:162:9 | s6 |  |
+| string.cpp:161:3:161:4 | ref arg s6 | string.cpp:162:8:162:9 | s6 |  |
+| string.cpp:161:9:161:10 | s4 | string.cpp:161:3:161:4 | ref arg s6 | TAINT |
+| string.cpp:161:9:161:10 | s4 | string.cpp:161:6:161:6 | call to operator+= | TAINT |
+| string.cpp:164:8:164:9 | s3 | string.cpp:164:3:164:9 | ... = ... |  |
+| string.cpp:164:8:164:9 | s3 | string.cpp:165:3:165:4 | s7 |  |
+| string.cpp:164:8:164:9 | s3 | string.cpp:166:3:166:4 | s7 |  |
+| string.cpp:164:8:164:9 | s3 | string.cpp:167:8:167:9 | s7 |  |
+| string.cpp:165:3:165:4 | ref arg s7 | string.cpp:166:3:166:4 | s7 |  |
+| string.cpp:165:3:165:4 | ref arg s7 | string.cpp:167:8:167:9 | s7 |  |
+| string.cpp:165:9:165:14 | call to source | string.cpp:165:3:165:4 | ref arg s7 | TAINT |
+| string.cpp:165:9:165:14 | call to source | string.cpp:165:6:165:6 | call to operator+= | TAINT |
+| string.cpp:166:3:166:4 | ref arg s7 | string.cpp:167:8:167:9 | s7 |  |
+| string.cpp:166:9:166:11 |   | string.cpp:166:3:166:4 | ref arg s7 | TAINT |
+| string.cpp:166:9:166:11 |   | string.cpp:166:6:166:6 | call to operator+= | TAINT |
+| string.cpp:169:8:169:9 | s3 | string.cpp:169:3:169:9 | ... = ... |  |
+| string.cpp:169:8:169:9 | s3 | string.cpp:170:3:170:4 | s8 |  |
+| string.cpp:169:8:169:9 | s3 | string.cpp:171:8:171:9 | s8 |  |
+| string.cpp:170:3:170:4 | ref arg s8 | string.cpp:171:8:171:9 | s8 |  |
+| string.cpp:170:13:170:14 | s4 | string.cpp:170:3:170:4 | ref arg s8 | TAINT |
+| string.cpp:170:13:170:14 | s4 | string.cpp:170:6:170:11 | call to append | TAINT |
+| string.cpp:173:8:173:9 | s3 | string.cpp:173:3:173:9 | ... = ... |  |
+| string.cpp:173:8:173:9 | s3 | string.cpp:174:3:174:4 | s9 |  |
+| string.cpp:173:8:173:9 | s3 | string.cpp:175:3:175:4 | s9 |  |
+| string.cpp:173:8:173:9 | s3 | string.cpp:176:8:176:9 | s9 |  |
+| string.cpp:174:3:174:4 | ref arg s9 | string.cpp:175:3:175:4 | s9 |  |
+| string.cpp:174:3:174:4 | ref arg s9 | string.cpp:176:8:176:9 | s9 |  |
+| string.cpp:174:13:174:18 | call to source | string.cpp:174:3:174:4 | ref arg s9 | TAINT |
+| string.cpp:174:13:174:18 | call to source | string.cpp:174:6:174:11 | call to append | TAINT |
+| string.cpp:175:3:175:4 | ref arg s9 | string.cpp:176:8:176:9 | s9 |  |
+| string.cpp:175:13:175:15 |   | string.cpp:175:3:175:4 | ref arg s9 | TAINT |
+| string.cpp:175:13:175:15 |   | string.cpp:175:6:175:11 | call to append | TAINT |
+| string.cpp:180:19:180:23 | abc | string.cpp:180:19:180:24 | call to basic_string | TAINT |
+| string.cpp:180:19:180:24 | call to basic_string | string.cpp:183:3:183:5 | s10 |  |
+| string.cpp:180:19:180:24 | call to basic_string | string.cpp:184:8:184:10 | s10 |  |
+| string.cpp:181:12:181:26 | call to source | string.cpp:183:17:183:17 | c |  |
+| string.cpp:183:3:183:5 | ref arg s10 | string.cpp:184:8:184:10 | s10 |  |
+| string.cpp:183:17:183:17 | c | string.cpp:183:3:183:5 | ref arg s10 | TAINT |
+| string.cpp:183:17:183:17 | c | string.cpp:183:7:183:12 | call to append | TAINT |
+| stringstream.cpp:13:20:13:22 | call to basic_stringstream | stringstream.cpp:16:2:16:4 | ss1 |  |
+| stringstream.cpp:13:20:13:22 | call to basic_stringstream | stringstream.cpp:22:7:22:9 | ss1 |  |
+| stringstream.cpp:13:20:13:22 | call to basic_stringstream | stringstream.cpp:27:7:27:9 | ss1 |  |
+| stringstream.cpp:13:25:13:27 | call to basic_stringstream | stringstream.cpp:17:2:17:4 | ss2 |  |
+| stringstream.cpp:13:25:13:27 | call to basic_stringstream | stringstream.cpp:23:7:23:9 | ss2 |  |
+| stringstream.cpp:13:25:13:27 | call to basic_stringstream | stringstream.cpp:28:7:28:9 | ss2 |  |
+| stringstream.cpp:13:30:13:32 | call to basic_stringstream | stringstream.cpp:18:2:18:4 | ss3 |  |
+| stringstream.cpp:13:30:13:32 | call to basic_stringstream | stringstream.cpp:24:7:24:9 | ss3 |  |
+| stringstream.cpp:13:30:13:32 | call to basic_stringstream | stringstream.cpp:29:7:29:9 | ss3 |  |
+| stringstream.cpp:13:35:13:37 | call to basic_stringstream | stringstream.cpp:19:2:19:4 | ss4 |  |
+| stringstream.cpp:13:35:13:37 | call to basic_stringstream | stringstream.cpp:25:7:25:9 | ss4 |  |
+| stringstream.cpp:13:35:13:37 | call to basic_stringstream | stringstream.cpp:30:7:30:9 | ss4 |  |
+| stringstream.cpp:13:40:13:42 | call to basic_stringstream | stringstream.cpp:20:2:20:4 | ss5 |  |
+| stringstream.cpp:13:40:13:42 | call to basic_stringstream | stringstream.cpp:26:7:26:9 | ss5 |  |
+| stringstream.cpp:13:40:13:42 | call to basic_stringstream | stringstream.cpp:31:7:31:9 | ss5 |  |
+| stringstream.cpp:14:16:14:21 | call to source | stringstream.cpp:14:16:14:24 | call to basic_string | TAINT |
+| stringstream.cpp:14:16:14:24 | call to basic_string | stringstream.cpp:20:9:20:9 | t |  |
+| stringstream.cpp:16:2:16:4 | ref arg ss1 | stringstream.cpp:22:7:22:9 | ss1 |  |
+| stringstream.cpp:16:2:16:4 | ref arg ss1 | stringstream.cpp:27:7:27:9 | ss1 |  |
+| stringstream.cpp:17:2:17:4 | ref arg ss2 | stringstream.cpp:23:7:23:9 | ss2 |  |
+| stringstream.cpp:17:2:17:4 | ref arg ss2 | stringstream.cpp:28:7:28:9 | ss2 |  |
+| stringstream.cpp:18:2:18:4 | ref arg ss3 | stringstream.cpp:24:7:24:9 | ss3 |  |
+| stringstream.cpp:18:2:18:4 | ref arg ss3 | stringstream.cpp:29:7:29:9 | ss3 |  |
+| stringstream.cpp:19:2:19:4 | ref arg ss4 | stringstream.cpp:25:7:25:9 | ss4 |  |
+| stringstream.cpp:19:2:19:4 | ref arg ss4 | stringstream.cpp:30:7:30:9 | ss4 |  |
+| stringstream.cpp:20:2:20:4 | ref arg ss5 | stringstream.cpp:26:7:26:9 | ss5 |  |
+| stringstream.cpp:20:2:20:4 | ref arg ss5 | stringstream.cpp:31:7:31:9 | ss5 |  |
+| stringstream.cpp:34:32:34:37 | source | stringstream.cpp:39:9:39:14 | source |  |
+| stringstream.cpp:36:20:36:22 | call to basic_stringstream | stringstream.cpp:38:2:38:4 | ss1 |  |
+| stringstream.cpp:36:20:36:22 | call to basic_stringstream | stringstream.cpp:41:7:41:9 | ss1 |  |
+| stringstream.cpp:36:20:36:22 | call to basic_stringstream | stringstream.cpp:43:7:43:9 | ss1 |  |
+| stringstream.cpp:36:25:36:27 | call to basic_stringstream | stringstream.cpp:39:2:39:4 | ss2 |  |
+| stringstream.cpp:36:25:36:27 | call to basic_stringstream | stringstream.cpp:42:7:42:9 | ss2 |  |
+| stringstream.cpp:36:25:36:27 | call to basic_stringstream | stringstream.cpp:44:7:44:9 | ss2 |  |
+| stringstream.cpp:38:2:38:4 | ref arg ss1 | stringstream.cpp:41:7:41:9 | ss1 |  |
+| stringstream.cpp:38:2:38:4 | ref arg ss1 | stringstream.cpp:43:7:43:9 | ss1 |  |
+| stringstream.cpp:39:2:39:4 | ref arg ss2 | stringstream.cpp:42:7:42:9 | ss2 |  |
+| stringstream.cpp:39:2:39:4 | ref arg ss2 | stringstream.cpp:44:7:44:9 | ss2 |  |
 | structlikeclass.cpp:5:7:5:7 | Unknown literal | structlikeclass.cpp:5:7:5:7 | constructor init of field v | TAINT |
 | structlikeclass.cpp:5:7:5:7 | Unknown literal | structlikeclass.cpp:5:7:5:7 | constructor init of field v | TAINT |
 | structlikeclass.cpp:5:7:5:7 | this | structlikeclass.cpp:5:7:5:7 | constructor init of field v [pre-this] |  |
@@ -1199,3 +1330,57 @@
 | taint.cpp:483:18:483:19 | ref arg & ... | taint.cpp:483:19:483:19 | n [inner post update] |  |
 | taint.cpp:483:19:483:19 | n | taint.cpp:483:18:483:19 | & ... |  |
 | taint.cpp:483:28:483:34 | source1 | taint.cpp:483:11:483:15 | ref arg & ... | TAINT |
+| vector.cpp:8:43:8:49 | source1 | vector.cpp:12:21:12:27 | source1 |  |
+| vector.cpp:8:43:8:49 | source1 | vector.cpp:26:33:26:39 | source1 |  |
+| vector.cpp:12:21:12:27 | source1 | vector.cpp:12:21:12:28 | call to vector | TAINT |
+| vector.cpp:12:21:12:28 | call to vector | vector.cpp:14:14:14:14 | v |  |
+| vector.cpp:12:21:12:28 | call to vector | vector.cpp:18:38:18:38 | v |  |
+| vector.cpp:12:21:12:28 | call to vector | vector.cpp:18:55:18:55 | v |  |
+| vector.cpp:12:21:12:28 | call to vector | vector.cpp:22:15:22:15 | v |  |
+| vector.cpp:14:14:14:14 | call to begin | vector.cpp:14:14:14:14 | (__begin) |  |
+| vector.cpp:14:14:14:14 | call to begin | vector.cpp:14:14:14:14 | (__begin) |  |
+| vector.cpp:14:14:14:14 | call to begin | vector.cpp:14:14:14:14 | (__begin) |  |
+| vector.cpp:14:14:14:14 | call to end | vector.cpp:14:14:14:14 | (__end) |  |
+| vector.cpp:14:14:14:14 | call to operator* | vector.cpp:15:8:15:8 | x |  |
+| vector.cpp:14:14:14:14 | ref arg (__begin) | vector.cpp:14:14:14:14 | (__begin) |  |
+| vector.cpp:14:14:14:14 | ref arg (__begin) | vector.cpp:14:14:14:14 | (__begin) |  |
+| vector.cpp:14:14:14:14 | ref arg (__begin) | vector.cpp:14:14:14:14 | (__begin) |  |
+| vector.cpp:14:14:14:14 | ref arg (__range) | vector.cpp:14:14:14:14 | (__range) |  |
+| vector.cpp:14:14:14:14 | v | vector.cpp:14:14:14:14 | (__range) |  |
+| vector.cpp:14:14:14:14 | v | vector.cpp:14:14:14:14 | (__range) |  |
+| vector.cpp:14:14:14:14 | v | vector.cpp:14:14:14:14 | call to operator* | TAINT |
+| vector.cpp:18:38:18:38 | ref arg v | vector.cpp:18:55:18:55 | v |  |
+| vector.cpp:18:38:18:38 | ref arg v | vector.cpp:22:15:22:15 | v |  |
+| vector.cpp:18:40:18:44 | call to begin | vector.cpp:18:49:18:50 | it |  |
+| vector.cpp:18:40:18:44 | call to begin | vector.cpp:18:66:18:67 | it |  |
+| vector.cpp:18:40:18:44 | call to begin | vector.cpp:19:9:19:10 | it |  |
+| vector.cpp:18:55:18:55 | ref arg v | vector.cpp:18:55:18:55 | v |  |
+| vector.cpp:18:55:18:55 | ref arg v | vector.cpp:22:15:22:15 | v |  |
+| vector.cpp:18:66:18:67 | ref arg it | vector.cpp:18:49:18:50 | it |  |
+| vector.cpp:18:66:18:67 | ref arg it | vector.cpp:18:66:18:67 | it |  |
+| vector.cpp:18:66:18:67 | ref arg it | vector.cpp:19:9:19:10 | it |  |
+| vector.cpp:22:15:22:15 | call to begin | vector.cpp:22:15:22:15 | (__begin) |  |
+| vector.cpp:22:15:22:15 | call to begin | vector.cpp:22:15:22:15 | (__begin) |  |
+| vector.cpp:22:15:22:15 | call to begin | vector.cpp:22:15:22:15 | (__begin) |  |
+| vector.cpp:22:15:22:15 | call to end | vector.cpp:22:15:22:15 | (__end) |  |
+| vector.cpp:22:15:22:15 | call to operator* | vector.cpp:23:8:23:8 | x |  |
+| vector.cpp:22:15:22:15 | ref arg (__begin) | vector.cpp:22:15:22:15 | (__begin) |  |
+| vector.cpp:22:15:22:15 | ref arg (__begin) | vector.cpp:22:15:22:15 | (__begin) |  |
+| vector.cpp:22:15:22:15 | ref arg (__begin) | vector.cpp:22:15:22:15 | (__begin) |  |
+| vector.cpp:22:15:22:15 | ref arg (__range) | vector.cpp:22:15:22:15 | (__range) |  |
+| vector.cpp:22:15:22:15 | v | vector.cpp:22:15:22:15 | (__range) |  |
+| vector.cpp:22:15:22:15 | v | vector.cpp:22:15:22:15 | (__range) |  |
+| vector.cpp:22:15:22:15 | v | vector.cpp:22:15:22:15 | call to operator* | TAINT |
+| vector.cpp:26:33:26:39 | source1 | vector.cpp:26:33:26:40 | call to vector | TAINT |
+| vector.cpp:26:33:26:40 | call to vector | vector.cpp:27:21:27:27 | const_v |  |
+| vector.cpp:27:21:27:21 | call to begin | vector.cpp:27:21:27:21 | (__begin) |  |
+| vector.cpp:27:21:27:21 | call to begin | vector.cpp:27:21:27:21 | (__begin) |  |
+| vector.cpp:27:21:27:21 | call to begin | vector.cpp:27:21:27:21 | (__begin) |  |
+| vector.cpp:27:21:27:21 | call to end | vector.cpp:27:21:27:21 | (__end) |  |
+| vector.cpp:27:21:27:21 | call to operator* | vector.cpp:28:8:28:8 | x |  |
+| vector.cpp:27:21:27:21 | ref arg (__begin) | vector.cpp:27:21:27:21 | (__begin) |  |
+| vector.cpp:27:21:27:21 | ref arg (__begin) | vector.cpp:27:21:27:21 | (__begin) |  |
+| vector.cpp:27:21:27:21 | ref arg (__begin) | vector.cpp:27:21:27:21 | (__begin) |  |
+| vector.cpp:27:21:27:27 | const_v | vector.cpp:27:21:27:21 | (__range) |  |
+| vector.cpp:27:21:27:27 | const_v | vector.cpp:27:21:27:21 | (__range) |  |
+| vector.cpp:27:21:27:27 | const_v | vector.cpp:27:21:27:21 | call to operator* | TAINT |

cpp/ql/test/library-tests/dataflow/taint-tests/stl.cpp

@@ -1,204 +0,0 @@
-
-typedef unsigned long size_t;
-
-namespace std
-{
-	template<class charT> struct char_traits;
-
-	typedef size_t streamsize;
-
-	template <class T> class allocator {
-	public:
-		allocator() throw();
-	};
-	
-	template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-	class basic_string {
-	public:
-		explicit basic_string(const Allocator& a = Allocator());
-		basic_string(const charT* s, const Allocator& a = Allocator());
-
-		const charT* c_str() const;
-	};
-
-	typedef basic_string<char> string;
-
-	template <class charT, class traits = char_traits<charT> >
-	class basic_istream /*: virtual public basic_ios<charT,traits> - not needed for this test */ {
-	public:
-		basic_istream<charT,traits>& operator>>(int& n);
-	};
-
-	template <class charT, class traits = char_traits<charT> >
-	class basic_ostream /*: virtual public basic_ios<charT,traits> - not needed for this test */ {
-	public:
-		typedef charT char_type;
-		basic_ostream<charT,traits>& write(const char_type* s, streamsize n);
-
-		basic_ostream<charT, traits>& operator<<(int n);
-	};
-
-	template<class charT, class traits> basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>&, const charT*);
-	template<class charT, class traits, class Allocator> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str); 
-
-	template<class charT, class traits = char_traits<charT>>
-	class basic_iostream : public basic_istream<charT, traits>, public basic_ostream<charT, traits> {
-	public:
-	};
-
-	template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>
-	class basic_stringstream : public basic_iostream<charT, traits> {
-	public:
-		explicit basic_stringstream(/*ios_base::openmode which = ios_base::out|ios_base::in - not needed for this test*/);
-
-		basic_string<charT, traits, Allocator> str() const;
-	};
-
-	using stringstream = basic_stringstream<char>;
-}
-
-char *source();
-void sink(const char *s) {};
-void sink(const std::string &s) {};
-void sink(const std::stringstream &s) {};
-
-void test_string()
-{
-	char *a = source();
-	std::string b("123");
-	std::string c(source());
-
-	sink(a); // tainted
-	sink(b);
-	sink(c); // tainted
-	sink(b.c_str());
-	sink(c.c_str()); // tainted
-}
-
-void test_stringstream()
-{
-	std::stringstream ss1, ss2, ss3, ss4, ss5;
-	std::string t(source());
-
-	ss1 << "1234";
-	ss2 << source();
-	ss3 << "123" << source();
-	ss4 << source() << "456";
-	ss5 << t;
-
-	sink(ss1);
-	sink(ss2); // tainted [NOT DETECTED]
-	sink(ss3); // tainted [NOT DETECTED]
-	sink(ss4); // tainted [NOT DETECTED]
-	sink(ss5); // tainted [NOT DETECTED]
-	sink(ss1.str());
-	sink(ss2.str()); // tainted [NOT DETECTED]
-	sink(ss3.str()); // tainted [NOT DETECTED]
-	sink(ss4.str()); // tainted [NOT DETECTED]
-	sink(ss5.str()); // tainted [NOT DETECTED]
-}
-
-void test_stringstream_int(int source)
-{
-	std::stringstream ss1, ss2;
-
-	ss1 << 1234;
-	ss2 << source;
-
-	sink(ss1);
-	sink(ss2); // tainted [NOT DETECTED]
-	sink(ss1.str());
-	sink(ss2.str()); // tainted [NOT DETECTED]
-}
-
-using namespace std;
-
-char *user_input() {
-  return source();
-}
-
-void sink(const char *filename, const char *mode);
-
-void test_strings2()
-{
-	string path1 = user_input();
-	sink(path1.c_str(), "r"); // tainted
-
-	string path2;
-	path2 = user_input();
-	sink(path2.c_str(), "r"); // tainted
-
-	string path3(user_input());
-	sink(path3.c_str(), "r"); // tainted
-}
-
-void test_string3()
-{
-	const char *cs = source();
-
-	// convert char * -> std::string
-	std::string ss(cs);
-
-	sink(cs); // tainted
-	sink(ss); // tainted
-}
-
-void test_string4()
-{
-	const char *cs = source();
-
-	// convert char * -> std::string
-	std::string ss(cs);
-
-	// convert back std::string -> char *
-	cs = ss.c_str();
-
-	sink(cs); // tainted
-	sink(ss); // tainted
-}
-
-void test_string_constructors_assignments()
-{
-	{
-		std::string s1("hello");
-		std::string s2 = "hello";
-		std::string s3;
-		s3 = "hello";
-
-		sink(s1);
-		sink(s2);
-		sink(s3);
-	}
-
-	{
-		std::string s1(source());
-		std::string s2 = source();
-		std::string s3;
-		s3 = source();
-
-		sink(s1); // tainted
-		sink(s2); // tainted
-		sink(s3); // tainted
-	}
-
-	{
-		std::string s1;
-		std::string s2 = s1;
-		std::string s3;
-		s3 = s1;
-
-		sink(s1);
-		sink(s2);
-		sink(s3);
-	}
-
-	{
-		std::string s1 = std::string(source());
-		std::string s2;
-		s2 = std::string(source());
-
-		sink(s1); // tainted
-		sink(s2); // tainted
-	}
-}
-

cpp/ql/test/library-tests/dataflow/taint-tests/stl.h

@@ -0,0 +1,126 @@
+
+typedef unsigned long size_t;
+
+// --- string ---
+
+namespace std
+{
+	template<class charT> struct char_traits;
+
+	typedef size_t streamsize;
+
+	struct ptrdiff_t;
+
+	template <class iterator_category,
+			  class value_type,
+			  class difference_type = ptrdiff_t,
+			  class pointer_type = value_type*,
+			  class reference_type = value_type&>
+	struct iterator {
+		iterator &operator++();
+		iterator operator++(int);
+		bool operator==(iterator other) const;
+		bool operator!=(iterator other) const;
+		reference_type operator*() const;
+	};
+
+	struct input_iterator_tag {};
+	struct forward_iterator_tag : public input_iterator_tag {};
+	struct bidirectional_iterator_tag : public forward_iterator_tag {};
+	struct random_access_iterator_tag : public bidirectional_iterator_tag {};
+
+	template <class T> class allocator {
+	public:
+		allocator() throw();
+		typedef size_t size_type;
+	};
+	
+	template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
+	class basic_string {
+	public:
+		typedef typename Allocator::size_type size_type;
+
+		explicit basic_string(const Allocator& a = Allocator());
+		basic_string(const charT* s, const Allocator& a = Allocator());
+
+		const charT* c_str() const;
+
+		typedef std::iterator<random_access_iterator_tag, charT> iterator;
+		typedef std::iterator<random_access_iterator_tag, const charT> const_iterator;
+
+		iterator begin();
+		iterator end();
+		const_iterator begin() const;
+		const_iterator end() const;
+		const_iterator cbegin() const;
+		const_iterator cend() const;
+
+		template<class T> basic_string& operator+=(const T& t);
+		basic_string& operator+=(const charT* s);
+		basic_string& append(const basic_string& str);
+		basic_string& append(const charT* s);
+		basic_string& append(size_type n, charT c);
+	};
+
+	template<class charT, class traits, class Allocator> basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, const basic_string<charT, traits, Allocator>& rhs);
+	template<class charT, class traits, class Allocator> basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
+
+	typedef basic_string<char> string;
+
+	template <class charT, class traits = char_traits<charT> >
+	class basic_istream /*: virtual public basic_ios<charT,traits> - not needed for this test */ {
+	public:
+		basic_istream<charT,traits>& operator>>(int& n);
+	};
+
+	template <class charT, class traits = char_traits<charT> >
+	class basic_ostream /*: virtual public basic_ios<charT,traits> - not needed for this test */ {
+	public:
+		typedef charT char_type;
+		basic_ostream<charT,traits>& write(const char_type* s, streamsize n);
+
+		basic_ostream<charT, traits>& operator<<(int n);
+	};
+
+	template<class charT, class traits> basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>&, const charT*);
+	template<class charT, class traits, class Allocator> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str); 
+
+	template<class charT, class traits = char_traits<charT>>
+	class basic_iostream : public basic_istream<charT, traits>, public basic_ostream<charT, traits> {
+	public:
+	};
+
+	template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>
+	class basic_stringstream : public basic_iostream<charT, traits> {
+	public:
+		explicit basic_stringstream(/*ios_base::openmode which = ios_base::out|ios_base::in - not needed for this test*/);
+
+		basic_string<charT, traits, Allocator> str() const;
+	};
+
+	using stringstream = basic_stringstream<char>;
+}
+
+// --- vector ---
+
+namespace std {
+	template <class T>
+	class vector {
+	private:
+		void *data_;
+	public:
+		vector(int size);
+
+		T& operator[](int idx);
+		const T& operator[](int idx) const;
+
+		typedef std::iterator<random_access_iterator_tag, T> iterator;
+		typedef std::iterator<random_access_iterator_tag, const T> const_iterator;
+
+		iterator begin() noexcept;
+		iterator end() noexcept;
+
+		const_iterator begin() const noexcept;
+		const_iterator end() const noexcept;
+	};
+}

cpp/ql/test/library-tests/dataflow/taint-tests/string.cpp

@@ -0,0 +1,186 @@
+
+#include "stl.h"
+
+using namespace std;
+
+char *source();
+
+namespace ns_char
+{
+	char source();
+}
+
+char *user_input() {
+  return source();
+}
+
+void sink(const char *s) {};
+void sink(const std::string &s) {};
+void sink(const char *filename, const char *mode);
+void sink(char) {}
+
+void test_string()
+{
+	char *a = source();
+	std::string b("123");
+	std::string c(source());
+
+	sink(a); // tainted
+	sink(b);
+	sink(c); // tainted
+	sink(b.c_str());
+	sink(c.c_str()); // tainted
+}
+
+void test_strings2()
+{
+	string path1 = user_input();
+	sink(path1.c_str(), "r"); // tainted
+
+	string path2;
+	path2 = user_input();
+	sink(path2.c_str(), "r"); // tainted
+
+	string path3(user_input());
+	sink(path3.c_str(), "r"); // tainted
+}
+
+void test_string3()
+{
+	const char *cs = source();
+
+	// convert char * -> std::string
+	std::string ss(cs);
+
+	sink(cs); // tainted
+	sink(ss); // tainted
+}
+
+void test_string4()
+{
+	const char *cs = source();
+
+	// convert char * -> std::string
+	std::string ss(cs);
+
+	// convert back std::string -> char *
+	cs = ss.c_str();
+
+	sink(cs); // tainted
+	sink(ss); // tainted
+}
+
+void test_string_constructors_assignments()
+{
+	{
+		std::string s1("hello");
+		std::string s2 = "hello";
+		std::string s3;
+		s3 = "hello";
+
+		sink(s1);
+		sink(s2);
+		sink(s3);
+	}
+
+	{
+		std::string s1(source());
+		std::string s2 = source();
+		std::string s3;
+		s3 = source();
+
+		sink(s1); // tainted
+		sink(s2); // tainted
+		sink(s3); // tainted
+	}
+
+	{
+		std::string s1;
+		std::string s2 = s1;
+		std::string s3;
+		s3 = s1;
+
+		sink(s1);
+		sink(s2);
+		sink(s3);
+	}
+
+	{
+		std::string s1 = std::string(source());
+		std::string s2;
+		s2 = std::string(source());
+
+		sink(s1); // tainted
+		sink(s2); // tainted
+	}
+}
+
+void test_range_based_for_loop_string() {
+	std::string s(source());
+	for(char c : s) {
+		sink(c); // tainted [NOT DETECTED by IR]
+	}
+
+	for(std::string::iterator it = s.begin(); it != s.end(); ++it) {
+		sink(*it); // tainted [NOT DETECTED]
+	}
+
+	for(char& c : s) {
+		sink(c); // tainted [NOT DETECTED by IR]
+	}
+
+	const std::string const_s(source());
+	for(const char& c : const_s) {
+		sink(c); // tainted [NOT DETECTED by IR]
+	}
+}
+
+void test_string_append() {
+	{
+		std::string s1("hello");
+		std::string s2(source());
+
+		sink(s1 + s1);
+		sink(s1 + s2); // tainted
+		sink(s2 + s1); // tainted
+		sink(s2 + s2); // tainted
+	
+		sink(s1 + " world");
+		sink(s1 + source()); // tainted
+	}
+
+	{
+		std::string s3("abc");
+		std::string s4(source());
+		std::string s5, s6, s7, s8, s9;
+
+		s5 = s3 + s4;
+		sink(s5); // tainted
+
+		s6 = s3;
+		s6 += s4;
+		sink(s6); // tainted
+
+		s7 = s3;
+		s7 += source();
+		s7 += " ";
+		sink(s7); // tainted
+
+		s8 = s3;
+		s8.append(s4);
+		sink(s8); // tainted
+
+		s9 = s3;
+		s9.append(source());
+		s9.append(" ");
+		sink(s9); // tainted
+	}
+
+	{
+		std::string s10("abc");
+		char c = ns_char::source();
+
+		s10.append(1, c);
+		sink(s10); // tainted
+	}
+}

cpp/ql/test/library-tests/dataflow/taint-tests/stringstream.cpp

@@ -0,0 +1,45 @@
+
+#include "stl.h"
+
+using namespace std;
+
+char *source();
+
+void sink(const std::string &s) {};
+void sink(const std::stringstream &s) {};
+
+void test_stringstream()
+{
+	std::stringstream ss1, ss2, ss3, ss4, ss5;
+	std::string t(source());
+
+	ss1 << "1234";
+	ss2 << source();
+	ss3 << "123" << source();
+	ss4 << source() << "456";
+	ss5 << t;
+
+	sink(ss1);
+	sink(ss2); // tainted [NOT DETECTED]
+	sink(ss3); // tainted [NOT DETECTED]
+	sink(ss4); // tainted [NOT DETECTED]
+	sink(ss5); // tainted [NOT DETECTED]
+	sink(ss1.str());
+	sink(ss2.str()); // tainted [NOT DETECTED]
+	sink(ss3.str()); // tainted [NOT DETECTED]
+	sink(ss4.str()); // tainted [NOT DETECTED]
+	sink(ss5.str()); // tainted [NOT DETECTED]
+}
+
+void test_stringstream_int(int source)
+{
+	std::stringstream ss1, ss2;
+
+	ss1 << 1234;
+	ss2 << source;
+
+	sink(ss1);
+	sink(ss2); // tainted [NOT DETECTED]
+	sink(ss1.str());
+	sink(ss2.str()); // tainted [NOT DETECTED]
+}

cpp/ql/test/library-tests/dataflow/taint-tests/taint.expected

@@ -32,21 +32,34 @@
 | movableclass.cpp:55:8:55:9 | s2 | movableclass.cpp:52:23:52:28 | call to source |
 | movableclass.cpp:64:8:64:9 | s2 | movableclass.cpp:23:55:23:60 | call to source |
 | movableclass.cpp:65:11:65:11 | call to operator= | movableclass.cpp:65:13:65:18 | call to source |
-| stl.cpp:71:7:71:7 | a | stl.cpp:67:12:67:17 | call to source |
-| stl.cpp:73:7:73:7 | c | stl.cpp:69:16:69:21 | call to source |
-| stl.cpp:75:9:75:13 | call to c_str | stl.cpp:69:16:69:21 | call to source |
-| stl.cpp:125:13:125:17 | call to c_str | stl.cpp:117:10:117:15 | call to source |
-| stl.cpp:129:13:129:17 | call to c_str | stl.cpp:117:10:117:15 | call to source |
-| stl.cpp:132:13:132:17 | call to c_str | stl.cpp:117:10:117:15 | call to source |
-| stl.cpp:142:7:142:8 | cs | stl.cpp:137:19:137:24 | call to source |
-| stl.cpp:143:7:143:8 | ss | stl.cpp:137:19:137:24 | call to source |
-| stl.cpp:156:7:156:8 | cs | stl.cpp:148:19:148:24 | call to source |
-| stl.cpp:157:7:157:8 | ss | stl.cpp:148:19:148:24 | call to source |
-| stl.cpp:179:8:179:9 | s1 | stl.cpp:174:18:174:23 | call to source |
-| stl.cpp:180:8:180:9 | s2 | stl.cpp:175:20:175:25 | call to source |
-| stl.cpp:181:8:181:9 | s3 | stl.cpp:177:8:177:13 | call to source |
-| stl.cpp:200:8:200:9 | s1 | stl.cpp:196:32:196:37 | call to source |
-| stl.cpp:201:8:201:9 | s2 | stl.cpp:198:20:198:25 | call to source |
+| string.cpp:28:7:28:7 | a | string.cpp:24:12:24:17 | call to source |
+| string.cpp:30:7:30:7 | c | string.cpp:26:16:26:21 | call to source |
+| string.cpp:32:9:32:13 | call to c_str | string.cpp:26:16:26:21 | call to source |
+| string.cpp:38:13:38:17 | call to c_str | string.cpp:14:10:14:15 | call to source |
+| string.cpp:42:13:42:17 | call to c_str | string.cpp:14:10:14:15 | call to source |
+| string.cpp:45:13:45:17 | call to c_str | string.cpp:14:10:14:15 | call to source |
+| string.cpp:55:7:55:8 | cs | string.cpp:50:19:50:24 | call to source |
+| string.cpp:56:7:56:8 | ss | string.cpp:50:19:50:24 | call to source |
+| string.cpp:69:7:69:8 | cs | string.cpp:61:19:61:24 | call to source |
+| string.cpp:70:7:70:8 | ss | string.cpp:61:19:61:24 | call to source |
+| string.cpp:92:8:92:9 | s1 | string.cpp:87:18:87:23 | call to source |
+| string.cpp:93:8:93:9 | s2 | string.cpp:88:20:88:25 | call to source |
+| string.cpp:94:8:94:9 | s3 | string.cpp:90:8:90:13 | call to source |
+| string.cpp:113:8:113:9 | s1 | string.cpp:109:32:109:37 | call to source |
+| string.cpp:114:8:114:9 | s2 | string.cpp:111:20:111:25 | call to source |
+| string.cpp:121:8:121:8 | c | string.cpp:119:16:119:21 | call to source |
+| string.cpp:129:8:129:8 | c | string.cpp:119:16:119:21 | call to source |
+| string.cpp:134:8:134:8 | c | string.cpp:132:28:132:33 | call to source |
+| string.cpp:144:11:144:11 | call to operator+ | string.cpp:141:18:141:23 | call to source |
+| string.cpp:145:11:145:11 | call to operator+ | string.cpp:141:18:141:23 | call to source |
+| string.cpp:146:11:146:11 | call to operator+ | string.cpp:141:18:141:23 | call to source |
+| string.cpp:149:11:149:11 | call to operator+ | string.cpp:149:13:149:18 | call to source |
+| string.cpp:158:8:158:9 | s5 | string.cpp:154:18:154:23 | call to source |
+| string.cpp:162:8:162:9 | s6 | string.cpp:154:18:154:23 | call to source |
+| string.cpp:167:8:167:9 | s7 | string.cpp:165:9:165:14 | call to source |
+| string.cpp:171:8:171:9 | s8 | string.cpp:154:18:154:23 | call to source |
+| string.cpp:176:8:176:9 | s9 | string.cpp:174:13:174:18 | call to source |
+| string.cpp:184:8:184:10 | s10 | string.cpp:181:12:181:26 | call to source |
 | structlikeclass.cpp:35:8:35:9 | s1 | structlikeclass.cpp:29:22:29:27 | call to source |
 | structlikeclass.cpp:36:8:36:9 | s2 | structlikeclass.cpp:30:24:30:29 | call to source |
 | structlikeclass.cpp:37:8:37:9 | s3 | structlikeclass.cpp:29:22:29:27 | call to source |
@@ -153,3 +166,6 @@
 | taint.cpp:470:7:470:7 | x | taint.cpp:462:6:462:11 | call to source |
 | taint.cpp:471:7:471:7 | y | taint.cpp:462:6:462:11 | call to source |
 | taint.cpp:485:7:485:10 | line | taint.cpp:480:26:480:32 | source1 |
+| vector.cpp:15:8:15:8 | x | vector.cpp:8:43:8:49 | source1 |
+| vector.cpp:23:8:23:8 | x | vector.cpp:8:43:8:49 | source1 |
+| vector.cpp:28:8:28:8 | x | vector.cpp:8:43:8:49 | source1 |

cpp/ql/test/library-tests/dataflow/taint-tests/test_diff.expected

@@ -30,20 +30,33 @@
 | movableclass.cpp:55:8:55:9 | movableclass.cpp:52:23:52:28 | AST only |
 | movableclass.cpp:64:8:64:9 | movableclass.cpp:23:55:23:60 | AST only |
 | movableclass.cpp:65:11:65:11 | movableclass.cpp:65:13:65:18 | AST only |
-| stl.cpp:73:7:73:7 | stl.cpp:69:16:69:21 | AST only |
-| stl.cpp:75:9:75:13 | stl.cpp:69:16:69:21 | AST only |
-| stl.cpp:125:13:125:17 | stl.cpp:117:10:117:15 | AST only |
-| stl.cpp:129:13:129:17 | stl.cpp:117:10:117:15 | AST only |
-| stl.cpp:132:13:132:17 | stl.cpp:117:10:117:15 | AST only |
-| stl.cpp:142:7:142:8 | stl.cpp:137:19:137:26 | IR only |
-| stl.cpp:143:7:143:8 | stl.cpp:137:19:137:24 | AST only |
-| stl.cpp:156:7:156:8 | stl.cpp:148:19:148:24 | AST only |
-| stl.cpp:157:7:157:8 | stl.cpp:148:19:148:24 | AST only |
-| stl.cpp:179:8:179:9 | stl.cpp:174:18:174:23 | AST only |
-| stl.cpp:180:8:180:9 | stl.cpp:175:20:175:25 | AST only |
-| stl.cpp:181:8:181:9 | stl.cpp:177:8:177:13 | AST only |
-| stl.cpp:200:8:200:9 | stl.cpp:196:32:196:37 | AST only |
-| stl.cpp:201:8:201:9 | stl.cpp:198:20:198:25 | AST only |
+| string.cpp:30:7:30:7 | string.cpp:26:16:26:21 | AST only |
+| string.cpp:32:9:32:13 | string.cpp:26:16:26:21 | AST only |
+| string.cpp:38:13:38:17 | string.cpp:14:10:14:15 | AST only |
+| string.cpp:42:13:42:17 | string.cpp:14:10:14:15 | AST only |
+| string.cpp:45:13:45:17 | string.cpp:14:10:14:15 | AST only |
+| string.cpp:55:7:55:8 | string.cpp:50:19:50:26 | IR only |
+| string.cpp:56:7:56:8 | string.cpp:50:19:50:24 | AST only |
+| string.cpp:69:7:69:8 | string.cpp:61:19:61:24 | AST only |
+| string.cpp:70:7:70:8 | string.cpp:61:19:61:24 | AST only |
+| string.cpp:92:8:92:9 | string.cpp:87:18:87:23 | AST only |
+| string.cpp:93:8:93:9 | string.cpp:88:20:88:25 | AST only |
+| string.cpp:94:8:94:9 | string.cpp:90:8:90:13 | AST only |
+| string.cpp:113:8:113:9 | string.cpp:109:32:109:37 | AST only |
+| string.cpp:114:8:114:9 | string.cpp:111:20:111:25 | AST only |
+| string.cpp:121:8:121:8 | string.cpp:119:16:119:21 | AST only |
+| string.cpp:129:8:129:8 | string.cpp:119:16:119:21 | AST only |
+| string.cpp:134:8:134:8 | string.cpp:132:28:132:33 | AST only |
+| string.cpp:144:11:144:11 | string.cpp:141:18:141:23 | AST only |
+| string.cpp:145:11:145:11 | string.cpp:141:18:141:23 | AST only |
+| string.cpp:146:11:146:11 | string.cpp:141:18:141:23 | AST only |
+| string.cpp:149:11:149:11 | string.cpp:149:13:149:18 | AST only |
+| string.cpp:158:8:158:9 | string.cpp:154:18:154:23 | AST only |
+| string.cpp:162:8:162:9 | string.cpp:154:18:154:23 | AST only |
+| string.cpp:167:8:167:9 | string.cpp:165:9:165:14 | AST only |
+| string.cpp:171:8:171:9 | string.cpp:154:18:154:23 | AST only |
+| string.cpp:176:8:176:9 | string.cpp:174:13:174:18 | AST only |
+| string.cpp:184:8:184:10 | string.cpp:181:12:181:26 | AST only |
 | structlikeclass.cpp:35:8:35:9 | structlikeclass.cpp:29:22:29:27 | AST only |
 | structlikeclass.cpp:36:8:36:9 | structlikeclass.cpp:30:24:30:29 | AST only |
 | structlikeclass.cpp:37:8:37:9 | structlikeclass.cpp:29:22:29:27 | AST only |
@@ -88,3 +101,6 @@
 | taint.cpp:446:7:446:7 | taint.cpp:445:14:445:28 | AST only |
 | taint.cpp:447:9:447:17 | taint.cpp:445:14:445:28 | AST only |
 | taint.cpp:471:7:471:7 | taint.cpp:462:6:462:11 | AST only |
+| vector.cpp:15:8:15:8 | vector.cpp:8:43:8:49 | AST only |
+| vector.cpp:23:8:23:8 | vector.cpp:8:43:8:49 | AST only |
+| vector.cpp:28:8:28:8 | vector.cpp:8:43:8:49 | AST only |

cpp/ql/test/library-tests/dataflow/taint-tests/test_ir.expected

@@ -1,10 +1,10 @@
 | format.cpp:157:7:157:22 | (int)... | format.cpp:147:12:147:25 | call to source |
 | format.cpp:157:7:157:22 | access to array | format.cpp:147:12:147:25 | call to source |
 | format.cpp:158:7:158:27 | ... + ... | format.cpp:148:16:148:30 | call to source |
-| stl.cpp:71:7:71:7 | (const char *)... | stl.cpp:67:12:67:17 | call to source |
-| stl.cpp:71:7:71:7 | a | stl.cpp:67:12:67:17 | call to source |
-| stl.cpp:142:7:142:8 | cs | stl.cpp:137:19:137:24 | call to source |
-| stl.cpp:142:7:142:8 | cs | stl.cpp:137:19:137:26 | (const char *)... |
+| string.cpp:28:7:28:7 | (const char *)... | string.cpp:24:12:24:17 | call to source |
+| string.cpp:28:7:28:7 | a | string.cpp:24:12:24:17 | call to source |
+| string.cpp:55:7:55:8 | cs | string.cpp:50:19:50:24 | call to source |
+| string.cpp:55:7:55:8 | cs | string.cpp:50:19:50:26 | (const char *)... |
 | structlikeclass.cpp:38:8:38:9 | s4 | structlikeclass.cpp:33:8:33:13 | call to source |
 | structlikeclass.cpp:61:8:61:9 | s2 | structlikeclass.cpp:58:24:58:29 | call to source |
 | structlikeclass.cpp:62:8:62:20 | ... = ... | structlikeclass.cpp:62:13:62:18 | call to source |

cpp/ql/test/library-tests/dataflow/taint-tests/vector.cpp

@@ -0,0 +1,30 @@
+
+#include "stl.h"
+
+using namespace std;
+
+void sink(int);
+
+void test_range_based_for_loop_vector(int source1) {
+	// Tainting the vector by allocating a tainted length. This doesn't represent
+	// how a vector would typically get tainted, but it allows this test to avoid
+	// being concerned with std::vector modeling.
+	std::vector<int> v(source1);
+
+	for(int x : v) {
+		sink(x); // tainted [NOT DETECTED by IR]
+	}
+
+	for(std::vector<int>::iterator it = v.begin(); it != v.end(); ++it) {
+		sink(*it); // tainted [NOT DETECTED]
+	}
+
+	for(int& x : v) {
+		sink(x); // tainted [NOT DETECTED by IR]
+	}
+
+	const std::vector<int> const_v(source1);
+	for(const int& x : const_v) {
+		sink(x); // tainted [NOT DETECTED by IR]
+	}
+}

cpp/ql/test/library-tests/functions/functions/Functions2.expected

@@ -20,7 +20,7 @@
 | functions.cpp:23:7:23:11 | Table | Class | functions.cpp:30:8:30:13 | insert |  |
 | functions.cpp:33:7:33:13 | MyClass | Class | functions.cpp:33:7:33:7 | operator= |  |
 | functions.cpp:33:7:33:13 | MyClass | Class | functions.cpp:36:2:36:8 | MyClass | Constructor, NoArgConstructor, getAConstructor() |
-| functions.cpp:33:7:33:13 | MyClass | Class | functions.cpp:37:2:37:8 | MyClass | Constructor, ConversionConstructor, getAConstructor() |
+| functions.cpp:33:7:33:13 | MyClass | Class | functions.cpp:37:2:37:8 | MyClass | Constructor, getAConstructor() |
 | functions.cpp:33:7:33:13 | MyClass | Class | functions.cpp:38:2:38:8 | MyClass | Constructor, CopyConstructor, getAConstructor() |
-| functions.cpp:33:7:33:13 | MyClass | Class | functions.cpp:39:2:39:8 | MyClass | Constructor, ConversionConstructor, MoveConstructor, getAConstructor() |
+| functions.cpp:33:7:33:13 | MyClass | Class | functions.cpp:39:2:39:8 | MyClass | Constructor, MoveConstructor, getAConstructor() |
 | functions.cpp:33:7:33:13 | MyClass | Class | functions.cpp:40:2:40:13 | operator int | ConversionOperator |

cpp/ql/test/library-tests/functions/functions/Functions2.ql

@@ -19,9 +19,6 @@ string describe(Class c, MemberFunction f) {
   f instanceof Destructor and
   result = "Destructor"
   or
-  f instanceof ConversionConstructor and
-  result = "ConversionConstructor"
-  or
   f instanceof CopyConstructor and
   result = "CopyConstructor"
   or

cpp/ql/test/library-tests/ir/ssa/ssa.cpp

@@ -291,7 +291,7 @@ struct A {
 Point *NewAliasing(int x) {
   Point* p = new Point;
   Point* q = new Point;
-  int j = new A(new A(x))->i;
+  int j = (new A(new A(x)))->i;
   A* a = new A;
   return p;
 }
@@ -310,4 +310,4 @@ class ThisAliasTest {
   void setX(int arg) {
     this->x = arg;
   }
-};
+};

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/lowerBound.ql

@@ -1,4 +1,4 @@
 import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
 
 from VariableAccess expr
-select expr, lowerBound(expr)
+select expr, lowerBound(expr).toString()

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/test.c

@@ -422,7 +422,7 @@ void test17() {
   out(i); // 50
 
   i = 20 + (j -= 10);
-  out(i); // 60 [BUG: the analysis thinks it's 2^-31 .. 2^31-1]
+  out(i); // 60
 }
 
 // Tests for unsigned multiplication.
@@ -463,3 +463,30 @@ int test_unsigned_mult02(unsigned b) {
 
   return total;
 }
+
+unsigned long mult_rounding() {
+  unsigned long x, y, xy;
+  x = y = 1000000003UL; // 1e9 + 3
+  xy = x * y;
+  return xy; // BUG: upper bound should be >= 1000000006000000009UL
+}
+
+unsigned long mult_overflow() {
+  unsigned long x, y, xy;
+  x = 274177UL;
+  y = 67280421310721UL;
+  xy = x * y;
+  return xy; // BUG: lower bound should be <= 18446744073709551617UL
+}
+
+unsigned long mult_lower_bound(unsigned int ui, unsigned long ul) {
+  if (ui >= 10) {
+    unsigned long result = (unsigned long)ui * ui;
+    return result; // BUG: upper bound should be >= 18446744065119617025 (possibly a pretty-printing bug)
+  }
+  if (ul >= 10) {
+    unsigned long result = ul * ul;
+    return result; // lower bound is correctly 0 (overflow is possible)
+  }
+  return 0;
+}

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/upperBound.ql

@@ -1,4 +1,4 @@
 import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
 
 from VariableAccess expr
-select expr, upperBound(expr)
+select expr, upperBound(expr).toString()

cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.c

@@ -385,10 +385,39 @@ void bitwise_ands()
 
 void unsigned_mult(unsigned int x, unsigned int y) {
   if(x < 13 && y < 35) {
-      if(x * y > 1024) {} // always false [NOT DETECTED]
+      if(x * y > 1024) {} // always false
       if(x * y < 204) {}
       if(x >= 3 && y >= 2) {
-        if(x * y < 5) {} // always false [NOT DETECTED]
+        if(x * y < 5) {} // always false
       }
   }
-}
+}
+
+void mult_rounding() {
+  unsigned long x, y, xy;
+  x = y = 1000000003UL; // 1e9 + 3
+  xy = 1000000006000000009UL; // x * y, precisely
+  // Even though the range analysis wrongly considers x*y to be xy - 9, there
+  // are no PointlessComparison false positives in these tests because alerts
+  // are suppressed when ulp() < 1, which roughly means that the number is
+  // larger than 2^53.
+  if (x * y < xy) {} // always false [NOT DETECTED]
+  if (x * y > xy) {} // always false [NOT DETECTED]
+}
+
+void mult_overflow() {
+  unsigned long x, y;
+  // The following two numbers multiply to 2^64 + 1, which is 1 when truncated
+  // to 64-bit unsigned.
+  x = 274177UL;
+  y = 67280421310721UL;
+  if (x * y == 1) {} // always true [BUG: reported as always false]
+
+  // This bug appears to be caused by
+  // `RangeAnalysisUtils::typeUpperBound(unsigned long)` having a result of
+  // 2**64 + 384, making the range analysis think that the multiplication can't
+  // overflow. The correct `typeUpperBound` would be 2**64 - 1, but we can't
+  // represent that with a QL float or int. We could make `typeUpperBound`
+  // exclusive instead of inclusive, but there is no exclusive upper bound for
+  // floats.
+}

cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.expected

@@ -41,6 +41,9 @@
 | PointlessComparison.c:372:6:372:16 | ... >= ... | Comparison is always true because ... >> ... >= 1. |
 | PointlessComparison.c:373:6:373:16 | ... >= ... | Comparison is always false because ... >> ... <= 1. |
 | PointlessComparison.c:383:6:383:17 | ... >= ... | Comparison is always false because ... & ... <= 2. |
+| PointlessComparison.c:388:10:388:21 | ... > ... | Comparison is always false because ... * ... <= 408. |
+| PointlessComparison.c:391:12:391:20 | ... < ... | Comparison is always false because ... * ... >= 6. |
+| PointlessComparison.c:414:7:414:16 | ... == ... | Comparison is always false because ... * ... >= 18446744073709552000. |
 | PointlessComparison.cpp:36:6:36:33 | ... >= ... | Comparison is always false because ... >> ... <= 9223372036854776000. |
 | PointlessComparison.cpp:41:6:41:29 | ... >= ... | Comparison is always false because ... >> ... <= 140737488355327.5. |
 | PointlessComparison.cpp:42:6:42:29 | ... >= ... | Comparison is always false because ... >> ... <= 140737488355327.5. |

cpp/ql/test/query-tests/Likely Bugs/Likely Typos/inconsistentLoopDirection/inconsistentLoopDirection.cpp

@@ -177,4 +177,43 @@ void FalseNegativeTestCases()
     for (int i = 100; i > 0; i += 2) {}
     // For comparison
     for (int i = 100; i > 0; i ++ ) {}  // BUG
-}
+}
+
+void IntendedOverflow(unsigned char p)
+{
+    const unsigned char m = 10;
+    unsigned char i;
+    signed char s;
+
+    for (i = 63; i < 64; i--) {} // GOOD (legitimate way to count down with an unsigned)
+    for (i = 63; i < 128; i--) {} // DUBIOUS (could still be a typo?)
+    for (i = 63; i < 255; i--) {} // GOOD
+
+    for (i = m - 1; i < m; i--) {} // GOOD
+    for (i = m - 2; i < m; i--) {} // DUBIOUS
+    for (i = m; i < m + 1; i--) {} // GOOD
+
+    for (s = 63; s < 64; s--) {} // BAD (signed numbers don't wrap at 0 / at all)
+    for (s = m + 1; s < m; s--) {} // BAD (never runs)
+
+    for (i = p - 1; i < p; i--) {} // GOOD
+    for (s = p - 1; s < p; s--) {} // BAD [NOT DETECTED]
+
+	{
+		int n;
+		
+		n = 64;
+		for (i = n - 1; i < n; i--) {} // GOOD
+		n = 64;
+		for (i = n - 1; i < 64; i--) {} // GOOD
+		n = 64;
+		for (i = 63; i < n; i--) {} // GOOD
+
+		n = 64;
+		for (s = n - 1; s < n; s--) {} // BAD [NOT DETECTED]
+		n = 64;
+		for (s = n - 1; s < 64; s--) {} // BAD
+		n = 64;
+		for (s = 63; s < n; s--) {} // BAD [NOT DETECTED]
+	}
+}

cpp/ql/test/query-tests/Likely Bugs/Likely Typos/inconsistentLoopDirection/inconsistentLoopDirection.expected

@@ -20,3 +20,6 @@
 | inconsistentLoopDirection.cpp:140:5:142:5 | for(...;...;...) ... | Ill-defined for-loop: a loop using variable "i" counts upward from a value (200), but the terminal condition is lower (0). |
 | inconsistentLoopDirection.cpp:175:5:175:36 | for(...;...;...) ... | Ill-defined for-loop: a loop using variable "i" counts downward from a value (0), but the terminal condition is higher (10). |
 | inconsistentLoopDirection.cpp:179:5:179:38 | for(...;...;...) ... | Ill-defined for-loop: a loop using variable "i" counts upward from a value (100), but the terminal condition is lower (0). |
+| inconsistentLoopDirection.cpp:196:5:196:32 | for(...;...;...) ... | Ill-defined for-loop: a loop using variable "s" counts downward from a value (63), but the terminal condition is higher (64). |
+| inconsistentLoopDirection.cpp:197:5:197:34 | for(...;...;...) ... | Ill-defined for-loop: a loop using variable "s" counts downward from a value (... + ...), but the terminal condition is always false. |
+| inconsistentLoopDirection.cpp:215:3:215:33 | for(...;...;...) ... | Ill-defined for-loop: a loop using variable "s" counts downward from a value (... - ...), but the terminal condition is higher (64). |

csharp/.vscode/extensions.json

@@ -0,0 +1,9 @@
+{
+    "recommendations": [
+        "github.vscode-codeql",
+        "ms-dotnettools.csharp",
+        "formulahendry.dotnet-test-explorer",
+        "hbenl.vscode-test-explorer"
+    ],
+    "unwantedRecommendations": []
+}

csharp/.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+    "dotnet-test-explorer.enableTelemetry": false,
+    "dotnet-test-explorer.testProjectPath": "**/*Tests.@(csproj|vbproj|fsproj)",
+    "dotnet-test-explorer.testArguments": "/property:GenerateTargetFrameworkAttribute=false",
+    "csharp.supressBuildAssetsNotification": true,
+    "csharp.suppressDotnetRestoreNotification": true
+}

csharp/.vscode/tasks.json

@@ -0,0 +1,53 @@
+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "dotnet build",
+            "command": "dotnet",
+            "type": "shell",
+            "args": [
+                "build",
+                // Ask dotnet build to generate full paths for file names.
+                "/property:GenerateFullPaths=true",
+                // Do not generate summary otherwise it leads to duplicate errors in Problems panel
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "group": "build",
+            "presentation": {
+                "reveal": "always"
+            },
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "dotnet rebuild",
+            "command": "dotnet",
+            "type": "shell",
+            "args": [
+                "build",
+                "--no-incremental",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "group": "build",
+            "presentation": {
+                "reveal": "always"
+            },
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "dotnet test",
+            "command": "dotnet",
+            "type": "shell",
+            "args": [
+                "test",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "group": "test",
+            "presentation": {
+                "reveal": "always"
+            },
+            "problemMatcher": "$msCompile"
+        }
+    ]
+}

csharp/codeql-extractor.yml

@@ -0,0 +1,18 @@
+name: "csharp"
+display_name: "C#"
+version: 1.22.1
+column_kind: "utf16"
+extra_env_vars:
+  DOTNET_GENERATE_ASPNET_CERTIFICATE: "false"
+  COR_ENABLE_PROFILING: "1"
+  COR_PROFILER: "{A3C70A64-7D41-4A94-A3F6-FD47D9259997}"
+  COR_PROFILER_PATH_64: "${env.CODEQL_EXTRACTOR_CSHARP_ROOT}/tools/${env.CODEQL_PLATFORM}/clrtracer64${env.CODEQL_PLATFORM_DLL_EXTENSION}"
+  CORECLR_ENABLE_PROFILING: "1"
+  CORECLR_PROFILER: "{A3C70A64-7D41-4A94-A3F6-FD47D9259997}"
+  CORECLR_PROFILER_PATH_64: "${env.CODEQL_EXTRACTOR_CSHARP_ROOT}/tools/${env.CODEQL_PLATFORM}/clrtracer64${env.CODEQL_PLATFORM_DLL_EXTENSION}"
+file_types:
+  - name: cs
+    display_name: C# sources
+    extensions:
+      - .cs
+legacy_qltest_extraction: true

csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ArrayCreation.cs

@@ -17,7 +17,7 @@ namespace Semmle.Extraction.CSharp.Entities.Expressions
 
         protected abstract ArrayTypeSyntax TypeSyntax { get; }
 
-        public abstract InitializerExpressionSyntax  Initializer { get;  }
+        public abstract InitializerExpressionSyntax Initializer { get; }
 
         protected override void PopulateExpression(TextWriter trapFile)
         {
@@ -48,7 +48,7 @@ namespace Semmle.Extraction.CSharp.Entities.Expressions
                             ExprKind.INT_LITERAL,
                             this,
                             child,
-                            false,
+                            true,
                             size.ToString());
 
                         new Expression(info);

csharp/ql/src/experimental/Security Features/Serialization/DataSetSerialization.qhelp

@@ -0,0 +1,23 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<overview>
+<p>The <code>DataSet</code> and <code>DataTable</code> types are legacy .NET components that you can use to represent data sets as managed objects.</p>
+
+<p>While <code>DataSet</code> and <code>DataTable</code> do impose default limitations on the types that are allowed to be present while deserializing XML payloads, <code>DataSet</code> and <code>DataTable</code> are in general not safe when populated with untrusted input.</p>
+
+<p>Please visit <a href="https://go.microsoft.com/fwlink/?linkid=2132227">DataSet and DataTable security guidance</a> for more details.</p>
+    
+</overview>
+<recommendation>
+
+<p>Please review the <a href="https://go.microsoft.com/fwlink/?linkid=2132227">DataSet and DataTable security guidance</a> before making use of these types for serialization.</p>
+
+</recommendation>
+<references>
+
+<li>Microsoft Docs<a href="https://go.microsoft.com/fwlink/?linkid=2132227">DataSet and DataTable security guidance</a>.</li>
+
+</references>
+</qhelp>

csharp/ql/src/experimental/Security Features/Serialization/DataSetSerialization.qll

@@ -0,0 +1,100 @@
+/**
+ * Provides classes for `DataSet` or `DataTable` deserialization queries.
+ *
+ * Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details.
+ */
+
+import csharp
+
+/**
+ * Abstract class that depends or inherits from `DataSet` or `DataTable` types.
+ */
+abstract class DataSetOrTableRelatedClass extends Class { }
+
+/**
+ * `DataSet`, `DataTable` types, or any types derived from them.
+ */
+class DataSetOrTable extends DataSetOrTableRelatedClass {
+  DataSetOrTable() {
+    this.getABaseType*().getQualifiedName() = "System.Data.DataTable" or
+    this.getABaseType*().getQualifiedName() = "System.Data.DataSet"
+  }
+}
+
+/**
+ * A Class that include a property or generic collection of type `DataSet` and `DataTable`
+ */
+class ClassWithDataSetOrTableMember extends DataSetOrTableRelatedClass {
+  ClassWithDataSetOrTableMember() {
+    this.getAMember().(AssignableMember).getType() instanceof DataSetOrTable
+    or
+    exists(Property p | p = this.getAProperty() |
+      p.getType() instanceof DataSetOrTable or
+      p.getType().(ConstructedGeneric).getATypeArgument() instanceof DataSetOrTable
+    )
+  }
+}
+
+/**
+ * Serializable types
+ */
+class SerializableClass extends Class {
+  SerializableClass() {
+    (
+      this.getABaseType*().getQualifiedName() = "System.Xml.Serialization.XmlSerializer" or
+      this.getABaseType*().getQualifiedName() = "System.Runtime.Serialization.ISerializable" or
+      this.getABaseType*().getQualifiedName() = "System.Runtime.Serialization.XmlObjectSerializer" or
+      this.getABaseType*().getQualifiedName() =
+        "System.Runtime.Serialization.ISerializationSurrogateProvider" or
+      this.getABaseType*().getQualifiedName() =
+        "System.Runtime.Serialization.XmlSerializableServices" or
+      this.getABaseType*().getQualifiedName() = "System.Xml.Serialization.IXmlSerializable"
+    )
+    or
+    exists(Attribute a | a = this.getAnAttribute() |
+      a.getType().getQualifiedName() = "System.SerializableAttribute"
+    )
+  }
+}
+
+/**
+ * Holds if the serializable class `c` has a property or field `m` that is of `DataSet` or `DataTable` related type
+ */
+predicate isClassUnsafeXmlSerializerImplementation(SerializableClass c, AssignableMember am) {
+  am = c.getAMember() and
+  am.getType() instanceof DataSetOrTableRelatedClass
+}
+
+/**
+ * Serializable class that has a property or field that is of `DataSet` or `DataTable` related type
+ */
+class UnsafeXmlSerializerImplementation extends SerializableClass {
+  UnsafeXmlSerializerImplementation() { isClassUnsafeXmlSerializerImplementation(this, _) }
+}
+
+/**
+ * Method that may be unsafe when used to deserialize DataSet and DataTable related types
+ */
+class UnsafeXmlReadMethod extends Method {
+  UnsafeXmlReadMethod() {
+    this.getQualifiedName() = "System.Data.DataTable.ReadXml"
+    or
+    this.getQualifiedName() = "System.Data.DataTable.ReadXmlSchema"
+    or
+    this.getQualifiedName() = "System.Data.DataSet.ReadXml"
+    or
+    this.getQualifiedName() = "System.Data.DataSet.ReadXmlSchema"
+    or
+    this.getName().matches("ReadXml%") and
+    exists(Class c | c.getAMethod() = this |
+      c.getABaseType*() instanceof DataSetOrTableRelatedClass
+    )
+  }
+}
+
+/**
+ * MethodCall that may be unsafe when used to deserialize DataSet and DataTable related types
+ */
+class UnsafeXmlReadMethodCall extends MethodCall {
+  UnsafeXmlReadMethodCall() { exists(UnsafeXmlReadMethod uxrm | uxrm.getACall() = this) }
+}

csharp/ql/src/experimental/Security Features/Serialization/DefiningDatasetRelatedType.qhelp

@@ -0,0 +1,5 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<include src="DataSetSerialization.qhelp" /></qhelp>

csharp/ql/src/experimental/Security Features/Serialization/DefiningDatasetRelatedType.ql

@@ -0,0 +1,16 @@
+/**
+ * @name Defining a class that inherits or has a property derived from the obsolete DataSet or DataTable types
+ * @description Defining a class that inherits or has a property derived from the obsolete DataSet or DataTable types may lead to the usage of dangerous functionality. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details.
+ * @kind problem
+ * @problem.severity warning
+ * @id cs/dataset-serialization/defining-dataset-related-type
+ * @tags security
+ */
+
+import csharp
+import DataSetSerialization
+
+from DataSetOrTableRelatedClass dstc
+where dstc.fromSource()
+select dstc,
+  "Defining a class that inherits or has a property derived from the obsolete DataSet or DataTable types. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details."

csharp/ql/src/experimental/Security Features/Serialization/DefiningPotentiallyUnsafeXmlSerialization.qhelp

@@ -0,0 +1,5 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<include src="DataSetSerialization.qhelp" /></qhelp>

csharp/ql/src/experimental/Security Features/Serialization/DefiningPotentiallyUnsafeXmlSerializer.ql

@@ -0,0 +1,20 @@
+/**
+ * @name Defining a potentially unsafe XML serializer
+ * @description Defining an XML serializable class that includes members that derive from DataSet or DataTable type may lead to a security problem. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details.
+ * @kind problem
+ * @problem.severity error
+ * @precision medium
+ * @id cs/dataset-serialization/defining-potentially-unsafe-xml-serializer
+ * @tags security
+ */
+
+import csharp
+import DataSetSerialization
+
+from UnsafeXmlSerializerImplementation c, Member m
+where
+  c.fromSource() and
+  isClassUnsafeXmlSerializerImplementation(c, m)
+select m,
+  "Defining an serializable class $@ that has member $@ of a type that is derived from DataSet or DataTable types and may lead to a security problem. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details.",
+  c, c.toString(), m, m.toString()

csharp/ql/src/experimental/Security Features/Serialization/UnsafeTypeUsedDataContractSerializer.qhelp

@@ -0,0 +1,5 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<include src="DataSetSerialization.qhelp" /></qhelp>

csharp/ql/src/experimental/Security Features/Serialization/UnsafeTypeUsedDataContractSerializer.ql

@@ -0,0 +1,43 @@
+/**
+ * @name Unsafe type is used in data contract serializer
+ * @description Unsafe type is used in data contract serializer. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details."
+ * @kind problem
+ * @problem.severity error
+ * @precision medium
+ * @id cs/dataset-serialization/unsafe-type-used-data-contract-serializer
+ * @tags security
+ */
+
+import csharp
+import DataSetSerialization
+
+predicate xmlSerializerConstructorArgument(Expr e) {
+  exists(ObjectCreation oc, Constructor c | e = oc.getArgument(0) |
+    c = oc.getTarget() and
+    c.getDeclaringType().getABaseType*().hasQualifiedName("System.Xml.Serialization.XmlSerializer")
+  )
+}
+
+predicate unsafeDataContractTypeCreation(Expr e) {
+  exists(MethodCall gt |
+    gt.getTarget().getName() = "GetType" and
+    e = gt and
+    gt.getQualifier().getType() instanceof DataSetOrTableRelatedClass
+  )
+  or
+  e.(TypeofExpr).getTypeAccess().getTarget() instanceof DataSetOrTableRelatedClass
+}
+
+class Conf extends DataFlow::Configuration {
+  Conf() { this = "FlowToDataSerializerConstructor" }
+
+  override predicate isSource(DataFlow::Node node) { unsafeDataContractTypeCreation(node.asExpr()) }
+
+  override predicate isSink(DataFlow::Node node) { xmlSerializerConstructorArgument(node.asExpr()) }
+}
+
+from Conf conf, DataFlow::Node source, DataFlow::Node sink
+where conf.hasFlow(source, sink)
+select sink,
+  "Unsafe type is used in data contract serializer. Make sure $@ comes from the trusted source.",
+  source, source.toString()

csharp/ql/src/experimental/Security Features/Serialization/XmlDeserializationWithDataSet.qhelp

@@ -0,0 +1,5 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<include src="DataSetSerialization.qhelp" /></qhelp>

csharp/ql/src/experimental/Security Features/Serialization/XmlDeserializationWithDataSet.ql

@@ -0,0 +1,16 @@
+/**
+ * @name XML deserialization with a type type derived from DataSet or DataTable
+ * @description Making an XML deserialization call with a type derived from DataSet or DataTable types and may lead to a security problem. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details."
+ * @kind problem
+ * @problem.severity error
+ * @precision medium
+ * @id cs/dataset-serialization/xml-deserialization-with-dataset
+ * @tags security
+ */
+
+import csharp
+import DataSetSerialization
+
+from UnsafeXmlReadMethodCall mc
+select mc,
+  "Making an XML deserialization call with a type derived from DataSet or DataTable types and may lead to a security problem. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details."

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl2.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl3.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl4.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl5.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImplCommon.qll

@@ -512,13 +512,19 @@ abstract class CallContext extends TCallContext {
   abstract predicate relevantFor(DataFlowCallable callable);
 }
 
-class CallContextAny extends CallContext, TAnyCallContext {
+abstract class CallContextNoCall extends CallContext { }
+
+class CallContextAny extends CallContextNoCall, TAnyCallContext {
   override string toString() { result = "CcAny" }
 
   override predicate relevantFor(DataFlowCallable callable) { any() }
 }
 
-abstract class CallContextCall extends CallContext { }
+abstract class CallContextCall extends CallContext {
+  /** Holds if this call context may be `call`. */
+  bindingset[call]
+  abstract predicate matchesCall(DataFlowCall call);
+}
 
 class CallContextSpecificCall extends CallContextCall, TSpecificCall {
   override string toString() {
@@ -529,6 +535,8 @@ class CallContextSpecificCall extends CallContextCall, TSpecificCall {
     recordDataFlowCallSite(getCall(), callable)
   }
 
+  override predicate matchesCall(DataFlowCall call) { call = this.getCall() }
+
   DataFlowCall getCall() { this = TSpecificCall(result) }
 }
 
@@ -538,9 +546,11 @@ class CallContextSomeCall extends CallContextCall, TSomeCall {
   override predicate relevantFor(DataFlowCallable callable) {
     exists(ParameterNode p | p.getEnclosingCallable() = callable)
   }
+
+  override predicate matchesCall(DataFlowCall call) { any() }
 }
 
-class CallContextReturn extends CallContext, TReturn {
+class CallContextReturn extends CallContextNoCall, TReturn {
   override string toString() {
     exists(DataFlowCall call | this = TReturn(_, call) | result = "CcReturn(" + call + ")")
   }

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -395,7 +395,7 @@ private predicate fieldOrPropertyStore(Expr e, Content c, Expr src, Expr q, bool
       f.isFieldLike() and
       f instanceof InstanceFieldOrProperty
       or
-      exists(AccessPath ap |
+      exists(LibraryFlow::AdjustedAccessPath ap |
         LibraryFlow::libraryFlowSummary(_, _, ap, _, _, _) and
         ap.contains(f.getContent())
       )
@@ -440,7 +440,7 @@ private predicate fieldOrPropertyRead(Expr e1, Content c, FieldOrPropertyRead e2
     ret.isFieldLike() and
     ret = e2.getTarget()
     or
-    exists(AccessPath ap, Property target |
+    exists(LibraryFlow::AdjustedAccessPath ap, Property target |
       LibraryFlow::libraryFlowSummary(_, _, _, _, ap, _) and
       ap.contains(ret.getContent()) and
       target.getGetter() = e2.(PropertyCall).getARuntimeTarget() and
@@ -569,8 +569,9 @@ private module Cached {
       )
     } or
     TLibraryCodeNode(
-      ControlFlow::Node callCfn, CallableFlowSource source, AccessPath sourceAp,
-      CallableFlowSink sink, AccessPath sinkAp, boolean preservesValue, LibraryCodeNodeState state
+      ControlFlow::Node callCfn, CallableFlowSource source, AdjustedAccessPath sourceAp,
+      CallableFlowSink sink, AdjustedAccessPath sinkAp, boolean preservesValue,
+      LibraryCodeNodeState state
     ) {
       libraryFlowSummary(callCfn.getElement(), source, sourceAp, sink, sinkAp, preservesValue) and
       (
@@ -1451,11 +1452,12 @@ import OutNodes
 module LibraryFlow {
   pragma[nomagic]
   private ValueOrRefType getPreciseSourceProperty0(
-    Call call, CallableFlowSource source, AccessPath sourceAp, Property p
+    Call call, CallableFlowSource source, AccessPath sourceAp, Property p, AccessPath sourceApTail
   ) {
     exists(LibraryTypeDataFlow ltdf, Property p0 |
       ltdf.callableFlow(source, sourceAp, _, _, call.getTarget().getSourceDeclaration(), _) and
-      sourceAp = AccessPath::property(p0) and
+      sourceAp.getHead().(PropertyContent).getProperty() = p0 and
+      sourceAp.getTail() = sourceApTail and
       overridesOrImplementsSourceDecl(p, p0) and
       result = source.getSourceType(call)
     )
@@ -1476,18 +1478,19 @@ module LibraryFlow {
    */
   pragma[nomagic]
   private Property getPreciseSourceProperty(
-    Call call, CallableFlowSource source, AccessPath sourceAp
+    Call call, CallableFlowSource source, AccessPath sourceAp, AccessPath sourceApTail
   ) {
-    getPreciseSourceProperty0(call, source, sourceAp, result).hasMember(result)
+    getPreciseSourceProperty0(call, source, sourceAp, result, sourceApTail).hasMember(result)
   }
 
   pragma[nomagic]
   private ValueOrRefType getPreciseSinkProperty0(
-    Call call, CallableFlowSink sink, AccessPath sinkAp, Property p
+    Call call, CallableFlowSink sink, AccessPath sinkAp, Property p, AccessPath sinkApTail
   ) {
     exists(LibraryTypeDataFlow ltdf, Property p0 |
       ltdf.callableFlow(_, _, sink, sinkAp, call.getTarget().getSourceDeclaration(), _) and
-      sinkAp = AccessPath::property(p0) and
+      sinkAp.getHead().(PropertyContent).getProperty() = p0 and
+      sinkAp.getTail() = sinkApTail and
       overridesOrImplementsSourceDecl(p, p0) and
       result = sink.getSinkType(call)
     )
@@ -1510,8 +1513,132 @@ module LibraryFlow {
    * from `IEnumerator<T>`.
    */
   pragma[nomagic]
-  private Property getPreciseSinkProperty(Call call, CallableFlowSink sink, AccessPath sinkAp) {
-    getPreciseSinkProperty0(call, sink, sinkAp, result).hasMember(result)
+  private Property getPreciseSinkProperty(
+    Call call, CallableFlowSink sink, AccessPath sinkAp, AccessPath sinkApTail
+  ) {
+    getPreciseSinkProperty0(call, sink, sinkAp, result, sinkApTail).hasMember(result)
+  }
+
+  predicate adjustSourceHead(
+    Call call, CallableFlowSource source, AccessPath sourceAp0, AccessPath sourceApTail,
+    PropertyContent p
+  ) {
+    overridesOrImplementsSourceDecl(p.getProperty(),
+      getPreciseSourceProperty(call, source, sourceAp0, sourceApTail).getSourceDeclaration())
+  }
+
+  predicate adjustSinkHead(
+    Call call, CallableFlowSink sink, AccessPath sinkAp0, AccessPath sinkApTail, PropertyContent p
+  ) {
+    p.getProperty() = getPreciseSinkProperty(call, sink, sinkAp0, sinkApTail).getSourceDeclaration()
+  }
+
+  private newtype TAdjustedAccessPath =
+    TOriginalAccessPath(AccessPath ap) or
+    THeadAdjustedAccessPath(PropertyContent head, AccessPath tail) {
+      adjustSourceHead(_, _, _, tail, head)
+      or
+      adjustSinkHead(_, _, _, tail, head)
+    }
+
+  /**
+   * An access path used in a library-code flow-summary, where the head of the path
+   * may have been adjusted. For example, in
+   *
+   * ```csharp
+   * var list = new List<string>();
+   * list.Add("taint");
+   * var enumerator = list.getEnumerator();
+   * ```
+   *
+   * the step from `list` to `list.getEnumerator()`, which may be modeled as a
+   * read of a collection element followed by a store into the `Current`
+   * property, can be strengthened to be a store into the `Current` property
+   * from `List<T>.Enumerator`, rather than the generic `Current` property
+   * from `IEnumerator<T>`.
+   */
+  abstract class AdjustedAccessPath extends TAdjustedAccessPath {
+    /** Gets the head of this access path, if any. */
+    abstract Content getHead();
+
+    /** Gets the tail of this access path, if any. */
+    abstract AdjustedAccessPath getTail();
+
+    /** Gets the length of this access path. */
+    abstract int length();
+
+    /** Gets the access path obtained by dropping the first `i` elements, if any. */
+    abstract AdjustedAccessPath drop(int i);
+
+    /** Holds if this access path contains content `c`. */
+    predicate contains(Content c) { c = this.drop(_).getHead() }
+
+    /** Gets a textual representation of this access path. */
+    string toString() {
+      exists(Content head, AdjustedAccessPath tail |
+        head = this.getHead() and
+        tail = this.getTail() and
+        if tail.length() = 0 then result = head.toString() else result = head + ", " + tail
+      )
+      or
+      this.length() = 0 and
+      result = "<empty>"
+    }
+  }
+
+  private class OriginalAccessPath extends AdjustedAccessPath, TOriginalAccessPath {
+    private AccessPath ap;
+
+    OriginalAccessPath() { this = TOriginalAccessPath(ap) }
+
+    override Content getHead() { result = ap.getHead() }
+
+    override AdjustedAccessPath getTail() { result = TOriginalAccessPath(ap.getTail()) }
+
+    override int length() { result = ap.length() }
+
+    override AdjustedAccessPath drop(int i) { result = TOriginalAccessPath(ap.drop(i)) }
+  }
+
+  private class HeadAdjustedAccessPath extends AdjustedAccessPath, THeadAdjustedAccessPath {
+    private PropertyContent head;
+    private AccessPath tail;
+
+    HeadAdjustedAccessPath() { this = THeadAdjustedAccessPath(head, tail) }
+
+    override Content getHead() { result = head }
+
+    override AdjustedAccessPath getTail() { result = TOriginalAccessPath(tail) }
+
+    override int length() { result = 1 + tail.length() }
+
+    override AdjustedAccessPath drop(int i) {
+      i = 0 and result = this
+      or
+      result = TOriginalAccessPath(tail.drop(i - 1))
+    }
+  }
+
+  module AdjustedAccessPath {
+    AdjustedAccessPath empty() { result.length() = 0 }
+
+    AdjustedAccessPath singleton(Content c) { result.getHead() = c and result.length() = 1 }
+  }
+
+  pragma[nomagic]
+  private predicate callableFlow(
+    CallableFlowSource source, AccessPath sourceAp, boolean adjustSourceAp, CallableFlowSink sink,
+    AccessPath sinkAp, boolean adjustSinkAp, SourceDeclarationCallable c, boolean preservesValue
+  ) {
+    any(LibraryTypeDataFlow ltdf).callableFlow(source, sourceAp, sink, sinkAp, c, preservesValue) and
+    (
+      if sourceAp.getHead() instanceof PropertyContent
+      then adjustSourceAp = true
+      else adjustSourceAp = false
+    ) and
+    if sinkAp.getHead() instanceof PropertyContent
+    then adjustSinkAp = true
+    else adjustSinkAp = false
   }
 
   /**
@@ -1524,33 +1651,38 @@ module LibraryFlow {
    */
   pragma[nomagic]
   predicate libraryFlowSummary(
-    Call call, CallableFlowSource source, AccessPath sourceAp, CallableFlowSink sink,
-    AccessPath sinkAp, boolean preservesValue
+    Call call, CallableFlowSource source, AdjustedAccessPath sourceAp, CallableFlowSink sink,
+    AdjustedAccessPath sinkAp, boolean preservesValue
   ) {
-    exists(LibraryTypeDataFlow ltdf, SourceDeclarationCallable c |
-      c = call.getTarget().getSourceDeclaration()
-    |
-      ltdf.callableFlow(source, sink, c, preservesValue) and
-      sourceAp = AccessPath::empty() and
-      sinkAp = AccessPath::empty()
+    exists(SourceDeclarationCallable c | c = call.getTarget().getSourceDeclaration() |
+      any(LibraryTypeDataFlow ltdf).callableFlow(source, sink, c, preservesValue) and
+      sourceAp = TOriginalAccessPath(AccessPath::empty()) and
+      sinkAp = TOriginalAccessPath(AccessPath::empty())
       or
-      exists(AccessPath sourceAp0, AccessPath sinkAp0 |
-        ltdf.callableFlow(source, sourceAp0, sink, sinkAp0, c, preservesValue) and
+      exists(
+        AccessPath sourceAp0, boolean adjustSourceAp, AccessPath sinkAp0, boolean adjustSinkAp
+      |
+        callableFlow(source, sourceAp0, adjustSourceAp, sink, sinkAp0, adjustSinkAp, c,
+          preservesValue) and
         (
-          not sourceAp0 = AccessPath::property(_) and
-          sourceAp = sourceAp0
+          adjustSourceAp = false and
+          sourceAp = TOriginalAccessPath(sourceAp0)
           or
-          exists(Property p |
-            overridesOrImplementsSourceDecl(p,
-              getPreciseSourceProperty(call, source, sourceAp0).getSourceDeclaration()) and
-            sourceAp = AccessPath::property(p)
+          adjustSourceAp = true and
+          exists(PropertyContent p, AccessPath sourceApTail |
+            adjustSourceHead(call, source, sourceAp0, sourceApTail, p) and
+            sourceAp = THeadAdjustedAccessPath(p, sourceApTail)
           )
         ) and
         (
-          not sinkAp0 = AccessPath::property(_) and
-          sinkAp = sinkAp0
+          adjustSinkAp = false and
+          sinkAp = TOriginalAccessPath(sinkAp0)
           or
-          sinkAp = AccessPath::property(getPreciseSinkProperty(call, sink, sinkAp0))
+          adjustSinkAp = true and
+          exists(PropertyContent p, AccessPath sinkApTail |
+            adjustSinkHead(call, sink, sinkAp0, sinkApTail, p) and
+            sinkAp = THeadAdjustedAccessPath(p, sinkApTail)
+          )
         )
       )
     )
@@ -1606,8 +1738,8 @@ module LibraryFlow {
   }
 
   newtype TLibraryCodeNodeState =
-    TLibraryCodeNodeAfterReadState(AccessPath ap) { ap.length() > 0 } or
-    TLibraryCodeNodeBeforeStoreState(AccessPath ap) { ap.length() > 0 }
+    TLibraryCodeNodeAfterReadState(AdjustedAccessPath ap) { ap.length() > 0 } or
+    TLibraryCodeNodeBeforeStoreState(AdjustedAccessPath ap) { ap.length() > 0 }
 
   /**
    * A state used to break up (complex) flow summaries for library code into atomic
@@ -1626,12 +1758,12 @@ module LibraryFlow {
    */
   class LibraryCodeNodeState extends TLibraryCodeNodeState {
     string toString() {
-      exists(AccessPath ap |
+      exists(AdjustedAccessPath ap |
         this = TLibraryCodeNodeAfterReadState(ap) and
         result = "after read: " + ap
       )
       or
-      exists(AccessPath ap |
+      exists(AdjustedAccessPath ap |
         this = TLibraryCodeNodeBeforeStoreState(ap) and
         result = "before store: " + ap
       )
@@ -1639,12 +1771,12 @@ module LibraryFlow {
 
     /** Holds if this state represents the state after the last read. */
     predicate isLastReadState() {
-      this = TLibraryCodeNodeAfterReadState(any(AccessPath ap | ap.length() = 1))
+      this = TLibraryCodeNodeAfterReadState(AdjustedAccessPath::singleton(_))
     }
 
     /** Holds if this state represents the state before the first store. */
     predicate isFirstStoreState() {
-      this = TLibraryCodeNodeBeforeStoreState(any(AccessPath ap | ap.length() = 1))
+      this = TLibraryCodeNodeBeforeStoreState(AdjustedAccessPath::singleton(_))
     }
   }
 
@@ -1726,21 +1858,21 @@ module LibraryFlow {
    */
   predicate localStepLibrary(Node pred, Node succ, boolean preservesValue) {
     exists(
-      ControlFlow::Node callCfn, CallableFlowSource source, AccessPath sourceAp,
-      CallableFlowSink sink, AccessPath sinkAp
+      ControlFlow::Node callCfn, CallableFlowSource source, AdjustedAccessPath sourceAp,
+      CallableFlowSink sink, AdjustedAccessPath sinkAp
     |
       libraryFlowSummary(callCfn.getElement(), source, sourceAp, sink, sinkAp, preservesValue)
     |
       // Simple flow summary without reads or stores
-      sourceAp = AccessPath::empty() and
-      sinkAp = AccessPath::empty() and
+      sourceAp = AdjustedAccessPath::empty() and
+      sinkAp = AdjustedAccessPath::empty() and
       entry(pred, callCfn, source) and
       exit(succ, callCfn, sink)
       or
       // Entry step for a complex summary with no reads and (1) multiple stores, or
       // (2) at least one store and non-value-preservation
       exists(LibraryCodeNodeState succState |
-        sourceAp.length() = 0 and
+        sourceAp = AdjustedAccessPath::empty() and
         entry(pred, callCfn, source) and
         succState.isFirstStoreState() and
         succ = TLibraryCodeNode(callCfn, source, sourceAp, sink, sinkAp, preservesValue, succState)
@@ -1749,7 +1881,7 @@ module LibraryFlow {
       // Exit step for a complex summary with no stores and (1) multiple reads, or
       // (2) at least one read and non-value-preservation
       exists(LibraryCodeNodeState predState |
-        sinkAp.length() = 0 and
+        sinkAp = AdjustedAccessPath::empty() and
         predState.isLastReadState() and
         pred = TLibraryCodeNode(callCfn, source, sourceAp, sink, sinkAp, preservesValue, predState) and
         exit(succ, callCfn, sink)
@@ -1758,8 +1890,8 @@ module LibraryFlow {
     or
     // Internal step for complex flow summaries with both reads and writes
     exists(
-      ControlFlow::Node callCfn, CallableFlowSource source, AccessPath sourceAp,
-      CallableFlowSink sink, AccessPath sinkAp, LibraryCodeNodeState predState,
+      ControlFlow::Node callCfn, CallableFlowSource source, AdjustedAccessPath sourceAp,
+      CallableFlowSink sink, AdjustedAccessPath sinkAp, LibraryCodeNodeState predState,
       LibraryCodeNodeState succState
     |
       predState.isLastReadState() and
@@ -1775,8 +1907,8 @@ module LibraryFlow {
    */
   predicate setterLibrary(Node pred, Content c, Node succ, boolean preservesValue) {
     exists(ControlFlow::Node callCfn, CallableFlowSource source, CallableFlowSink sink |
-      libraryFlowSummary(callCfn.getElement(), source, AccessPath::empty(), sink,
-        AccessPath::singleton(c), preservesValue)
+      libraryFlowSummary(callCfn.getElement(), source, AdjustedAccessPath::empty(), sink,
+        AdjustedAccessPath::singleton(c), preservesValue)
     |
       entry(pred, callCfn, source) and
       exit(succ, callCfn, sink)
@@ -1790,9 +1922,9 @@ module LibraryFlow {
   predicate storeStepLibrary(Node pred, Content c, Node succ) {
     // Complex flow summary
     exists(
-      ControlFlow::Node callCfn, CallableFlowSource source, AccessPath sourceAp,
-      CallableFlowSink sink, AccessPath sinkAp, boolean preservesValue,
-      LibraryCodeNodeState predState, AccessPath ap
+      ControlFlow::Node callCfn, CallableFlowSource source, AdjustedAccessPath sourceAp,
+      CallableFlowSink sink, AdjustedAccessPath sinkAp, boolean preservesValue,
+      LibraryCodeNodeState predState, AdjustedAccessPath ap
     |
       predState = TLibraryCodeNodeBeforeStoreState(ap) and
       pred = TLibraryCodeNode(callCfn, source, sourceAp, sink, sinkAp, preservesValue, predState) and
@@ -1800,7 +1932,8 @@ module LibraryFlow {
     |
       // More stores needed
       exists(LibraryCodeNodeState succState |
-        succState = TLibraryCodeNodeBeforeStoreState(any(AccessPath succAp | succAp.getTail() = ap)) and
+        succState =
+          TLibraryCodeNodeBeforeStoreState(any(AdjustedAccessPath succAp | succAp.getTail() = ap)) and
         succ = TLibraryCodeNode(callCfn, source, sourceAp, sink, sinkAp, preservesValue, succState)
       )
       or
@@ -1819,8 +1952,8 @@ module LibraryFlow {
    */
   predicate getterLibrary(Node pred, Content c, Node succ, boolean preservesValue) {
     exists(ControlFlow::Node callCfn, CallableFlowSource source, CallableFlowSink sink |
-      libraryFlowSummary(callCfn.getElement(), source, AccessPath::singleton(c), sink,
-        AccessPath::empty(), preservesValue) and
+      libraryFlowSummary(callCfn.getElement(), source, AdjustedAccessPath::singleton(c), sink,
+        AdjustedAccessPath::empty(), preservesValue) and
       entry(pred, callCfn, source) and
       exit(succ, callCfn, sink)
     )
@@ -1833,9 +1966,9 @@ module LibraryFlow {
   predicate readStepLibrary(Node pred, Content c, Node succ) {
     // Complex flow summary
     exists(
-      ControlFlow::Node callCfn, CallableFlowSource source, AccessPath sourceAp,
-      CallableFlowSink sink, AccessPath sinkAp, boolean preservesValue,
-      LibraryCodeNodeState succState, AccessPath ap
+      ControlFlow::Node callCfn, CallableFlowSource source, AdjustedAccessPath sourceAp,
+      CallableFlowSink sink, AdjustedAccessPath sinkAp, boolean preservesValue,
+      LibraryCodeNodeState succState, AdjustedAccessPath ap
     |
       succState = TLibraryCodeNodeAfterReadState(ap) and
       succ = TLibraryCodeNode(callCfn, source, sourceAp, sink, sinkAp, preservesValue, succState) and
@@ -1846,7 +1979,7 @@ module LibraryFlow {
       entry(pred, callCfn, source)
       or
       // Subsequent reads
-      exists(LibraryCodeNodeState predState, AccessPath predAp |
+      exists(LibraryCodeNodeState predState, AdjustedAccessPath predAp |
         predState = TLibraryCodeNodeAfterReadState(predAp) and
         predAp.getTail() = ap and
         pred = TLibraryCodeNode(callCfn, source, sourceAp, sink, sinkAp, preservesValue, predState)
@@ -1886,9 +2019,9 @@ private DataFlowType getContentType(Content c) {
 class LibraryCodeNode extends NodeImpl, TLibraryCodeNode {
   private ControlFlow::Node callCfn;
   private CallableFlowSource source;
-  private AccessPath sourceAp;
+  private LibraryFlow::AdjustedAccessPath sourceAp;
   private CallableFlowSink sink;
-  private AccessPath sinkAp;
+  private LibraryFlow::AdjustedAccessPath sinkAp;
   private boolean preservesValue;
   private LibraryFlow::LibraryCodeNodeState state;
 
@@ -1899,7 +2032,7 @@ class LibraryCodeNode extends NodeImpl, TLibraryCodeNode {
   override Callable getEnclosingCallableImpl() { result = callCfn.getEnclosingCallable() }
 
   override DataFlowType getDataFlowType() {
-    exists(AccessPath ap |
+    exists(LibraryFlow::AdjustedAccessPath ap |
       state = LibraryFlow::TLibraryCodeNodeAfterReadState(ap) and
       if sinkAp.length() = 0 and state.isLastReadState() and preservesValue = true
       then result = Gvn::getGlobalValueNumber(sink.getSinkType(callCfn.getElement()))

csharp/ql/src/semmle/code/csharp/frameworks/system/Xml.qll

@@ -2,7 +2,7 @@
 
 import csharp
 private import semmle.code.csharp.frameworks.System
-private import semmle.code.csharp.dataflow.DataFlow2
+private import semmle.code.csharp.dataflow.DataFlow3
 
 /** The `System.Xml` namespace. */
 class SystemXmlNamespace extends Namespace {
@@ -163,7 +163,7 @@ class XmlReaderSettingsCreation extends ObjectCreation {
   }
 }
 
-private class SettingsDataFlowConfig extends DataFlow2::Configuration {
+private class SettingsDataFlowConfig extends DataFlow3::Configuration {
   SettingsDataFlowConfig() { this = "SettingsDataFlowConfig" }
 
   override predicate isSource(DataFlow::Node source) {

csharp/ql/test/experimental/Security Features/Serialization/DefiningDatasetRelatedType.expected

@@ -0,0 +1,2 @@
+| test0.cs:13:18:13:43 | DerivesFromDeprecatedType1 | Defining a class that inherits or has a property derived from the obsolete DataSet or DataTable types. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details. |
+| test0.cs:59:18:59:38 | AttributeSerializer01 | Defining a class that inherits or has a property derived from the obsolete DataSet or DataTable types. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details. |

csharp/ql/test/experimental/Security Features/Serialization/DefiningDatasetRelatedType.qlref

@@ -0,0 +1 @@
+experimental/Security Features/Serialization/DefiningDatasetRelatedType.ql

csharp/ql/test/experimental/Security Features/Serialization/DefiningPotentiallyUnsafeXmlSerializer.expected

@@ -0,0 +1,2 @@
+| test0.cs:15:24:15:32 | MyDataSet | Defining an serializable class $@ that has member $@ of a type that is derived from DataSet or DataTable types and may lead to a security problem. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details. | test0.cs:13:18:13:43 | DerivesFromDeprecatedType1 | DerivesFromDeprecatedType1 | test0.cs:15:24:15:32 | MyDataSet | MyDataSet |
+| test0.cs:61:25:61:33 | MyDataSet | Defining an serializable class $@ that has member $@ of a type that is derived from DataSet or DataTable types and may lead to a security problem. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details. | test0.cs:59:18:59:38 | AttributeSerializer01 | AttributeSerializer01 | test0.cs:61:25:61:33 | MyDataSet | MyDataSet |

csharp/ql/test/experimental/Security Features/Serialization/DefiningPotentiallyUnsafeXmlSerializer.qlref

@@ -0,0 +1 @@
+experimental/Security Features/Serialization/DefiningPotentiallyUnsafeXmlSerializer.ql

csharp/ql/test/experimental/Security Features/Serialization/UnsafeTypeUsedDataContractSerializer.expected

@@ -0,0 +1,2 @@
+| test0.cs:95:49:95:63 | typeof(...) | Unsafe type is used in data contract serializer. Make sure $@ comes from the trusted source. | test0.cs:95:49:95:63 | typeof(...) | typeof(...) |
+| test0.cs:96:49:96:77 | typeof(...) | Unsafe type is used in data contract serializer. Make sure $@ comes from the trusted source. | test0.cs:96:49:96:77 | typeof(...) | typeof(...) |

csharp/ql/test/experimental/Security Features/Serialization/UnsafeTypeUsedDataContractSerializer.qlref

@@ -0,0 +1 @@
+experimental/Security Features/Serialization/UnsafeTypeUsedDataContractSerializer.ql

csharp/ql/test/experimental/Security Features/Serialization/XmlDeserializationWithDataSet.expected

@@ -0,0 +1 @@
+| test0.cs:88:17:88:46 | call to method ReadXmlSchema | Making an XML deserialization call with a type derived from DataSet or DataTable types and may lead to a security problem. Please visit https://go.microsoft.com/fwlink/?linkid=2132227 for details. |

csharp/ql/test/experimental/Security Features/Serialization/XmlDeserializationWithDataSet.qlref

@@ -0,0 +1 @@
+experimental/Security Features/Serialization/XmlDeserializationWithDataSet.ql

csharp/ql/test/experimental/Security Features/Serialization/test0.cs

@@ -0,0 +1,101 @@
+// semmle-extractor-options: /r:System.Data.Common.dll /r:System.Runtime.WindowsRuntime.dll /r:System.Xml.XmlSerializer.dll /r:System.Runtime.Serialization.Xml.dll /r:System.Runtime.Serialization.Xml.dll /r:System.Collections.dll /r:System.Private.Xml.dll /r:System.Private.DataContractSerialization.dll /r:System.Runtime.Extensions.dll /r:System.ComponentModel.TypeConverter.dll /r:System.Xml.ReaderWriter.dll /r:System.IO.FileSystem.dll
+
+using System;
+using System.Data;
+using System.IO;
+using System.Xml.Serialization;
+using System.Runtime.Serialization;
+using System.Xml;
+using System.Collections.Generic;
+
+namespace DataSetSerializationTest
+{
+    public class DerivesFromDeprecatedType1 : XmlSerializer // warning:DefiningDatasetRelatedType.ql
+    {
+        public DataSet MyDataSet { get; set; }  // bug:DefiningPotentiallyUnsafeXmlSerializer.ql
+
+        public DerivesFromDeprecatedType1()
+        {
+        }
+    }
+
+    /*  
+     *  TODO: I cannot use DataContract on a QL unit test
+     *  
+    [DataContract(Name = "Customer", Namespace = "http://www.contoso.com")]
+    public class PatternDataContractSerializer : XmlObjectSerializer
+    {
+        [DataMember()]
+        public DataSet MyDataSet { get; set; }
+        [DataMember()]
+        public DataTable MyDataTable { get; set; }
+
+        PatternDataContractSerializer() { }
+        private ExtensionDataObject extensionData_Value;
+        public ExtensionDataObject ExtensionData
+        {
+            get
+            {
+                return extensionData_Value;
+            }
+            set
+            {
+                extensionData_Value = value;
+            }
+        }
+
+        public override void WriteObject(System.IO.Stream stream, object graph) { }
+        public override void WriteObjectContent(System.Xml.XmlDictionaryWriter writer, object graph) { }
+        public override bool IsStartObject(System.Xml.XmlDictionaryReader reader) { return false; }
+        public override void WriteStartObject(System.Xml.XmlDictionaryWriter writer, object graph) { }
+        public override void WriteEndObject(System.Xml.XmlWriter writer) { }
+        public override void WriteEndObject(XmlDictionaryWriter writer) { }
+        public override object ReadObject(System.IO.Stream stream) { return null; }
+        public override object ReadObject(XmlDictionaryReader reader, bool b) { return null; }
+    }
+    */
+
+    [Serializable()]
+    public class AttributeSerializer01  // warning:DefiningDatasetRelatedType.ql
+    {
+        private DataSet MyDataSet;  // bug:DefiningPotentiallyUnsafeXmlSerializer.ql
+
+        AttributeSerializer01()
+        {
+        }
+    }
+
+    class Program
+    {
+        static string GetSerializedDataSet(DataSet dataSet)
+        {
+            DataTable dataTable = new DataTable("MyTable");
+            dataTable.Columns.Add("FirstName", typeof(string));
+            dataTable.Columns.Add("LastName", typeof(string));
+            dataTable.Columns.Add("Age", typeof(int));
+
+            StringWriter writer = new StringWriter();
+            dataSet.WriteXml(writer, XmlWriteMode.DiffGram);
+            return writer.ToString();
+        }
+
+        static void datatable_readxmlschema_01(string fileName)
+        {
+            using (FileStream fs = File.OpenRead(fileName))
+            {
+                DataTable newTable = new DataTable();
+                System.Xml.XmlTextReader reader = new System.Xml.XmlTextReader(fs);
+                newTable.ReadXmlSchema(reader); //bug:XmlDeserializationWithDataSet.ql
+            }
+        }
+
+        static void Main(string[] args)
+        {
+
+            XmlSerializer x = new XmlSerializer(typeof(DataSet));   // bug:UnsafeTypeUsedDataContractSerializer.ql
+            XmlSerializer y = new XmlSerializer(typeof(AttributeSerializer01)); //bug:UnsafeTypeUsedDataContractSerializer.ql
+
+            Console.WriteLine("Hello World!");
+        }
+    }
+}

csharp/ql/test/library-tests/expressions/ArrayCreation11.expected

@@ -0,0 +1,3 @@
+| expressions.cs:168:27:168:44 | array creation of type Object[] | expressions.cs:168:27:168:44 | 1 | true |
+| expressions.cs:409:23:409:65 | array creation of type Int32[,] | expressions.cs:409:23:409:65 | 3 | true |
+| expressions.cs:409:23:409:65 | array creation of type Int32[,] | expressions.cs:409:23:409:65 | 3 | true |

csharp/ql/test/library-tests/expressions/ArrayCreation11.ql

@@ -0,0 +1,13 @@
+/**
+ * @name Test for array creations
+ */
+
+import csharp
+
+private boolean isImplicit(Expr expr) {
+  if expr.isImplicit() then result = true else result = false
+}
+
+from ArrayCreation ac, Expr expr
+where ac.isImplicitlySized() and not ac.isImplicitlyTyped() and expr = ac.getALengthArgument()
+select ac, expr, isImplicit(expr)

csharp/tools/autobuild.cmd

@@ -0,0 +1,9 @@
+@echo off
+SETLOCAL EnableDelayedExpansion
+
+rem The autobuilder is already being traced
+set CODEQL_AUTOBUILDER_CSHARP_NO_INDEXING=true
+
+type NUL && "%CODEQL_EXTRACTOR_CSHARP_ROOT%/tools/%CODEQL_PLATFORM%/Semmle.Autobuild.CSharp.exe" || exit /b %ERRORLEVEL%
+
+ENDLOCAL

csharp/tools/autobuild.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+set -eu
+
+if [ "$CODEQL_PLATFORM" != "linux64" ] && [ "$CODEQL_PLATFORM" != "osx64" ] ; then
+    echo "Automatic build detection for $CODEQL_PLATFORM is not implemented."
+    exit 1
+fi
+
+# The autobuilder is already being traced
+CODEQL_AUTOBUILDER_CSHARP_NO_INDEXING="true"
+export CODEQL_AUTOBUILDER_CSHARP_NO_INDEXING
+
+"$CODEQL_EXTRACTOR_CSHARP_ROOT/tools/$CODEQL_PLATFORM/Semmle.Autobuild.CSharp" || exit $?

csharp/tools/linux64/compiler-tracing.spec

@@ -0,0 +1,9 @@
+**/mcs.exe:
+**/csc.exe:
+  invoke ${config_dir}/Semmle.Extraction.CSharp.Driver
+  prepend --compiler
+  prepend "${compiler}"
+  prepend --cil
+**/mono*:
+**/dotnet:
+  invoke ${config_dir}/extract-csharp.sh

csharp/tools/linux64/extract-csharp.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+echo extract-csharp.sh: Called with arguments: "$@"
+
+extractor="$CODEQL_EXTRACTOR_CSHARP_ROOT/tools/$CODEQL_PLATFORM/Semmle.Extraction.CSharp.Driver"
+
+for i in "$@"
+do
+  shift
+  if [[ `basename -- "$i"` =~ csc.exe|mcs.exe|csc.dll ]]
+  then
+    echo extract-csharp.sh: exec $extractor --cil $@
+    exec "$extractor" --compiler $i --cil $@
+  fi
+done
+
+echo extract-csharp.sh: Not a compiler invocation

csharp/tools/osx64/compiler-tracing.spec

@@ -0,0 +1,14 @@
+**/mcs.exe:
+**/csc.exe:
+  invoke ${config_dir}/Semmle.Extraction.CSharp.Driver
+  prepend --compiler
+  prepend "${compiler}"
+  prepend --cil
+**/mono*:
+**/dotnet:
+  invoke ${config_dir}/extract-csharp.sh
+/usr/bin/codesign:
+  replace yes
+  invoke /usr/bin/env
+  prepend /usr/bin/codesign
+  trace no