JS: Improve comments in FunctionBodyFeatures.qll

This reverts commit ff1d0cc4c7.

.codeqlmanifest.json

@@ -4,13 +4,24 @@
         "*/ql/lib/qlpack.yml",
         "*/ql/test/qlpack.yml",
         "*/ql/examples/qlpack.yml",
-        "*/upgrades/qlpack.yml",
         "cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/tainted/qlpack.yml",
         "javascript/ql/experimental/adaptivethreatmodeling/lib/qlpack.yml",
         "javascript/ql/experimental/adaptivethreatmodeling/src/qlpack.yml",
+        "csharp/ql/campaigns/Solorigate/lib/qlpack.yml",
+        "csharp/ql/campaigns/Solorigate/src/qlpack.yml",
+        "csharp/ql/campaigns/Solorigate/test/qlpack.yml",
         "misc/legacy-support/*/qlpack.yml",
         "misc/suite-helpers/qlpack.yml",
+        "ruby/extractor-pack/codeql-extractor.yml",
         "ruby/ql/consistency-queries/qlpack.yml",
-        "ruby/extractor-pack/codeql-extractor.yml"
-   ]
-}
+        "ql/ql/consistency-queries/qlpack.yml",
+        "ql/extractor-pack/codeql-extractor.yml"
+    ],
+    "versionPolicies": {
+      "default": {
+        "requireChangeNotes": true,
+        "committedPrereleaseSuffix": "dev",
+        "committedVersion": "nextPatchRelease"
+      }
+    }
+}

.github/labeler.yml

@@ -26,3 +26,6 @@ documentation:
   - "**/*.qhelp"
   - "**/*.md"
   - docs/**/*
+
+"QL-for-QL": 
+  - ql/**/*

.github/workflows/check-change-note.yml

@@ -7,6 +7,7 @@ on:
       - "*/ql/src/**/*.ql"
       - "*/ql/src/**/*.qll"
       - "!**/experimental/**"
+      - "!ql/**"
 
 jobs:
   check-change-note:

.github/workflows/ql-for-ql-build.yml

@@ -0,0 +1,192 @@
+name: Run QL for QL
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  queries:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Find codeql
+        id: find-codeql
+        uses: github/codeql-action/init@erik-krogh/ql
+        with:
+          languages: javascript # does not matter
+      - name: Get CodeQL version
+        id: get-codeql-version
+        run: |
+          echo "::set-output name=version::$("${CODEQL}" --version | head -n 1 | rev | cut -d " " -f 1 | rev)"
+        shell: bash
+        env:
+          CODEQL: ${{ steps.find-codeql.outputs.codeql-path }}
+      - name: Cache queries
+        id: cache-queries
+        uses: actions/cache@v2
+        with:
+          path: ${{ runner.temp }}/query-pack.zip
+          key: queries-${{ hashFiles('ql/**/*.ql*') }}-${{ hashFiles('ql/ql/src/ql.dbscheme*') }}-${{ steps.get-codeql-version.outputs.version }}
+      - name: Build query pack
+        if: steps.cache-queries.outputs.cache-hit != 'true'
+        run: |
+          cd ql/ql/src
+          "${CODEQL}" pack create
+          cd .codeql/pack/codeql/ql-all/0.0.0
+          zip "${PACKZIP}" -r .
+        env:
+          CODEQL: ${{ steps.find-codeql.outputs.codeql-path }}
+          PACKZIP: ${{ runner.temp }}/query-pack.zip
+      - name: Upload query pack
+        uses: actions/upload-artifact@v2
+        with:
+          name: query-pack-zip
+          path: ${{ runner.temp }}/query-pack.zip
+
+  extractors:
+    strategy:
+      fail-fast: false
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Cache entire extractor
+        id: cache-extractor
+        uses: actions/cache@v2
+        with:
+          path: |
+            ql/target/release/ql-autobuilder
+            ql/target/release/ql-autobuilder.exe
+            ql/target/release/ql-extractor
+            ql/target/release/ql-extractor.exe
+          key: ${{ runner.os }}-extractor-${{ hashFiles('ql/**/Cargo.lock') }}-${{ hashFiles('ql/**/*.rs') }}
+      - name: Cache cargo
+        if: steps.cache-extractor.outputs.cache-hit != 'true'
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            ql/target
+          key: ${{ runner.os }}-rust-cargo-${{ hashFiles('ql/**/Cargo.lock') }}
+      - name: Check formatting
+        if: steps.cache-extractor.outputs.cache-hit != 'true'
+        run: cd ql; cargo fmt --all -- --check
+      - name: Build
+        if: steps.cache-extractor.outputs.cache-hit != 'true'
+        run: cd ql; cargo build --verbose
+      - name: Run tests
+        if: steps.cache-extractor.outputs.cache-hit != 'true'
+        run: cd ql; cargo test --verbose
+      - name: Release build
+        if: steps.cache-extractor.outputs.cache-hit != 'true'
+        run: cd ql; cargo build --release
+      - name: Generate dbscheme
+        if: steps.cache-extractor.outputs.cache-hit != 'true'
+        run: ql/target/release/ql-generator --dbscheme ql/ql/src/ql.dbscheme --library ql/ql/src/codeql_ql/ast/internal/TreeSitter.qll
+      - uses: actions/upload-artifact@v2
+        with:
+          name: extractor-ubuntu-latest
+          path: |
+            ql/target/release/ql-autobuilder
+            ql/target/release/ql-autobuilder.exe
+            ql/target/release/ql-extractor
+            ql/target/release/ql-extractor.exe
+          retention-days: 1
+  package:
+    runs-on: ubuntu-latest
+
+    needs:
+      - extractors
+      - queries
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/download-artifact@v2
+        with:
+          name: query-pack-zip
+          path: query-pack-zip
+      - uses: actions/download-artifact@v2
+        with:
+          name: extractor-ubuntu-latest
+          path: linux64
+      - run: |
+          unzip query-pack-zip/*.zip -d pack
+          cp -r ql/codeql-extractor.yml ql/tools ql/ql/src/ql.dbscheme.stats pack/
+          mkdir -p pack/tools/linux64
+          if [[ -f linux64/ql-autobuilder ]]; then
+            cp linux64/ql-autobuilder pack/tools/linux64/autobuilder
+            chmod +x pack/tools/linux64/autobuilder
+          fi
+          if [[ -f linux64/ql-extractor ]]; then
+            cp linux64/ql-extractor pack/tools/linux64/extractor
+            chmod +x pack/tools/linux64/extractor
+          fi
+          cd pack
+          zip -rq ../codeql-ql.zip .
+      - uses: actions/upload-artifact@v2
+        with:
+          name: codeql-ql-pack
+          path: codeql-ql.zip
+          retention-days: 1
+  analyze:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        folder: [cpp, csharp, java, javascript, python, ql, ruby]
+
+    needs:
+      - package
+
+    steps:
+      - name: Download pack
+        uses: actions/download-artifact@v2
+        with:
+          name: codeql-ql-pack
+          path: ${{ runner.temp }}/codeql-ql-pack-artifact
+
+      - name: Prepare pack
+        run: |
+          unzip "${PACK_ARTIFACT}/*.zip" -d "${PACK}"
+        env:
+          PACK_ARTIFACT: ${{ runner.temp }}/codeql-ql-pack-artifact
+          PACK: ${{ runner.temp }}/pack
+      - name: Hack codeql-action options
+        run: |
+          JSON=$(jq -nc --arg pack "${PACK}" '.resolve.queries=["--search-path", $pack] | .resolve.extractor=["--search-path", $pack] | .database.init=["--search-path", $pack]')
+          echo "CODEQL_ACTION_EXTRA_OPTIONS=${JSON}" >> ${GITHUB_ENV}
+        env:
+          PACK: ${{ runner.temp }}/pack
+
+      - name: Checkout repository
+        uses: actions/checkout@v2
+      - name: Create CodeQL config file
+        run: |
+          echo "paths:" > ${CONF}
+          echo "  - ${FOLDER}" >> ${CONF}
+          echo "paths-ignore:" >> ${CONF}
+          echo "  - ql/ql/test" >> ${CONF}
+          echo "Config file: "
+          cat ${CONF}
+        env: 
+          CONF: ./ql-for-ql-config.yml
+          FOLDER: ${{ matrix.folder }}
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@erik-krogh/ql
+        with:
+          languages: ql
+          db-location: ${{ runner.temp }}/db
+          config-file: ./ql-for-ql-config.yml
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@erik-krogh/ql
+        with: 
+          category: "ql-for-ql-${{ matrix.folder }}"
+

.github/workflows/ql-for-ql-dataset_measure.yml

@@ -0,0 +1,84 @@
+name: Collect database stats for QL for QL
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - ql/ql/src/ql.dbscheme
+  pull_request:
+    branches: [main]
+    paths:
+      - ql/ql/src/ql.dbscheme
+  workflow_dispatch:
+
+jobs:
+  measure:
+    env:
+      CODEQL_THREADS: 4 # TODO: remove this once it's set by the CLI
+    strategy:
+      matrix:
+        repo: 
+          - github/codeql
+          - github/codeql-go
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Find codeql
+        id: find-codeql
+        uses: github/codeql-action/init@erik-krogh/ql
+        with:
+          languages: javascript # does not matter
+      - uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            ql/target
+          key: ${{ runner.os }}-qltest-cargo-${{ hashFiles('**/Cargo.lock') }}
+      - name: Build Extractor
+        run: cd ql; env "PATH=$PATH:`dirname ${CODEQL}`" ./create-extractor-pack.sh
+        env:
+          CODEQL: ${{ steps.find-codeql.outputs.codeql-path }}
+      - name: Checkout ${{ matrix.repo }}
+        uses: actions/checkout@v2
+        with:
+          repository: ${{ matrix.repo }}
+          path: ${{ github.workspace }}/repo
+      - name: Create database
+        run: |
+          "${CODEQL}" database create \
+            --search-path "ql/extractor-pack" \
+            --threads 4 \
+            --language ql --source-root "${{ github.workspace }}/repo" \
+            "${{ runner.temp }}/database"
+        env:
+          CODEQL: ${{ steps.find-codeql.outputs.codeql-path }}
+      - name: Measure database
+        run: |
+          mkdir -p "stats/${{ matrix.repo }}"
+          "${CODEQL}" dataset measure --threads 4 --output "stats/${{ matrix.repo }}/stats.xml" "${{ runner.temp }}/database/db-ql"
+        env:
+          CODEQL: ${{ steps.find-codeql.outputs.codeql-path }}
+      - uses: actions/upload-artifact@v2
+        with:
+          name: measurements
+          path: stats
+          retention-days: 1
+
+  merge:
+    runs-on: ubuntu-latest
+    needs: measure
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/download-artifact@v2
+        with:
+          name: measurements
+          path: stats
+      - run: |
+          python -m pip install --user lxml
+          find stats -name 'stats.xml' -print0 | sort -z | xargs -0 python ql/scripts/merge_stats.py --output ql/ql/src/ql.dbscheme.stats --normalise ql_tokeninfo
+      - uses: actions/upload-artifact@v2
+        with:
+          name: ql.dbscheme.stats
+          path: ql/ql/src/ql.dbscheme.stats

.github/workflows/ql-for-ql-tests.yml

@@ -0,0 +1,52 @@
+name: Run QL for QL Tests
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - "ql/**"
+  pull_request:
+    branches: [main]
+    paths:
+      - "ql/**"
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  qltest:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Find codeql
+        id: find-codeql
+        uses: github/codeql-action/init@erik-krogh/ql
+        with:
+          languages: javascript # does not matter
+      - uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            ql/target
+          key: ${{ runner.os }}-qltest-cargo-${{ hashFiles('**/Cargo.lock') }}
+      - name: Build extractor
+        run: |
+          cd ql;
+          codeqlpath=$(dirname ${{ steps.find-codeql.outputs.codeql-path }});
+          env "PATH=$PATH:$codeqlpath" ./create-extractor-pack.sh
+      - name: Run QL tests
+        run: | 
+          "${CODEQL}" test run --check-databases --check-unused-labels --check-repeated-labels --check-redefined-labels --check-use-before-definition --search-path "${{ github.workspace }}/ql/extractor-pack" --consistency-queries ql/ql/consistency-queries ql/ql/test
+        env:
+          CODEQL: ${{ steps.find-codeql.outputs.codeql-path }}
+      - name: Check QL formatting
+        run: | 
+          find ql/ql "(" -name "*.ql" -or -name "*.qll" ")" -print0 | xargs -0 "${CODEQL}" query format --check-only
+        env:
+          CODEQL: ${{ steps.find-codeql.outputs.codeql-path }}
+      - name: Check QL compilation
+        run: | 
+          "${CODEQL}" query compile --check-only --threads=4 --warnings=error --search-path "${{ github.workspace }}/ql/extractor-pack" "ql/ql/src" "ql/ql/examples"
+        env:
+          CODEQL: ${{ steps.find-codeql.outputs.codeql-path }}

.github/workflows/ruby-dataset-measure.yml

@@ -24,7 +24,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        repo: [rails/rails, discourse/discourse, spree/spree]
+        repo: [rails/rails, discourse/discourse, spree/spree, ruby/ruby]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2

CODEOWNERS

@@ -25,3 +25,6 @@
 /docs/codeql-for-visual-studio-code/ @github/codeql-vscode-reviewers
 /docs/ql-language-reference/ @github/codeql-frontend-reviewers
 /docs/query-*-style-guide.md @github/codeql-analysis-reviewers
+
+# QL for QL reviewers
+/ql/ @erik-krogh @tausbn

README.md

@@ -1,11 +1,11 @@
 # CodeQL
 
-This open source repository contains the standard CodeQL libraries and queries that power [LGTM](https://lgtm.com) and the other CodeQL products that [GitHub](https://github.com) makes available to its customers worldwide. For the queries, libraries, and extractor that power Go analysis, visit the [CodeQL for Go repository](https://github.com/github/codeql-go).
+This open source repository contains the standard CodeQL libraries and queries that power [GitHub Advanced Security](https://github.com/features/security/code) and the other application security products that [GitHub](https://github.com/features/security/) makes available to its customers worldwide. For the queries, libraries, and extractor that power Go analysis, visit the [CodeQL for Go repository](https://github.com/github/codeql-go).
 
 ## How do I learn CodeQL and run queries?
 
 There is [extensive documentation](https://codeql.github.com/docs/) on getting started with writing CodeQL.
-You can use the [interactive query console](https://lgtm.com/help/lgtm/using-query-console) on LGTM.com or the [CodeQL for Visual Studio Code](https://codeql.github.com/docs/codeql-for-visual-studio-code/) extension to try out your queries on any open source project that's currently being analyzed.
+You can use the [CodeQL for Visual Studio Code](https://codeql.github.com/docs/codeql-for-visual-studio-code/) extension or the [interactive query console](https://lgtm.com/help/lgtm/using-query-console) on LGTM.com (Semmle Legacy product) to try out your queries on any open source project that's currently being analyzed.
 
 ## Contributing
 
@@ -13,7 +13,7 @@ We welcome contributions to our standard library and standard checks. Do you hav
 
 ## License
 
-The code in this repository is licensed under the [MIT License](LICENSE) by [GitHub](https://github.com).
+The code in this repository is licensed under the [MIT License](LICENSE) by [GitHub](https://github.com). The use of CodeQL on open source code is licensed under specific [Terms & Conditions](https://securitylab.github.com/tools/codeql/license/) UNLESS you have a commercial license in place. If you'd like to use CodeQL with a commercial codebase, please [contact us](https://github.com/enterprise/contact) for further help.
 
 ## Visual Studio Code integration
 

config/identical-files.json

@@ -452,9 +452,15 @@
     "ruby/ql/lib/codeql/ruby/dataflow/internal/SsaImplCommon.qll",
     "cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaImplCommon.qll"
   ],
-  "CryptoAlgorithms Python/JS": [
+  "CryptoAlgorithms Python/JS/Ruby": [
     "javascript/ql/lib/semmle/javascript/security/CryptoAlgorithms.qll",
-    "python/ql/lib/semmle/python/concepts/CryptoAlgorithms.qll"
+    "python/ql/lib/semmle/python/concepts/CryptoAlgorithms.qll",
+    "ruby/ql/lib/codeql/ruby/security/CryptoAlgorithms.qll"
+  ],
+  "CryptoAlgorithmNames Python/JS/Ruby": [
+    "javascript/ql/lib/semmle/javascript/security/internal/CryptoAlgorithmNames.qll",
+    "python/ql/lib/semmle/python/concepts/internal/CryptoAlgorithmNames.qll",
+    "ruby/ql/lib/codeql/ruby/security/internal/CryptoAlgorithmNames.qll"
   ],
   "SensitiveDataHeuristics Python/JS": [
     "javascript/ql/lib/semmle/javascript/security/internal/SensitiveDataHeuristics.qll",

cpp/autobuilder/Semmle.Autobuild.Cpp/Semmle.Autobuild.Cpp.csproj

@@ -17,7 +17,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Build" Version="16.9.0" />
+    <PackageReference Include="Microsoft.Build" Version="16.11.0" />
   </ItemGroup>
 
   <ItemGroup>

cpp/old-change-notes/2021-10-07-cleartext-transmission.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The "Cleartext transmission of sensitive information" (`cpp/cleartext-transmission`) query has been improved, reducing the number of false positive results when encryption is present.

cpp/ql/lib/CHANGELOG.md

@@ -0,0 +1,9 @@
+## 0.0.5
+
+## 0.0.4
+
+### New Features
+
+* The QL library `semmle.code.cpp.commons.Exclusions` now contains a predicate
+  `isFromSystemMacroDefinition` for identifying code that originates from a
+  macro outside the project being analyzed.

cpp/ql/lib/DefaultOptions.qll

@@ -73,7 +73,7 @@ class Options extends string {
    *   __assume(0);
    * ```
    * (note that in this case if the hint is wrong and the expression is reached at
-   * runtime, the program's behaviour is undefined)
+   * runtime, the program's behavior is undefined)
    */
   predicate exprExits(Expr e) {
     e.(AssumeExpr).getChild(0).(CompileTimeConstantInt).getIntValue() = 0 or

cpp/ql/lib/Options.qll

@@ -50,7 +50,7 @@ class CustomOptions extends Options {
    *   __assume(0);
    * ```
    * (note that in this case if the hint is wrong and the expression is reached at
-   * runtime, the program's behaviour is undefined)
+   * runtime, the program's behavior is undefined)
    */
   override predicate exprExits(Expr e) { Options.super.exprExits(e) }
 

cpp/ql/lib/change-notes/released/0.0.4.md

@@ -1,4 +1,7 @@
-lgtm,codescanning
+## 0.0.4
+
+### New Features
+
 * The QL library `semmle.code.cpp.commons.Exclusions` now contains a predicate
   `isFromSystemMacroDefinition` for identifying code that originates from a
   macro outside the project being analyzed.

cpp/ql/lib/change-notes/released/0.0.5.md

@@ -0,0 +1 @@
+## 0.0.5

cpp/ql/lib/codeql-pack.release.yml

@@ -0,0 +1,2 @@
+---
+lastReleaseVersion: 0.0.5

cpp/ql/lib/experimental/semmle/code/cpp/models/interfaces/SimpleRangeAnalysisDefinition.qll

@@ -37,7 +37,7 @@ abstract class SimpleRangeAnalysisDefinition extends RangeSsaDefinition {
    * dependencies. Without this information, range analysis might work for
    * simple cases but will go into infinite loops on complex code.
    *
-   * For example, when modelling the definition by reference in a call to an
+   * For example, when modeling the definition by reference in a call to an
    * overloaded `operator=`, written as `v = e`, the definition of `(this, v)`
    * depends on `e`.
    */

cpp/ql/lib/experimental/semmle/code/cpp/rangeanalysis/InBoundsPointerDeref.qll

@@ -5,7 +5,7 @@
  * `Instruction` level), and then using the array length analysis and the range
  * analysis together to prove that some of these pointer dereferences are safe.
  *
- * The analysis is soundy, i.e. it is sound if no undefined behaviour is present
+ * The analysis is soundy, i.e. it is sound if no undefined behavior is present
  * in the program.
  * Furthermore, it crucially depends on the soundiness of the range analysis and
  * the array length analysis.

cpp/ql/lib/qlpack.yml

@@ -1,7 +1,7 @@
 name: codeql/cpp-all
-version: 0.0.2
+version: 0.0.6-dev
+groups: cpp
 dbscheme: semmlecode.cpp.dbscheme
 extractor: cpp
 library: true
-dependencies:
-  codeql/cpp-upgrades: 0.0.2
+upgrades: upgrades

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

@@ -9,6 +9,83 @@ import semmle.code.cpp.models.interfaces.FormattingFunction
 private import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
 private import semmle.code.cpp.rangeanalysis.RangeAnalysisUtils
 
+private newtype TBufferWriteEstimationReason =
+  TNoSpecifiedEstimateReason() or
+  TTypeBoundsAnalysis() or
+  TValueFlowAnalysis()
+
+/**
+ * A reason for a specific buffer write size estimate.
+ */
+abstract class BufferWriteEstimationReason extends TBufferWriteEstimationReason {
+  /**
+   * Returns the name of the concrete class.
+   */
+  abstract string toString();
+
+  /**
+   * Returns a human readable representation of this reason.
+   */
+  abstract string getDescription();
+
+  /**
+   * Combine estimate reasons. Used to give a reason for the size of a format string
+   * conversion given reasons coming from its individual specifiers.
+   */
+  abstract BufferWriteEstimationReason combineWith(BufferWriteEstimationReason other);
+}
+
+/**
+ * No particular reason given. This is currently used for backward compatibility so that
+ * classes derived from BufferWrite and overriding `getMaxData/0` still work with the
+ * queries as intended.
+ */
+class NoSpecifiedEstimateReason extends BufferWriteEstimationReason, TNoSpecifiedEstimateReason {
+  override string toString() { result = "NoSpecifiedEstimateReason" }
+
+  override string getDescription() { result = "no reason specified" }
+
+  override BufferWriteEstimationReason combineWith(BufferWriteEstimationReason other) {
+    // this reason should not be used in format specifiers, so it should not be combined
+    // with other reasons
+    none()
+  }
+}
+
+/**
+ * The estimation comes from rough bounds just based on the type (e.g.
+ * `0 <= x < 2^32` for an unsigned 32 bit integer).
+ */
+class TypeBoundsAnalysis extends BufferWriteEstimationReason, TTypeBoundsAnalysis {
+  override string toString() { result = "TypeBoundsAnalysis" }
+
+  override string getDescription() { result = "based on type bounds" }
+
+  override BufferWriteEstimationReason combineWith(BufferWriteEstimationReason other) {
+    other != TNoSpecifiedEstimateReason() and result = TTypeBoundsAnalysis()
+  }
+}
+
+/**
+ * The estimation comes from non trivial bounds found via actual flow analysis.
+ * For example
+ * ```
+ * unsigned u = x;
+ * if (u < 1000) {
+ *    //...  <- estimation done here based on u
+ * }
+ * ```
+ */
+class ValueFlowAnalysis extends BufferWriteEstimationReason, TValueFlowAnalysis {
+  override string toString() { result = "ValueFlowAnalysis" }
+
+  override string getDescription() { result = "based on flow analysis of value bounds" }
+
+  override BufferWriteEstimationReason combineWith(BufferWriteEstimationReason other) {
+    other != TNoSpecifiedEstimateReason() and result = other
+  }
+}
+
 class PrintfFormatAttribute extends FormatAttribute {
   PrintfFormatAttribute() { this.getArchetype() = ["printf", "__printf__"] }
 }
@@ -990,7 +1067,14 @@ class FormatLiteral extends Literal {
    * conversion specifier of this format string; has no result if this cannot
    * be determined.
    */
-  int getMaxConvertedLength(int n) {
+  int getMaxConvertedLength(int n) { result = max(getMaxConvertedLength(n, _)) }
+
+  /**
+   * Gets the maximum length of the string that can be produced by the nth
+   * conversion specifier of this format string, specifying the estimation reason;
+   * has no result if this cannot be determined.
+   */
+  int getMaxConvertedLength(int n, BufferWriteEstimationReason reason) {
     exists(int len |
       (
         (
@@ -1002,10 +1086,12 @@ class FormatLiteral extends Literal {
       ) and
       (
         this.getConversionChar(n) = "%" and
-        len = 1
+        len = 1 and
+        reason = TValueFlowAnalysis()
         or
         this.getConversionChar(n).toLowerCase() = "c" and
-        len = 1 // e.g. 'a'
+        len = 1 and
+        reason = TValueFlowAnalysis() // e.g. 'a'
         or
         this.getConversionChar(n).toLowerCase() = "f" and
         exists(int dot, int afterdot |
@@ -1019,7 +1105,8 @@ class FormatLiteral extends Literal {
             afterdot = 6
           ) and
           len = 1 + 309 + dot + afterdot
-        ) // e.g. -1e308="-100000"...
+        ) and
+        reason = TTypeBoundsAnalysis() // e.g. -1e308="-100000"...
         or
         this.getConversionChar(n).toLowerCase() = "e" and
         exists(int dot, int afterdot |
@@ -1033,7 +1120,8 @@ class FormatLiteral extends Literal {
             afterdot = 6
           ) and
           len = 1 + 1 + dot + afterdot + 1 + 1 + 3
-        ) // -1e308="-1.000000e+308"
+        ) and
+        reason = TTypeBoundsAnalysis() // -1e308="-1.000000e+308"
         or
         this.getConversionChar(n).toLowerCase() = "g" and
         exists(int dot, int afterdot |
@@ -1056,67 +1144,80 @@ class FormatLiteral extends Literal {
           //       (e.g. 123456, 0.000123456 are just OK)
           //       so case %f can be at most P characters + 4 zeroes, sign, dot = P + 6
           len = (afterdot.maximum(1) + 6).maximum(1 + 1 + dot + afterdot + 1 + 1 + 3)
-        ) // (e.g. "-1.59203e-319")
+        ) and
+        reason = TTypeBoundsAnalysis() // (e.g. "-1.59203e-319")
         or
         this.getConversionChar(n).toLowerCase() = ["d", "i"] and
         // e.g. -2^31 = "-2147483648"
-        len =
-          min(float cand |
-            // The first case handles length sub-specifiers
-            // Subtract one in the exponent because one bit is for the sign.
-            // Add 1 to account for the possible sign in the output.
-            cand = 1 + lengthInBase10(2.pow(this.getIntegralDisplayType(n).getSize() * 8 - 1))
-            or
-            // The second case uses range analysis to deduce a length that's shorter than the length
-            // of the number -2^31.
-            exists(Expr arg, float lower, float upper |
-              arg = this.getUse().getConversionArgument(n) and
-              lower = lowerBound(arg.getFullyConverted()) and
-              upper = upperBound(arg.getFullyConverted())
-            |
-              cand =
-                max(int cand0 |
-                  // Include the sign bit in the length if it can be negative
-                  (
-                    if lower < 0
-                    then cand0 = 1 + lengthInBase10(lower.abs())
-                    else cand0 = lengthInBase10(lower)
-                  )
-                  or
-                  (
-                    if upper < 0
-                    then cand0 = 1 + lengthInBase10(upper.abs())
-                    else cand0 = lengthInBase10(upper)
-                  )
+        exists(float typeBasedBound, float valueBasedBound |
+          // The first case handles length sub-specifiers
+          // Subtract one in the exponent because one bit is for the sign.
+          // Add 1 to account for the possible sign in the output.
+          typeBasedBound =
+            1 + lengthInBase10(2.pow(this.getIntegralDisplayType(n).getSize() * 8 - 1)) and
+          // The second case uses range analysis to deduce a length that's shorter than the length
+          // of the number -2^31.
+          exists(Expr arg, float lower, float upper, float typeLower, float typeUpper |
+            arg = this.getUse().getConversionArgument(n) and
+            lower = lowerBound(arg.getFullyConverted()) and
+            upper = upperBound(arg.getFullyConverted()) and
+            typeLower = exprMinVal(arg.getFullyConverted()) and
+            typeUpper = exprMaxVal(arg.getFullyConverted())
+          |
+            valueBasedBound =
+              max(int cand |
+                // Include the sign bit in the length if it can be negative
+                (
+                  if lower < 0
+                  then cand = 1 + lengthInBase10(lower.abs())
+                  else cand = lengthInBase10(lower)
                 )
+                or
+                (
+                  if upper < 0
+                  then cand = 1 + lengthInBase10(upper.abs())
+                  else cand = lengthInBase10(upper)
+                )
+              ) and
+            (
+              if lower > typeLower or upper < typeUpper
+              then reason = TValueFlowAnalysis()
+              else reason = TTypeBoundsAnalysis()
             )
-          )
+          ) and
+          len = valueBasedBound.minimum(typeBasedBound)
+        )
         or
         this.getConversionChar(n).toLowerCase() = "u" and
         // e.g. 2^32 - 1 = "4294967295"
-        len =
-          min(float cand |
-            // The first case handles length sub-specifiers
-            cand = 2.pow(this.getIntegralDisplayType(n).getSize() * 8)
-            or
-            // The second case uses range analysis to deduce a length that's shorter than
-            // the length of the number 2^31 - 1.
-            exists(Expr arg, float lower |
-              arg = this.getUse().getConversionArgument(n) and
-              lower = lowerBound(arg.getFullyConverted())
-            |
-              cand =
-                max(float cand0 |
+        exists(float typeBasedBound, float valueBasedBound |
+          // The first case handles length sub-specifiers
+          typeBasedBound = lengthInBase10(2.pow(this.getIntegralDisplayType(n).getSize() * 8) - 1) and
+          // The second case uses range analysis to deduce a length that's shorter than
+          // the length of the number 2^31 - 1.
+          exists(Expr arg, float lower, float upper, float typeLower, float typeUpper |
+            arg = this.getUse().getConversionArgument(n) and
+            lower = lowerBound(arg.getFullyConverted()) and
+            upper = upperBound(arg.getFullyConverted()) and
+            typeLower = exprMinVal(arg.getFullyConverted()) and
+            typeUpper = exprMaxVal(arg.getFullyConverted())
+          |
+            valueBasedBound =
+              lengthInBase10(max(float cand |
                   // If lower can be negative we use `(unsigned)-1` as the candidate value.
                   lower < 0 and
-                  cand0 = 2.pow(any(IntType t | t.isUnsigned()).getSize() * 8)
+                  cand = 2.pow(any(IntType t | t.isUnsigned()).getSize() * 8)
                   or
-                  cand0 = upperBound(arg.getFullyConverted())
-                )
+                  cand = upper
+                )) and
+            (
+              if lower > typeLower or upper < typeUpper
+              then reason = TValueFlowAnalysis()
+              else reason = TTypeBoundsAnalysis()
             )
-          |
-            lengthInBase10(cand)
-          )
+          ) and
+          len = valueBasedBound.minimum(typeBasedBound)
+        )
         or
         this.getConversionChar(n).toLowerCase() = "x" and
         // e.g. "12345678"
@@ -1135,7 +1236,8 @@ class FormatLiteral extends Literal {
           (
             if this.hasAlternateFlag(n) then len = 2 + baseLen else len = baseLen // "0x"
           )
-        )
+        ) and
+        reason = TTypeBoundsAnalysis()
         or
         this.getConversionChar(n).toLowerCase() = "p" and
         exists(PointerType ptrType, int baseLen |
@@ -1144,7 +1246,8 @@ class FormatLiteral extends Literal {
           (
             if this.hasAlternateFlag(n) then len = 2 + baseLen else len = baseLen // "0x"
           )
-        )
+        ) and
+        reason = TValueFlowAnalysis()
         or
         this.getConversionChar(n).toLowerCase() = "o" and
         // e.g. 2^32 - 1 = "37777777777"
@@ -1163,14 +1266,16 @@ class FormatLiteral extends Literal {
           (
             if this.hasAlternateFlag(n) then len = 1 + baseLen else len = baseLen // "0"
           )
-        )
+        ) and
+        reason = TTypeBoundsAnalysis()
         or
         this.getConversionChar(n).toLowerCase() = "s" and
         len =
           min(int v |
             v = this.getPrecision(n) or
             v = this.getUse().getFormatArgument(n).(AnalysedString).getMaxLength() - 1 // (don't count null terminator)
-          )
+          ) and
+        reason = TValueFlowAnalysis()
       )
     )
   }
@@ -1182,10 +1287,19 @@ class FormatLiteral extends Literal {
    * determining whether a buffer overflow is caused by long float to string
    * conversions.
    */
-  int getMaxConvertedLengthLimited(int n) {
+  int getMaxConvertedLengthLimited(int n) { result = max(getMaxConvertedLengthLimited(n, _)) }
+
+  /**
+   * Gets the maximum length of the string that can be produced by the nth
+   * conversion specifier of this format string, specifying the reason for the
+   * estimation, except that float to string conversions are assumed to be 8
+   * characters.  This is helpful for determining whether a buffer overflow is
+   * caused by long float to string conversions.
+   */
+  int getMaxConvertedLengthLimited(int n, BufferWriteEstimationReason reason) {
     if this.getConversionChar(n).toLowerCase() = "f"
-    then result = this.getMaxConvertedLength(n).minimum(8)
-    else result = this.getMaxConvertedLength(n)
+    then result = this.getMaxConvertedLength(n, reason).minimum(8)
+    else result = this.getMaxConvertedLength(n, reason)
   }
 
   /**
@@ -1225,29 +1339,35 @@ class FormatLiteral extends Literal {
     )
   }
 
-  private int getMaxConvertedLengthAfter(int n) {
+  private int getMaxConvertedLengthAfter(int n, BufferWriteEstimationReason reason) {
     if n = this.getNumConvSpec()
-    then result = this.getConstantSuffix().length() + 1
+    then result = this.getConstantSuffix().length() + 1 and reason = TValueFlowAnalysis()
     else
-      result =
-        this.getConstantPart(n).length() + this.getMaxConvertedLength(n) +
-          this.getMaxConvertedLengthAfter(n + 1)
+      exists(BufferWriteEstimationReason headReason, BufferWriteEstimationReason tailReason |
+        result =
+          this.getConstantPart(n).length() + this.getMaxConvertedLength(n, headReason) +
+            this.getMaxConvertedLengthAfter(n + 1, tailReason) and
+        reason = headReason.combineWith(tailReason)
+      )
   }
 
-  private int getMaxConvertedLengthAfterLimited(int n) {
+  private int getMaxConvertedLengthAfterLimited(int n, BufferWriteEstimationReason reason) {
     if n = this.getNumConvSpec()
-    then result = this.getConstantSuffix().length() + 1
+    then result = this.getConstantSuffix().length() + 1 and reason = TValueFlowAnalysis()
     else
-      result =
-        this.getConstantPart(n).length() + this.getMaxConvertedLengthLimited(n) +
-          this.getMaxConvertedLengthAfterLimited(n + 1)
+      exists(BufferWriteEstimationReason headReason, BufferWriteEstimationReason tailReason |
+        result =
+          this.getConstantPart(n).length() + this.getMaxConvertedLengthLimited(n, headReason) +
+            this.getMaxConvertedLengthAfterLimited(n + 1, tailReason) and
+        reason = headReason.combineWith(tailReason)
+      )
   }
 
   /**
    * Gets the maximum length of the string that can be produced by this format
    * string.  Has no result if this cannot be determined.
    */
-  int getMaxConvertedLength() { result = this.getMaxConvertedLengthAfter(0) }
+  int getMaxConvertedLength() { result = this.getMaxConvertedLengthAfter(0, _) }
 
   /**
    * Gets the maximum length of the string that can be produced by this format
@@ -1255,5 +1375,24 @@ class FormatLiteral extends Literal {
    * characters.  This is helpful for determining whether a buffer overflow
    * is caused by long float to string conversions.
    */
-  int getMaxConvertedLengthLimited() { result = this.getMaxConvertedLengthAfterLimited(0) }
+  int getMaxConvertedLengthLimited() { result = this.getMaxConvertedLengthAfterLimited(0, _) }
+
+  /**
+   * Gets the maximum length of the string that can be produced by this format
+   * string, specifying the reason for the estimate. Has no result if no estimate
+   * can be found.
+   */
+  int getMaxConvertedLengthWithReason(BufferWriteEstimationReason reason) {
+    result = this.getMaxConvertedLengthAfter(0, reason)
+  }
+
+  /**
+   * Gets the maximum length of the string that can be produced by this format
+   * string, specifying the reason for the estimate, except that float to string
+   * conversions are assumed to be 8 characters.  This is helpful for determining
+   * whether a buffer overflow is caused by long float to string conversions.
+   */
+  int getMaxConvertedLengthLimitedWithReason(BufferWriteEstimationReason reason) {
+    result = this.getMaxConvertedLengthAfterLimited(0, reason)
+  }
 }

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

@@ -153,9 +153,11 @@ library class SSAHelper extends int {
    * Modern Compiler Implementation by Andrew Appel.
    */
   private predicate frontier_phi_node(StackVariable v, BasicBlock b) {
-    exists(BasicBlock x | dominanceFrontier(x, b) and ssa_defn_rec(v, x)) and
+    exists(BasicBlock x |
+      dominanceFrontier(x, b) and ssa_defn_rec(pragma[only_bind_into](v), pragma[only_bind_into](x))
+    ) and
     /* We can also eliminate those nodes where the variable is not live on any incoming edge */
-    live_at_start_of_bb(v, b)
+    live_at_start_of_bb(pragma[only_bind_into](v), b)
   }
 
   private predicate ssa_defn_rec(StackVariable v, BasicBlock b) {

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

@@ -626,9 +626,9 @@ library class ExprEvaluator extends int {
       // All assignments must have the same int value
       result =
         unique(Expr value |
-          value = v.getAnAssignedValue() and not ignoreVariableAssignment(e, v, value)
+          value = v.getAnAssignedValue() and not this.ignoreVariableAssignment(e, v, value)
         |
-          getValueInternalNonSubExpr(value)
+          this.getValueInternalNonSubExpr(value)
         )
     )
   }

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

@@ -1,4 +1,6 @@
 private import cpp
+private import semmle.code.cpp.dataflow.internal.DataFlowPrivate
+private import semmle.code.cpp.dataflow.internal.DataFlowUtil
 
 /**
  * Gets a function that might be called by `call`.
@@ -63,3 +65,17 @@ predicate mayBenefitFromCallContext(Call call, Function f) { none() }
  * restricted to those `call`s for which a context might make a difference.
  */
 Function viableImplInCallContext(Call call, Call ctx) { none() }
+
+/** A parameter position represented by an integer. */
+class ParameterPosition extends int {
+  ParameterPosition() { any(ParameterNode p).isParameterOf(_, this) }
+}
+
+/** An argument position represented by an integer. */
+class ArgumentPosition extends int {
+  ArgumentPosition() { any(ArgumentNode a).argumentOf(_, this) }
+}
+
+/** Holds if arguments at position `apos` match parameters at position `ppos`. */
+pragma[inline]
+predicate parameterMatch(ParameterPosition ppos, ArgumentPosition apos) { ppos = apos }

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -62,6 +62,18 @@ predicate accessPathCostLimits(int apLimit, int tupleLimit) {
   tupleLimit = 1000
 }
 
+/**
+ * Holds if `arg` is an argument of `call` with an argument position that matches
+ * parameter position `ppos`.
+ */
+pragma[noinline]
+predicate argumentPositionMatch(DataFlowCall call, ArgNode arg, ParameterPosition ppos) {
+  exists(ArgumentPosition apos |
+    arg.argumentOf(call, apos) and
+    parameterMatch(ppos, apos)
+  )
+}
+
 /**
  * Provides a simple data-flow analysis for resolving lambda calls. The analysis
  * currently excludes read-steps, store-steps, and flow-through.
@@ -71,25 +83,27 @@ predicate accessPathCostLimits(int apLimit, int tupleLimit) {
  * calls. For this reason, we cannot reuse the code from `DataFlowImpl.qll` directly.
  */
 private module LambdaFlow {
-  private predicate viableParamNonLambda(DataFlowCall call, int i, ParamNode p) {
-    p.isParameterOf(viableCallable(call), i)
+  pragma[noinline]
+  private predicate viableParamNonLambda(DataFlowCall call, ParameterPosition ppos, ParamNode p) {
+    p.isParameterOf(viableCallable(call), ppos)
   }
 
-  private predicate viableParamLambda(DataFlowCall call, int i, ParamNode p) {
-    p.isParameterOf(viableCallableLambda(call, _), i)
+  pragma[noinline]
+  private predicate viableParamLambda(DataFlowCall call, ParameterPosition ppos, ParamNode p) {
+    p.isParameterOf(viableCallableLambda(call, _), ppos)
   }
 
   private predicate viableParamArgNonLambda(DataFlowCall call, ParamNode p, ArgNode arg) {
-    exists(int i |
-      viableParamNonLambda(call, i, p) and
-      arg.argumentOf(call, i)
+    exists(ParameterPosition ppos |
+      viableParamNonLambda(call, ppos, p) and
+      argumentPositionMatch(call, arg, ppos)
     )
   }
 
   private predicate viableParamArgLambda(DataFlowCall call, ParamNode p, ArgNode arg) {
-    exists(int i |
-      viableParamLambda(call, i, p) and
-      arg.argumentOf(call, i)
+    exists(ParameterPosition ppos |
+      viableParamLambda(call, ppos, p) and
+      argumentPositionMatch(call, arg, ppos)
     )
   }
 
@@ -322,7 +336,7 @@ private module Cached {
     or
     exists(ArgNode arg |
       result.(PostUpdateNode).getPreUpdateNode() = arg and
-      arg.argumentOf(call, k.(ParamUpdateReturnKind).getPosition())
+      arg.argumentOf(call, k.(ParamUpdateReturnKind).getAMatchingArgumentPosition())
     )
   }
 
@@ -330,7 +344,7 @@ private module Cached {
   predicate returnNodeExt(Node n, ReturnKindExt k) {
     k = TValueReturn(n.(ReturnNode).getKind())
     or
-    exists(ParamNode p, int pos |
+    exists(ParamNode p, ParameterPosition pos |
       parameterValueFlowsToPreUpdate(p, n) and
       p.isParameterOf(_, pos) and
       k = TParamUpdate(pos)
@@ -352,11 +366,13 @@ private module Cached {
   }
 
   cached
-  predicate parameterNode(Node p, DataFlowCallable c, int pos) { isParameterNode(p, c, pos) }
+  predicate parameterNode(Node p, DataFlowCallable c, ParameterPosition pos) {
+    isParameterNode(p, c, pos)
+  }
 
   cached
-  predicate argumentNode(Node n, DataFlowCall call, int pos) {
-    n.(ArgumentNode).argumentOf(call, pos)
+  predicate argumentNode(Node n, DataFlowCall call, ArgumentPosition pos) {
+    isArgumentNode(n, call, pos)
   }
 
   /**
@@ -374,12 +390,12 @@ private module Cached {
   }
 
   /**
-   * Holds if `p` is the `i`th parameter of a viable dispatch target of `call`.
-   * The instance parameter is considered to have index `-1`.
+   * Holds if `p` is the parameter of a viable dispatch target of `call`,
+   * and `p` has position `ppos`.
    */
   pragma[nomagic]
-  private predicate viableParam(DataFlowCall call, int i, ParamNode p) {
-    p.isParameterOf(viableCallableExt(call), i)
+  private predicate viableParam(DataFlowCall call, ParameterPosition ppos, ParamNode p) {
+    p.isParameterOf(viableCallableExt(call), ppos)
   }
 
   /**
@@ -388,9 +404,9 @@ private module Cached {
    */
   cached
   predicate viableParamArg(DataFlowCall call, ParamNode p, ArgNode arg) {
-    exists(int i |
-      viableParam(call, i, p) and
-      arg.argumentOf(call, i) and
+    exists(ParameterPosition ppos |
+      viableParam(call, ppos, p) and
+      argumentPositionMatch(call, arg, ppos) and
       compatibleTypes(getNodeDataFlowType(arg), getNodeDataFlowType(p))
     )
   }
@@ -862,7 +878,7 @@ private module Cached {
   cached
   newtype TReturnKindExt =
     TValueReturn(ReturnKind kind) or
-    TParamUpdate(int pos) { exists(ParamNode p | p.isParameterOf(_, pos)) }
+    TParamUpdate(ParameterPosition pos) { exists(ParamNode p | p.isParameterOf(_, pos)) }
 
   cached
   newtype TBooleanOption =
@@ -1054,9 +1070,9 @@ class ParamNode extends Node {
 
   /**
    * Holds if this node is the parameter of callable `c` at the specified
-   * (zero-based) position.
+   * position.
    */
-  predicate isParameterOf(DataFlowCallable c, int i) { parameterNode(this, c, i) }
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) { parameterNode(this, c, pos) }
 }
 
 /** A data-flow node that represents a call argument. */
@@ -1064,7 +1080,9 @@ class ArgNode extends Node {
   ArgNode() { argumentNode(this, _, _) }
 
   /** Holds if this argument occurs at the given position in the given call. */
-  final predicate argumentOf(DataFlowCall call, int pos) { argumentNode(this, call, pos) }
+  final predicate argumentOf(DataFlowCall call, ArgumentPosition pos) {
+    argumentNode(this, call, pos)
+  }
 }
 
 /**
@@ -1110,11 +1128,14 @@ class ValueReturnKind extends ReturnKindExt, TValueReturn {
 }
 
 class ParamUpdateReturnKind extends ReturnKindExt, TParamUpdate {
-  private int pos;
+  private ParameterPosition pos;
 
   ParamUpdateReturnKind() { this = TParamUpdate(pos) }
 
-  int getPosition() { result = pos }
+  ParameterPosition getPosition() { result = pos }
+
+  pragma[nomagic]
+  ArgumentPosition getAMatchingArgumentPosition() { parameterMatch(pos, result) }
 
   override string toString() { result = "param update " + pos }
 }

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

@@ -9,6 +9,31 @@ private import tainttracking1.TaintTrackingParameter::Private
 private import tainttracking1.TaintTrackingParameter::Public
 
 module Consistency {
+  private newtype TConsistencyConfiguration = MkConsistencyConfiguration()
+
+  /** A class for configuring the consistency queries. */
+  class ConsistencyConfiguration extends TConsistencyConfiguration {
+    string toString() { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `uniqueEnclosingCallable`. */
+    predicate uniqueEnclosingCallableExclude(Node n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `uniqueNodeLocation`. */
+    predicate uniqueNodeLocationExclude(Node n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `missingLocation`. */
+    predicate missingLocationExclude(Node n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `postWithInFlow`. */
+    predicate postWithInFlowExclude(Node n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `argHasPostUpdate`. */
+    predicate argHasPostUpdateExclude(ArgumentNode n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `reverseRead`. */
+    predicate reverseReadExclude(Node n) { none() }
+  }
+
   private class RelevantNode extends Node {
     RelevantNode() {
       this instanceof ArgumentNode or
@@ -33,6 +58,7 @@ module Consistency {
       n instanceof RelevantNode and
       c = count(nodeGetEnclosingCallable(n)) and
       c != 1 and
+      not any(ConsistencyConfiguration conf).uniqueEnclosingCallableExclude(n) and
       msg = "Node should have one enclosing callable but has " + c + "."
     )
   }
@@ -53,6 +79,7 @@ module Consistency {
           n.hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
         ) and
       c != 1 and
+      not any(ConsistencyConfiguration conf).uniqueNodeLocationExclude(n) and
       msg = "Node should have one location but has " + c + "."
     )
   }
@@ -63,7 +90,8 @@ module Consistency {
         strictcount(Node n |
           not exists(string filepath, int startline, int startcolumn, int endline, int endcolumn |
             n.hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
-          )
+          ) and
+          not any(ConsistencyConfiguration conf).missingLocationExclude(n)
         ) and
       msg = "Nodes without location: " + c
     )
@@ -159,12 +187,13 @@ module Consistency {
 
   query predicate reverseRead(Node n, string msg) {
     exists(Node n2 | readStep(n, _, n2) and hasPost(n2) and not hasPost(n)) and
+    not any(ConsistencyConfiguration conf).reverseReadExclude(n) and
     msg = "Origin of readStep is missing a PostUpdateNode."
   }
 
   query predicate argHasPostUpdate(ArgumentNode n, string msg) {
     not hasPost(n) and
-    not isImmutableOrUnobservable(n) and
+    not any(ConsistencyConfiguration c).argHasPostUpdateExclude(n) and
     msg = "ArgumentNode is missing PostUpdateNode."
   }
 
@@ -177,6 +206,7 @@ module Consistency {
     isPostUpdateNode(n) and
     not clearsContent(n, _) and
     simpleLocalFlowStep(_, n) and
+    not any(ConsistencyConfiguration c).postWithInFlowExclude(n) and
     msg = "PostUpdateNode should not be the target of local flow."
   }
 }

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -2,12 +2,20 @@ private import cpp
 private import DataFlowUtil
 private import DataFlowDispatch
 private import FlowVar
+private import DataFlowImplConsistency
 
 /** Gets the callable in which this node occurs. */
 DataFlowCallable nodeGetEnclosingCallable(Node n) { result = n.getEnclosingCallable() }
 
 /** Holds if `p` is a `ParameterNode` of `c` with position `pos`. */
-predicate isParameterNode(ParameterNode p, DataFlowCallable c, int pos) { p.isParameterOf(c, pos) }
+predicate isParameterNode(ParameterNode p, DataFlowCallable c, ParameterPosition pos) {
+  p.isParameterOf(c, pos)
+}
+
+/** Holds if `arg` is an `ArgumentNode` of `c` with position `pos`. */
+predicate isArgumentNode(ArgumentNode arg, DataFlowCall c, ArgumentPosition pos) {
+  arg.argumentOf(c, pos)
+}
 
 /** Gets the instance argument of a non-static call. */
 private Node getInstanceArgument(Call call) {
@@ -259,27 +267,6 @@ class Unit extends TUnit {
   string toString() { result = "unit" }
 }
 
-/**
- * Holds if `n` does not require a `PostUpdateNode` as it either cannot be
- * modified or its modification cannot be observed, for example if it is a
- * freshly created object that is not saved in a variable.
- *
- * This predicate is only used for consistency checks.
- */
-predicate isImmutableOrUnobservable(Node n) {
-  // Is the null pointer (or something that's not really a pointer)
-  exists(n.asExpr().getValue())
-  or
-  // Isn't a pointer or is a pointer to const
-  forall(DerivedType dt | dt = n.asExpr().getActualType() |
-    dt.getBaseType().isConst()
-    or
-    dt.getBaseType() instanceof RoutineType
-  )
-  // The above list of cases isn't exhaustive, but it narrows down the
-  // consistency alerts enough that most of them are interesting.
-}
-
 /** Holds if `n` should be hidden from path explanations. */
 predicate nodeIsHidden(Node n) { none() }
 
@@ -302,3 +289,19 @@ predicate additionalLambdaFlowStep(Node nodeFrom, Node nodeTo, boolean preserves
  * by default as a heuristic.
  */
 predicate allowParameterReturnInSelf(ParameterNode p) { none() }
+
+private class MyConsistencyConfiguration extends Consistency::ConsistencyConfiguration {
+  override predicate argHasPostUpdateExclude(ArgumentNode n) {
+    // Is the null pointer (or something that's not really a pointer)
+    exists(n.asExpr().getValue())
+    or
+    // Isn't a pointer or is a pointer to const
+    forall(DerivedType dt | dt = n.asExpr().getActualType() |
+      dt.getBaseType().isConst()
+      or
+      dt.getBaseType() instanceof RoutineType
+    )
+    // The above list of cases isn't exhaustive, but it narrows down the
+    // consistency alerts enough that most of them are interesting.
+  }
+}

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

@@ -118,7 +118,7 @@ class LambdaCapture extends Locatable, @lambdacapture {
    * An identifier is captured by reference if:
    *   - It is explicitly captured by reference.
    *   - It is implicitly captured, and the lambda's default capture mode is by-reference.
-   *   - The identifier is "this". [Said behaviour is dictated by the C++11 standard, but it
+   *   - The identifier is "this". [Said behavior is dictated by the C++11 standard, but it
    *                                is actually "*this" being captured rather than "this".]
    */
   predicate isCapturedByReference() { lambda_capture(this, _, _, _, true, _, _) }

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

@@ -2,6 +2,7 @@ private import cpp
 private import semmle.code.cpp.ir.IR
 private import semmle.code.cpp.ir.dataflow.DataFlow
 private import semmle.code.cpp.ir.dataflow.internal.DataFlowPrivate
+private import semmle.code.cpp.ir.dataflow.internal.DataFlowUtil
 private import DataFlowImplCommon as DataFlowImplCommon
 
 /**
@@ -62,7 +63,7 @@ private module VirtualDispatch {
         this.flowsFrom(other, allowOtherFromArg)
       |
         // Call argument
-        exists(DataFlowCall call, int i |
+        exists(DataFlowCall call, Position i |
           other
               .(DataFlow::ParameterNode)
               .isParameterOf(pragma[only_bind_into](call).getStaticCallTarget(), i) and
@@ -266,3 +267,7 @@ Function viableImplInCallContext(CallInstruction call, CallInstruction ctx) {
     result = ctx.getArgument(i).getUnconvertedResultExpression().(FunctionAccess).getTarget()
   )
 }
+
+/** Holds if arguments at position `apos` match parameters at position `ppos`. */
+pragma[inline]
+predicate parameterMatch(ParameterPosition ppos, ArgumentPosition apos) { ppos = apos }

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -256,11 +256,11 @@ private class ArgNodeEx extends NodeEx {
 private class ParamNodeEx extends NodeEx {
   ParamNodeEx() { this.asNode() instanceof ParamNode }
 
-  predicate isParameterOf(DataFlowCallable c, int i) {
-    this.asNode().(ParamNode).isParameterOf(c, i)
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
+    this.asNode().(ParamNode).isParameterOf(c, pos)
   }
 
-  int getPosition() { this.isParameterOf(_, result) }
+  ParameterPosition getPosition() { this.isParameterOf(_, result) }
 
   predicate allowParameterReturnInSelf() { allowParameterReturnInSelfCached(this.asNode()) }
 }
@@ -289,6 +289,7 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
     config.isBarrier(n)
@@ -307,11 +308,23 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
 }
 
 pragma[nomagic]
-private predicate sourceNode(NodeEx node, Configuration config) { config.isSource(node.asNode()) }
+private predicate sourceNode(NodeEx node, Configuration config) {
+  config.isSource(node.asNode()) and
+  not fullBarrier(node, config)
+}
 
 pragma[nomagic]
 private predicate sinkNode(NodeEx node, Configuration config) { config.isSink(node.asNode()) }
 
+/** Provides the relevant barriers for a step from `node1` to `node2`. */
+pragma[inline]
+private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
+  not fullBarrier(node1, config) and
+  not fullBarrier(node2, config)
+}
+
 /**
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
@@ -320,16 +333,14 @@ private predicate localFlowStep(NodeEx node1, NodeEx node2, Configuration config
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     simpleLocalFlowStepExt(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.asNode() = n and
-    node2.isImplicitReadNode(n, false)
+    node2.isImplicitReadNode(n, false) and
+    not fullBarrier(node1, config)
   )
 }
 
@@ -342,16 +353,14 @@ private predicate additionalLocalFlowStep(NodeEx node1, NodeEx node2, Configurat
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config)
+    stepFilter(node1, node2, config)
   )
   or
   exists(Node n |
     config.allowImplicitRead(n, _) and
     node1.isImplicitReadNode(n, true) and
-    node2.asNode() = n
+    node2.asNode() = n and
+    not fullBarrier(node2, config)
   )
 }
 
@@ -363,10 +372,7 @@ private predicate jumpStep(NodeEx node1, NodeEx node2, Configuration config) {
     node1.asNode() = n1 and
     node2.asNode() = n2 and
     jumpStepCached(n1, n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
@@ -380,16 +386,14 @@ private predicate additionalJumpStep(NodeEx node1, NodeEx node2, Configuration c
     node2.asNode() = n2 and
     config.isAdditionalFlowStep(n1, n2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
-    not outBarrier(node1, config) and
-    not inBarrier(node2, config) and
-    not fullBarrier(node1, config) and
-    not fullBarrier(node2, config) and
+    stepFilter(node1, node2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
 private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode())
+  read(node1.asNode(), c, node2.asNode()) and
+  stepFilter(node1, node2, config)
   or
   exists(Node n |
     node2.isImplicitReadNode(n, true) and
@@ -402,7 +406,8 @@ private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
   store(node1.asNode(), tc, node2.asNode(), contentType) and
-  read(_, tc.getContent(), _, config)
+  read(_, tc.getContent(), _, config) and
+  stepFilter(node1, node2, config)
 }
 
 pragma[nomagic]
@@ -451,63 +456,59 @@ private module Stage1 {
    * argument in a call.
    */
   predicate fwdFlow(NodeEx node, Cc cc, Configuration config) {
-    not fullBarrier(node, config) and
-    (
-      sourceNode(node, config) and
-      if hasSourceCallCtx(config) then cc = true else cc = false
+    sourceNode(node, config) and
+    if hasSourceCallCtx(config) then cc = true else cc = false
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      localFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, cc, config) and
+      additionalLocalFlowStep(mid, node, config)
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      jumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    exists(NodeEx mid |
+      fwdFlow(mid, _, config) and
+      additionalJumpStep(mid, node, config) and
+      cc = false
+    )
+    or
+    // store
+    exists(NodeEx mid |
+      useFieldFlow(config) and
+      fwdFlow(mid, cc, config) and
+      store(mid, _, node, _, config)
+    )
+    or
+    // read
+    exists(Content c |
+      fwdFlowRead(c, node, cc, config) and
+      fwdFlowConsCand(c, config)
+    )
+    or
+    // flow into a callable
+    exists(NodeEx arg |
+      fwdFlow(arg, _, config) and
+      viableParamArgEx(_, node, arg) and
+      cc = true and
+      not fullBarrier(node, config)
+    )
+    or
+    // flow out of a callable
+    exists(DataFlowCall call |
+      fwdFlowOut(call, node, false, config) and
+      cc = false
       or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        localFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, cc, config) and
-        additionalLocalFlowStep(mid, node, config)
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        jumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      exists(NodeEx mid |
-        fwdFlow(mid, _, config) and
-        additionalJumpStep(mid, node, config) and
-        cc = false
-      )
-      or
-      // store
-      exists(NodeEx mid |
-        useFieldFlow(config) and
-        fwdFlow(mid, cc, config) and
-        store(mid, _, node, _, config) and
-        not outBarrier(mid, config)
-      )
-      or
-      // read
-      exists(Content c |
-        fwdFlowRead(c, node, cc, config) and
-        fwdFlowConsCand(c, config) and
-        not inBarrier(node, config)
-      )
-      or
-      // flow into a callable
-      exists(NodeEx arg |
-        fwdFlow(arg, _, config) and
-        viableParamArgEx(_, node, arg) and
-        cc = true
-      )
-      or
-      // flow out of a callable
-      exists(DataFlowCall call |
-        fwdFlowOut(call, node, false, config) and
-        cc = false
-        or
-        fwdFlowOutFromArg(call, node, config) and
-        fwdFlowIsEntered(call, cc, config)
-      )
+      fwdFlowOutFromArg(call, node, config) and
+      fwdFlowIsEntered(call, cc, config)
     )
   }
 
@@ -547,7 +548,8 @@ private module Stage1 {
   private predicate fwdFlowOut(DataFlowCall call, NodeEx out, Cc cc, Configuration config) {
     exists(ReturnPosition pos |
       fwdFlowReturnPosition(pos, cc, config) and
-      viableReturnPosOutEx(call, pos, out)
+      viableReturnPosOutEx(call, pos, out) and
+      not fullBarrier(out, config)
     )
   }
 
@@ -773,6 +775,7 @@ private module Stage1 {
    * Holds if flow may enter through `p` and reach a return node making `p` a
    * candidate for the origin of a summary.
    */
+  pragma[nomagic]
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
     exists(ReturnKindExt kind |
       throughFlowNodeCand(p, config) and
@@ -1009,6 +1012,9 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  bindingset[node, ap]
+  private predicate filter(NodeEx node, Ap ap) { any() }
+
   bindingset[ap, contentType]
   private predicate typecheckStore(Ap ap, DataFlowType contentType) { any() }
 
@@ -1017,14 +1023,23 @@ private module Stage2 {
     PrevStage::revFlow(node, _, _, apa, config)
   }
 
+  bindingset[result, apa]
+  private ApApprox unbindApa(ApApprox apa) {
+    exists(ApApprox apa0 |
+      apa = pragma[only_bind_into](apa0) and result = pragma[only_bind_into](apa0)
+    )
+  }
+
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1037,6 +1052,13 @@ private module Stage2 {
    */
   pragma[nomagic]
   predicate fwdFlow(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
+    fwdFlow0(node, cc, argAp, ap, config) and
+    flowCand(node, unbindApa(getApprox(ap)), config) and
+    filter(node, ap)
+  }
+
+  pragma[nomagic]
+  private predicate fwdFlow0(NodeEx node, Cc cc, ApOption argAp, Ap ap, Configuration config) {
     flowCand(node, _, config) and
     sourceNode(node, config) and
     (if hasSourceCallCtx(config) then cc = ccSomeCall() else cc = ccNone()) and
@@ -1107,7 +1129,7 @@ private module Stage2 {
   ) {
     exists(DataFlowType contentType |
       fwdFlow(node1, cc, argAp, ap1, config) and
-      PrevStage::storeStepCand(node1, getApprox(ap1), tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, unbindApa(getApprox(ap1)), tc, node2, contentType, config) and
       typecheckStore(ap1, contentType)
     )
   }
@@ -1142,9 +1164,8 @@ private module Stage2 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1159,9 +1180,8 @@ private module Stage2 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1171,10 +1191,8 @@ private module Stage2 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1188,7 +1206,7 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p |
       fwdFlowIn(call, p, cc, _, argAp, ap, config) and
-      PrevStage::parameterMayFlowThrough(p, _, getApprox(ap), config)
+      PrevStage::parameterMayFlowThrough(p, _, unbindApa(getApprox(ap)), config)
     )
   }
 
@@ -1230,6 +1248,11 @@ private module Stage2 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -1306,7 +1329,7 @@ private module Stage2 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -1341,9 +1364,8 @@ private module Stage2 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1353,9 +1375,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1365,9 +1386,8 @@ private module Stage2 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1427,7 +1447,7 @@ private module Stage2 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -1707,12 +1727,14 @@ private module Stage3 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -1837,9 +1859,8 @@ private module Stage3 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1854,9 +1875,8 @@ private module Stage3 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1866,10 +1886,8 @@ private module Stage3 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -1925,6 +1943,11 @@ private module Stage3 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2001,7 +2024,7 @@ private module Stage3 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2036,9 +2059,8 @@ private module Stage3 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2048,9 +2070,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2060,9 +2081,8 @@ private module Stage3 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2122,7 +2142,7 @@ private module Stage3 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2473,12 +2493,14 @@ private module Stage4 {
 
   pragma[nomagic]
   private predicate flowThroughOutOfCall(
-    DataFlowCall call, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow, Configuration config
+    DataFlowCall call, CcCall ccc, RetNodeEx ret, NodeEx out, boolean allowsFieldFlow,
+    Configuration config
   ) {
     flowOutOfCall(call, ret, out, allowsFieldFlow, pragma[only_bind_into](config)) and
     PrevStage::callMayFlowThroughRev(call, pragma[only_bind_into](config)) and
     PrevStage::parameterMayFlowThrough(_, ret.getEnclosingCallable(), _,
-      pragma[only_bind_into](config))
+      pragma[only_bind_into](config)) and
+    ccc.matchesCall(call)
   }
 
   /**
@@ -2603,9 +2625,8 @@ private module Stage4 {
     exists(ArgNodeEx arg, boolean allowsFieldFlow |
       fwdFlow(arg, outercc, argAp, ap, config) and
       flowIntoCall(call, arg, p, allowsFieldFlow, config) and
-      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      innercc = getCallContextCall(call, p.getEnclosingCallable(), outercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2620,9 +2641,8 @@ private module Stage4 {
       fwdFlow(ret, innercc, argAp, ap, config) and
       flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
       inner = ret.getEnclosingCallable() and
-      ccOut = getCallContextReturn(inner, call, innercc)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      ccOut = getCallContextReturn(inner, call, innercc) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2632,10 +2652,8 @@ private module Stage4 {
   ) {
     exists(RetNodeEx ret, boolean allowsFieldFlow, CcCall ccc |
       fwdFlow(ret, ccc, apSome(argAp), ap, config) and
-      flowThroughOutOfCall(call, ret, out, allowsFieldFlow, config) and
-      ccc.matchesCall(call)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughOutOfCall(call, ccc, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2691,6 +2709,11 @@ private module Stage4 {
     callMayFlowThroughFwd(call, pragma[only_bind_into](config))
   }
 
+  pragma[nomagic]
+  private predicate returnNodeMayFlowThrough(RetNodeEx ret, Ap ap, Configuration config) {
+    fwdFlow(ret, any(CcCall ccc), apSome(_), ap, config)
+  }
+
   /**
    * Holds if `node` with access path `ap` is part of a path from a source to a
    * sink in the configuration `config`.
@@ -2767,7 +2790,7 @@ private module Stage4 {
     // flow out of a callable
     revFlowOut(_, node, _, _, ap, config) and
     toReturn = true and
-    if fwdFlow(node, any(CcCall ccc), apSome(_), ap, config)
+    if returnNodeMayFlowThrough(node, ap, config)
     then returnAp = apSome(ap)
     else returnAp = apNone()
   }
@@ -2802,9 +2825,8 @@ private module Stage4 {
   ) {
     exists(NodeEx out, boolean allowsFieldFlow |
       revFlow(out, toReturn, returnAp, ap, config) and
-      flowOutOfCall(call, ret, out, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowOutOfCall(call, ret, out, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2814,9 +2836,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, false, returnAp, ap, config) and
-      flowIntoCall(_, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowIntoCall(_, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2826,9 +2847,8 @@ private module Stage4 {
   ) {
     exists(ParamNodeEx p, boolean allowsFieldFlow |
       revFlow(p, true, apSome(returnAp), ap, config) and
-      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config)
-    |
-      ap instanceof ApNil or allowsFieldFlow = true
+      flowThroughIntoCall(call, arg, p, allowsFieldFlow, config) and
+      if allowsFieldFlow = false then ap instanceof ApNil else any()
     )
   }
 
@@ -2888,7 +2908,7 @@ private module Stage4 {
   }
 
   predicate parameterMayFlowThrough(ParamNodeEx p, DataFlowCallable c, Ap ap, Configuration config) {
-    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, int pos |
+    exists(RetNodeEx ret, Ap ap0, ReturnKindExt kind, ParameterPosition pos |
       parameterFlow(p, ap, ap0, c, config) and
       c = ret.getEnclosingCallable() and
       revFlow(pragma[only_bind_into](ret), true, apSome(_), pragma[only_bind_into](ap0),
@@ -2972,7 +2992,7 @@ private class SummaryCtxSome extends SummaryCtx, TSummaryCtxSome {
 
   SummaryCtxSome() { this = TSummaryCtxSome(p, ap) }
 
-  int getParameterPos() { p.isParameterOf(_, result) }
+  ParameterPosition getParameterPos() { p.isParameterOf(_, result) }
 
   ParamNodeEx getParamNode() { result = p }
 
@@ -3619,39 +3639,40 @@ private predicate pathOutOfCallable(PathNodeMid mid, NodeEx out, CallContext cc)
  */
 pragma[noinline]
 private predicate pathIntoArg(
-  PathNodeMid mid, int i, CallContext cc, DataFlowCall call, AccessPath ap, AccessPathApprox apa,
-  Configuration config
+  PathNodeMid mid, ParameterPosition ppos, CallContext cc, DataFlowCall call, AccessPath ap,
+  AccessPathApprox apa, Configuration config
 ) {
-  exists(ArgNode arg |
+  exists(ArgNode arg, ArgumentPosition apos |
     arg = mid.getNodeEx().asNode() and
     cc = mid.getCallContext() and
-    arg.argumentOf(call, i) and
+    arg.argumentOf(call, apos) and
     ap = mid.getAp() and
     apa = ap.getApprox() and
-    config = mid.getConfiguration()
+    config = mid.getConfiguration() and
+    parameterMatch(ppos, apos)
   )
 }
 
 pragma[nomagic]
 private predicate parameterCand(
-  DataFlowCallable callable, int i, AccessPathApprox apa, Configuration config
+  DataFlowCallable callable, ParameterPosition pos, AccessPathApprox apa, Configuration config
 ) {
   exists(ParamNodeEx p |
     Stage4::revFlow(p, _, _, apa, config) and
-    p.isParameterOf(callable, i)
+    p.isParameterOf(callable, pos)
   )
 }
 
 pragma[nomagic]
 private predicate pathIntoCallable0(
-  PathNodeMid mid, DataFlowCallable callable, int i, CallContext outercc, DataFlowCall call,
-  AccessPath ap, Configuration config
+  PathNodeMid mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
+  DataFlowCall call, AccessPath ap, Configuration config
 ) {
   exists(AccessPathApprox apa |
-    pathIntoArg(mid, pragma[only_bind_into](i), outercc, call, ap, pragma[only_bind_into](apa),
+    pathIntoArg(mid, pragma[only_bind_into](pos), outercc, call, ap, pragma[only_bind_into](apa),
       pragma[only_bind_into](config)) and
     callable = resolveCall(call, outercc) and
-    parameterCand(callable, pragma[only_bind_into](i), pragma[only_bind_into](apa),
+    parameterCand(callable, pragma[only_bind_into](pos), pragma[only_bind_into](apa),
       pragma[only_bind_into](config))
   )
 }
@@ -3666,9 +3687,9 @@ private predicate pathIntoCallable(
   PathNodeMid mid, ParamNodeEx p, CallContext outercc, CallContextCall innercc, SummaryCtx sc,
   DataFlowCall call, Configuration config
 ) {
-  exists(int i, DataFlowCallable callable, AccessPath ap |
-    pathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-    p.isParameterOf(callable, i) and
+  exists(ParameterPosition pos, DataFlowCallable callable, AccessPath ap |
+    pathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+    p.isParameterOf(callable, pos) and
     (
       sc = TSummaryCtxSome(p, ap)
       or
@@ -3692,7 +3713,7 @@ private predicate paramFlowsThrough(
   ReturnKindExt kind, CallContextCall cc, SummaryCtxSome sc, AccessPath ap, AccessPathApprox apa,
   Configuration config
 ) {
-  exists(PathNodeMid mid, RetNodeEx ret, int pos |
+  exists(PathNodeMid mid, RetNodeEx ret, ParameterPosition pos |
     mid.getNodeEx() = ret and
     kind = ret.getKind() and
     cc = mid.getCallContext() and
@@ -4421,24 +4442,25 @@ private module FlowExploration {
 
   pragma[noinline]
   private predicate partialPathIntoArg(
-    PartialPathNodeFwd mid, int i, CallContext cc, DataFlowCall call, PartialAccessPath ap,
-    Configuration config
+    PartialPathNodeFwd mid, ParameterPosition ppos, CallContext cc, DataFlowCall call,
+    PartialAccessPath ap, Configuration config
   ) {
-    exists(ArgNode arg |
+    exists(ArgNode arg, ArgumentPosition apos |
       arg = mid.getNodeEx().asNode() and
       cc = mid.getCallContext() and
-      arg.argumentOf(call, i) and
+      arg.argumentOf(call, apos) and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate partialPathIntoCallable0(
-    PartialPathNodeFwd mid, DataFlowCallable callable, int i, CallContext outercc,
+    PartialPathNodeFwd mid, DataFlowCallable callable, ParameterPosition pos, CallContext outercc,
     DataFlowCall call, PartialAccessPath ap, Configuration config
   ) {
-    partialPathIntoArg(mid, i, outercc, call, ap, config) and
+    partialPathIntoArg(mid, pos, outercc, call, ap, config) and
     callable = resolveCall(call, outercc)
   }
 
@@ -4447,9 +4469,9 @@ private module FlowExploration {
     TSummaryCtx1 sc1, TSummaryCtx2 sc2, DataFlowCall call, PartialAccessPath ap,
     Configuration config
   ) {
-    exists(int i, DataFlowCallable callable |
-      partialPathIntoCallable0(mid, callable, i, outercc, call, ap, config) and
-      p.isParameterOf(callable, i) and
+    exists(ParameterPosition pos, DataFlowCallable callable |
+      partialPathIntoCallable0(mid, callable, pos, outercc, call, ap, config) and
+      p.isParameterOf(callable, pos) and
       sc1 = TSummaryCtx1Param(p) and
       sc2 = TSummaryCtx2Some(ap)
     |
@@ -4613,22 +4635,23 @@ private module FlowExploration {
 
   pragma[nomagic]
   private predicate revPartialPathFlowsThrough(
-    int pos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2, RevPartialAccessPath ap,
-    Configuration config
+    ArgumentPosition apos, TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2,
+    RevPartialAccessPath ap, Configuration config
   ) {
-    exists(PartialPathNodeRev mid, ParamNodeEx p |
+    exists(PartialPathNodeRev mid, ParamNodeEx p, ParameterPosition ppos |
       mid.getNodeEx() = p and
-      p.getPosition() = pos and
+      p.getPosition() = ppos and
       sc1 = mid.getSummaryCtx1() and
       sc2 = mid.getSummaryCtx2() and
       ap = mid.getAp() and
-      config = mid.getConfiguration()
+      config = mid.getConfiguration() and
+      parameterMatch(ppos, apos)
     )
   }
 
   pragma[nomagic]
   private predicate revPartialPathThroughCallable0(
-    DataFlowCall call, PartialPathNodeRev mid, int pos, RevPartialAccessPath ap,
+    DataFlowCall call, PartialPathNodeRev mid, ArgumentPosition pos, RevPartialAccessPath ap,
     Configuration config
   ) {
     exists(TRevSummaryCtx1Some sc1, TRevSummaryCtx2Some sc2 |
@@ -4641,7 +4664,7 @@ private module FlowExploration {
   private predicate revPartialPathThroughCallable(
     PartialPathNodeRev mid, ArgNodeEx node, RevPartialAccessPath ap, Configuration config
   ) {
-    exists(DataFlowCall call, int pos |
+    exists(DataFlowCall call, ArgumentPosition pos |
       revPartialPathThroughCallable0(call, mid, pos, ap, config) and
       node.asNode().(ArgNode).argumentOf(call, pos)
     )

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

@@ -62,6 +62,18 @@ predicate accessPathCostLimits(int apLimit, int tupleLimit) {
   tupleLimit = 1000
 }
 
+/**
+ * Holds if `arg` is an argument of `call` with an argument position that matches
+ * parameter position `ppos`.
+ */
+pragma[noinline]
+predicate argumentPositionMatch(DataFlowCall call, ArgNode arg, ParameterPosition ppos) {
+  exists(ArgumentPosition apos |
+    arg.argumentOf(call, apos) and
+    parameterMatch(ppos, apos)
+  )
+}
+
 /**
  * Provides a simple data-flow analysis for resolving lambda calls. The analysis
  * currently excludes read-steps, store-steps, and flow-through.
@@ -71,25 +83,27 @@ predicate accessPathCostLimits(int apLimit, int tupleLimit) {
  * calls. For this reason, we cannot reuse the code from `DataFlowImpl.qll` directly.
  */
 private module LambdaFlow {
-  private predicate viableParamNonLambda(DataFlowCall call, int i, ParamNode p) {
-    p.isParameterOf(viableCallable(call), i)
+  pragma[noinline]
+  private predicate viableParamNonLambda(DataFlowCall call, ParameterPosition ppos, ParamNode p) {
+    p.isParameterOf(viableCallable(call), ppos)
   }
 
-  private predicate viableParamLambda(DataFlowCall call, int i, ParamNode p) {
-    p.isParameterOf(viableCallableLambda(call, _), i)
+  pragma[noinline]
+  private predicate viableParamLambda(DataFlowCall call, ParameterPosition ppos, ParamNode p) {
+    p.isParameterOf(viableCallableLambda(call, _), ppos)
   }
 
   private predicate viableParamArgNonLambda(DataFlowCall call, ParamNode p, ArgNode arg) {
-    exists(int i |
-      viableParamNonLambda(call, i, p) and
-      arg.argumentOf(call, i)
+    exists(ParameterPosition ppos |
+      viableParamNonLambda(call, ppos, p) and
+      argumentPositionMatch(call, arg, ppos)
     )
   }
 
   private predicate viableParamArgLambda(DataFlowCall call, ParamNode p, ArgNode arg) {
-    exists(int i |
-      viableParamLambda(call, i, p) and
-      arg.argumentOf(call, i)
+    exists(ParameterPosition ppos |
+      viableParamLambda(call, ppos, p) and
+      argumentPositionMatch(call, arg, ppos)
     )
   }
 
@@ -322,7 +336,7 @@ private module Cached {
     or
     exists(ArgNode arg |
       result.(PostUpdateNode).getPreUpdateNode() = arg and
-      arg.argumentOf(call, k.(ParamUpdateReturnKind).getPosition())
+      arg.argumentOf(call, k.(ParamUpdateReturnKind).getAMatchingArgumentPosition())
     )
   }
 
@@ -330,7 +344,7 @@ private module Cached {
   predicate returnNodeExt(Node n, ReturnKindExt k) {
     k = TValueReturn(n.(ReturnNode).getKind())
     or
-    exists(ParamNode p, int pos |
+    exists(ParamNode p, ParameterPosition pos |
       parameterValueFlowsToPreUpdate(p, n) and
       p.isParameterOf(_, pos) and
       k = TParamUpdate(pos)
@@ -352,11 +366,13 @@ private module Cached {
   }
 
   cached
-  predicate parameterNode(Node p, DataFlowCallable c, int pos) { isParameterNode(p, c, pos) }
+  predicate parameterNode(Node p, DataFlowCallable c, ParameterPosition pos) {
+    isParameterNode(p, c, pos)
+  }
 
   cached
-  predicate argumentNode(Node n, DataFlowCall call, int pos) {
-    n.(ArgumentNode).argumentOf(call, pos)
+  predicate argumentNode(Node n, DataFlowCall call, ArgumentPosition pos) {
+    isArgumentNode(n, call, pos)
   }
 
   /**
@@ -374,12 +390,12 @@ private module Cached {
   }
 
   /**
-   * Holds if `p` is the `i`th parameter of a viable dispatch target of `call`.
-   * The instance parameter is considered to have index `-1`.
+   * Holds if `p` is the parameter of a viable dispatch target of `call`,
+   * and `p` has position `ppos`.
    */
   pragma[nomagic]
-  private predicate viableParam(DataFlowCall call, int i, ParamNode p) {
-    p.isParameterOf(viableCallableExt(call), i)
+  private predicate viableParam(DataFlowCall call, ParameterPosition ppos, ParamNode p) {
+    p.isParameterOf(viableCallableExt(call), ppos)
   }
 
   /**
@@ -388,9 +404,9 @@ private module Cached {
    */
   cached
   predicate viableParamArg(DataFlowCall call, ParamNode p, ArgNode arg) {
-    exists(int i |
-      viableParam(call, i, p) and
-      arg.argumentOf(call, i) and
+    exists(ParameterPosition ppos |
+      viableParam(call, ppos, p) and
+      argumentPositionMatch(call, arg, ppos) and
       compatibleTypes(getNodeDataFlowType(arg), getNodeDataFlowType(p))
     )
   }
@@ -862,7 +878,7 @@ private module Cached {
   cached
   newtype TReturnKindExt =
     TValueReturn(ReturnKind kind) or
-    TParamUpdate(int pos) { exists(ParamNode p | p.isParameterOf(_, pos)) }
+    TParamUpdate(ParameterPosition pos) { exists(ParamNode p | p.isParameterOf(_, pos)) }
 
   cached
   newtype TBooleanOption =
@@ -1054,9 +1070,9 @@ class ParamNode extends Node {
 
   /**
    * Holds if this node is the parameter of callable `c` at the specified
-   * (zero-based) position.
+   * position.
    */
-  predicate isParameterOf(DataFlowCallable c, int i) { parameterNode(this, c, i) }
+  predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) { parameterNode(this, c, pos) }
 }
 
 /** A data-flow node that represents a call argument. */
@@ -1064,7 +1080,9 @@ class ArgNode extends Node {
   ArgNode() { argumentNode(this, _, _) }
 
   /** Holds if this argument occurs at the given position in the given call. */
-  final predicate argumentOf(DataFlowCall call, int pos) { argumentNode(this, call, pos) }
+  final predicate argumentOf(DataFlowCall call, ArgumentPosition pos) {
+    argumentNode(this, call, pos)
+  }
 }
 
 /**
@@ -1110,11 +1128,14 @@ class ValueReturnKind extends ReturnKindExt, TValueReturn {
 }
 
 class ParamUpdateReturnKind extends ReturnKindExt, TParamUpdate {
-  private int pos;
+  private ParameterPosition pos;
 
   ParamUpdateReturnKind() { this = TParamUpdate(pos) }
 
-  int getPosition() { result = pos }
+  ParameterPosition getPosition() { result = pos }
+
+  pragma[nomagic]
+  ArgumentPosition getAMatchingArgumentPosition() { parameterMatch(pos, result) }
 
   override string toString() { result = "param update " + pos }
 }

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

@@ -9,6 +9,31 @@ private import tainttracking1.TaintTrackingParameter::Private
 private import tainttracking1.TaintTrackingParameter::Public
 
 module Consistency {
+  private newtype TConsistencyConfiguration = MkConsistencyConfiguration()
+
+  /** A class for configuring the consistency queries. */
+  class ConsistencyConfiguration extends TConsistencyConfiguration {
+    string toString() { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `uniqueEnclosingCallable`. */
+    predicate uniqueEnclosingCallableExclude(Node n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `uniqueNodeLocation`. */
+    predicate uniqueNodeLocationExclude(Node n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `missingLocation`. */
+    predicate missingLocationExclude(Node n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `postWithInFlow`. */
+    predicate postWithInFlowExclude(Node n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `argHasPostUpdate`. */
+    predicate argHasPostUpdateExclude(ArgumentNode n) { none() }
+
+    /** Holds if `n` should be excluded from the consistency test `reverseRead`. */
+    predicate reverseReadExclude(Node n) { none() }
+  }
+
   private class RelevantNode extends Node {
     RelevantNode() {
       this instanceof ArgumentNode or
@@ -33,6 +58,7 @@ module Consistency {
       n instanceof RelevantNode and
       c = count(nodeGetEnclosingCallable(n)) and
       c != 1 and
+      not any(ConsistencyConfiguration conf).uniqueEnclosingCallableExclude(n) and
       msg = "Node should have one enclosing callable but has " + c + "."
     )
   }
@@ -53,6 +79,7 @@ module Consistency {
           n.hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
         ) and
       c != 1 and
+      not any(ConsistencyConfiguration conf).uniqueNodeLocationExclude(n) and
       msg = "Node should have one location but has " + c + "."
     )
   }
@@ -63,7 +90,8 @@ module Consistency {
         strictcount(Node n |
           not exists(string filepath, int startline, int startcolumn, int endline, int endcolumn |
             n.hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
-          )
+          ) and
+          not any(ConsistencyConfiguration conf).missingLocationExclude(n)
         ) and
       msg = "Nodes without location: " + c
     )
@@ -159,12 +187,13 @@ module Consistency {
 
   query predicate reverseRead(Node n, string msg) {
     exists(Node n2 | readStep(n, _, n2) and hasPost(n2) and not hasPost(n)) and
+    not any(ConsistencyConfiguration conf).reverseReadExclude(n) and
     msg = "Origin of readStep is missing a PostUpdateNode."
   }
 
   query predicate argHasPostUpdate(ArgumentNode n, string msg) {
     not hasPost(n) and
-    not isImmutableOrUnobservable(n) and
+    not any(ConsistencyConfiguration c).argHasPostUpdateExclude(n) and
     msg = "ArgumentNode is missing PostUpdateNode."
   }
 
@@ -177,6 +206,7 @@ module Consistency {
     isPostUpdateNode(n) and
     not clearsContent(n, _) and
     simpleLocalFlowStep(_, n) and
+    not any(ConsistencyConfiguration c).postWithInFlowExclude(n) and
     msg = "PostUpdateNode should not be the target of local flow."
   }
 }

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

@@ -2,12 +2,20 @@ private import cpp
 private import DataFlowUtil
 private import semmle.code.cpp.ir.IR
 private import DataFlowDispatch
+private import DataFlowImplConsistency
 
 /** Gets the callable in which this node occurs. */
 DataFlowCallable nodeGetEnclosingCallable(Node n) { result = n.getEnclosingCallable() }
 
 /** Holds if `p` is a `ParameterNode` of `c` with position `pos`. */
-predicate isParameterNode(ParameterNode p, DataFlowCallable c, int pos) { p.isParameterOf(c, pos) }
+predicate isParameterNode(ParameterNode p, DataFlowCallable c, ParameterPosition pos) {
+  p.isParameterOf(c, pos)
+}
+
+/** Holds if `arg` is an `ArgumentNode` of `c` with position `pos`. */
+predicate isArgumentNode(ArgumentNode arg, DataFlowCall c, ArgumentPosition pos) {
+  arg.argumentOf(c, pos)
+}
 
 /**
  * A data flow node that occurs as the argument of a call and is passed as-is
@@ -19,7 +27,7 @@ abstract class ArgumentNode extends OperandNode {
    * Holds if this argument occurs at the given position in the given call.
    * The instance argument is considered to have index `-1`.
    */
-  abstract predicate argumentOf(DataFlowCall call, int pos);
+  abstract predicate argumentOf(DataFlowCall call, ArgumentPosition pos);
 
   /** Gets the call in which this node is an argument. */
   DataFlowCall getCall() { this.argumentOf(result, _) }
@@ -34,7 +42,9 @@ private class PrimaryArgumentNode extends ArgumentNode {
 
   PrimaryArgumentNode() { exists(CallInstruction call | op = call.getAnArgumentOperand()) }
 
-  override predicate argumentOf(DataFlowCall call, int pos) { op = call.getArgumentOperand(pos) }
+  override predicate argumentOf(DataFlowCall call, ArgumentPosition pos) {
+    op = call.getArgumentOperand(pos.(DirectPosition).getIndex())
+  }
 
   override string toString() {
     exists(Expr unconverted |
@@ -63,9 +73,9 @@ private class SideEffectArgumentNode extends ArgumentNode {
 
   SideEffectArgumentNode() { op = read.getSideEffectOperand() }
 
-  override predicate argumentOf(DataFlowCall call, int pos) {
+  override predicate argumentOf(DataFlowCall call, ArgumentPosition pos) {
     read.getPrimaryInstruction() = call and
-    pos = getArgumentPosOfSideEffect(read.getIndex())
+    pos.(IndirectionPosition).getIndex() = read.getIndex()
   }
 
   override string toString() {
@@ -82,6 +92,54 @@ private class SideEffectArgumentNode extends ArgumentNode {
   }
 }
 
+/** A parameter position represented by an integer. */
+class ParameterPosition = Position;
+
+/** An argument position represented by an integer. */
+class ArgumentPosition = Position;
+
+class Position extends TPosition {
+  abstract string toString();
+}
+
+class DirectPosition extends TDirectPosition {
+  int index;
+
+  DirectPosition() { this = TDirectPosition(index) }
+
+  string toString() {
+    index = -1 and
+    result = "this"
+    or
+    index != -1 and
+    result = index.toString()
+  }
+
+  int getIndex() { result = index }
+}
+
+class IndirectionPosition extends TIndirectionPosition {
+  int index;
+
+  IndirectionPosition() { this = TIndirectionPosition(index) }
+
+  string toString() {
+    index = -1 and
+    result = "this"
+    or
+    index != -1 and
+    result = index.toString()
+  }
+
+  int getIndex() { result = index }
+}
+
+newtype TPosition =
+  TDirectPosition(int index) { exists(any(CallInstruction c).getArgument(index)) } or
+  TIndirectionPosition(int index) {
+    exists(ReadSideEffectInstruction instr | instr.getIndex() = index)
+  }
+
 private newtype TReturnKind =
   TNormalReturnKind() or
   TIndirectReturnKind(ParameterIndex index)
@@ -285,19 +343,6 @@ class Unit extends TUnit {
   string toString() { result = "unit" }
 }
 
-/**
- * Holds if `n` does not require a `PostUpdateNode` as it either cannot be
- * modified or its modification cannot be observed, for example if it is a
- * freshly created object that is not saved in a variable.
- *
- * This predicate is only used for consistency checks.
- */
-predicate isImmutableOrUnobservable(Node n) {
-  // The rules for whether an IR argument gets a post-update node are too
-  // complex to model here.
-  any()
-}
-
 /** Holds if `n` should be hidden from path explanations. */
 predicate nodeIsHidden(Node n) {
   n instanceof OperandNode and not n instanceof ArgumentNode
@@ -330,3 +375,11 @@ predicate additionalLambdaFlowStep(Node nodeFrom, Node nodeTo, boolean preserves
  * by default as a heuristic.
  */
 predicate allowParameterReturnInSelf(ParameterNode p) { none() }
+
+private class MyConsistencyConfiguration extends Consistency::ConsistencyConfiguration {
+  override predicate argHasPostUpdateExclude(ArgumentNode n) {
+    // The rules for whether an IR argument gets a post-update node are too
+    // complex to model here.
+    any()
+  }
+}

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

@@ -452,7 +452,7 @@ class SsaPhiNode extends Node, TSsaPhiNode {
 
   /** Holds if this phi node has input from the `rnk`'th write operation in block `block`. */
   final predicate hasInputAtRankInBlock(IRBlock block, int rnk) {
-    hasInputAtRankInBlock(block, rnk, _)
+    this.hasInputAtRankInBlock(block, rnk, _)
   }
 
   /**
@@ -490,19 +490,6 @@ class ExprNode extends InstructionNode {
   override string toString() { result = this.asConvertedExpr().toString() }
 }
 
-/**
- * INTERNAL: do not use. Translates a parameter/argument index into a negative
- * number that denotes the index of its side effect (pointer indirection).
- */
-bindingset[index]
-int getArgumentPosOfSideEffect(int index) {
-  // -1 -> -2
-  //  0 -> -3
-  //  1 -> -4
-  // ...
-  result = -3 - index
-}
-
 /**
  * The value of a parameter at function entry, viewed as a node in a data
  * flow graph. This includes both explicit parameters such as `x` in `f(x)`
@@ -525,7 +512,7 @@ class ParameterNode extends InstructionNode {
    * implicit `this` parameter is considered to have position `-1`, and
    * pointer-indirection parameters are at further negative positions.
    */
-  predicate isParameterOf(Function f, int pos) { none() } // overridden by subclasses
+  predicate isParameterOf(Function f, ParameterPosition pos) { none() } // overridden by subclasses
 }
 
 /** An explicit positional parameter, not including `this` or `...`. */
@@ -534,8 +521,8 @@ private class ExplicitParameterNode extends ParameterNode {
 
   ExplicitParameterNode() { exists(instr.getParameter()) }
 
-  override predicate isParameterOf(Function f, int pos) {
-    f.getParameter(pos) = instr.getParameter()
+  override predicate isParameterOf(Function f, ParameterPosition pos) {
+    f.getParameter(pos.(DirectPosition).getIndex()) = instr.getParameter()
   }
 
   /** Gets the `Parameter` associated with this node. */
@@ -550,8 +537,8 @@ class ThisParameterNode extends ParameterNode {
 
   ThisParameterNode() { instr.getIRVariable() instanceof IRThisVariable }
 
-  override predicate isParameterOf(Function f, int pos) {
-    pos = -1 and instr.getEnclosingFunction() = f
+  override predicate isParameterOf(Function f, ParameterPosition pos) {
+    pos.(DirectPosition).getIndex() = -1 and instr.getEnclosingFunction() = f
   }
 
   override string toString() { result = "this" }
@@ -561,12 +548,12 @@ class ThisParameterNode extends ParameterNode {
 class ParameterIndirectionNode extends ParameterNode {
   override InitializeIndirectionInstruction instr;
 
-  override predicate isParameterOf(Function f, int pos) {
+  override predicate isParameterOf(Function f, ParameterPosition pos) {
     exists(int index |
       instr.getEnclosingFunction() = f and
       instr.hasIndex(index)
     |
-      pos = getArgumentPosOfSideEffect(index)
+      pos.(IndirectionPosition).getIndex() = index
     )
   }
 

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

@@ -659,4 +659,15 @@ module Consistency {
     not phiHasInputFromBlock(_, def, _) and
     not uncertainWriteDefinitionInput(_, def)
   }
+
+  query predicate notDominatedByDef(RelevantDefinition def, SourceVariable v, BasicBlock bb, int i) {
+    exists(BasicBlock bbDef, int iDef | def.definesAt(v, bbDef, iDef) |
+      ssaDefReachesReadWithinBlock(v, def, bb, i) and
+      (bb != bbDef or i < iDef)
+      or
+      ssaDefReachesRead(v, def, bb, i) and
+      not ssaDefReachesReadWithinBlock(v, def, bb, i) and
+      not def.definesAt(v, getImmediateBasicBlockDominator*(bb), _)
+    )
+  }
 }

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

@@ -51,16 +51,6 @@ private newtype TDefOrUse =
   TExplicitUse(Operand op) { isExplicitUse(op) } or
   TReturnParamIndirection(Operand op) { returnParameterIndirection(op, _) }
 
-pragma[nomagic]
-private int getRank(DefOrUse defOrUse, IRBlock block) {
-  defOrUse =
-    rank[result](int i, DefOrUse cand |
-      block.getInstruction(i) = toInstruction(cand)
-    |
-      cand order by i
-    )
-}
-
 private class DefOrUse extends TDefOrUse {
   /** Gets the instruction associated with this definition, if any. */
   Instruction asDef() { none() }
@@ -74,9 +64,10 @@ private class DefOrUse extends TDefOrUse {
   /** Gets the block of this definition or use. */
   abstract IRBlock getBlock();
 
-  /** Holds if this definition or use has rank `rank` in block `block`. */
-  cached
-  final predicate hasRankInBlock(IRBlock block, int rnk) { rnk = getRank(this, block) }
+  /** Holds if this definition or use has index `index` in block `block`. */
+  final predicate hasIndexInBlock(IRBlock block, int index) {
+    block.getInstruction(index) = toInstruction(this)
+  }
 
   /** Gets the location of this element. */
   abstract Cpp::Location getLocation();
@@ -313,8 +304,8 @@ cached
 private module Cached {
   private predicate defUseFlow(Node nodeFrom, Node nodeTo) {
     exists(IRBlock bb1, int i1, IRBlock bb2, int i2, DefOrUse defOrUse, Use use |
-      defOrUse.hasRankInBlock(bb1, i1) and
-      use.hasRankInBlock(bb2, i2) and
+      defOrUse.hasIndexInBlock(bb1, i1) and
+      use.hasIndexInBlock(bb2, i2) and
       adjacentDefRead(_, bb1, i1, bb2, i2) and
       nodeFrom.asInstruction() = toInstruction(defOrUse) and
       flowOutOfAddressStep(use.getOperand(), nodeTo)
@@ -326,9 +317,9 @@ private module Cached {
     exists(IRBlock bb1, int i1, IRBlock bb2, int i2, Def def, Use use |
       nodeFrom.isTerminal() and
       def.getInstruction() = nodeFrom.getStoreInstruction() and
-      def.hasRankInBlock(bb1, i1) and
+      def.hasIndexInBlock(bb1, i1) and
       adjacentDefRead(_, bb1, i1, bb2, i2) and
-      use.hasRankInBlock(bb2, i2) and
+      use.hasIndexInBlock(bb2, i2) and
       flowOutOfAddressStep(use.getOperand(), nodeTo)
     )
     or
@@ -359,8 +350,8 @@ private module Cached {
 
   private predicate fromReadNode(ReadNode nodeFrom, Node nodeTo) {
     exists(IRBlock bb1, int i1, IRBlock bb2, int i2, Use use1, Use use2 |
-      use1.hasRankInBlock(bb1, i1) and
-      use2.hasRankInBlock(bb2, i2) and
+      use1.hasIndexInBlock(bb1, i1) and
+      use2.hasIndexInBlock(bb2, i2) and
       use1.getOperand().getDef() = nodeFrom.getInstruction() and
       adjacentDefRead(_, bb1, i1, bb2, i2) and
       flowOutOfAddressStep(use2.getOperand(), nodeTo)
@@ -371,7 +362,7 @@ private module Cached {
     exists(PhiNode phi, Use use, IRBlock block, int rnk |
       phi = nodeFrom.getPhiNode() and
       adjacentDefRead(phi, _, _, block, rnk) and
-      use.hasRankInBlock(block, rnk) and
+      use.hasIndexInBlock(block, rnk) and
       flowOutOfAddressStep(use.getOperand(), nodeTo)
     )
   }
@@ -379,7 +370,7 @@ private module Cached {
   private predicate toPhiNode(Node nodeFrom, SsaPhiNode nodeTo) {
     // Flow to phi nodes
     exists(Def def, IRBlock block, int rnk |
-      def.hasRankInBlock(block, rnk) and
+      def.hasIndexInBlock(block, rnk) and
       nodeTo.hasInputAtRankInBlock(block, rnk)
     |
       exists(StoreNodeInstr storeNode |
@@ -512,8 +503,8 @@ private module Cached {
     |
       store = def.getInstruction() and
       store.getSourceValueOperand() = operand and
-      def.hasRankInBlock(block1, rnk1) and
-      use.hasRankInBlock(block2, rnk2) and
+      def.hasIndexInBlock(block1, rnk1) and
+      use.hasIndexInBlock(block2, rnk2) and
       adjacentDefRead(_, block1, rnk1, block2, rnk2)
     |
       // The shared SSA library has determined that `use` is the next use of the operand
@@ -543,12 +534,12 @@ private module Cached {
     not operand = getSourceAddressOperand(_) and
     exists(Use use1, Use use2, IRBlock block1, int rnk1, IRBlock block2, int rnk2 |
       use1.getOperand() = operand and
-      use1.hasRankInBlock(block1, rnk1) and
+      use1.hasIndexInBlock(block1, rnk1) and
       // Don't flow to the next use if this use is part of a store operation that totally
       // overrides a variable.
       not explicitWrite(true, _, use1.getOperand().getDef()) and
       adjacentDefRead(_, block1, rnk1, block2, rnk2) and
-      use2.hasRankInBlock(block2, rnk2) and
+      use2.hasIndexInBlock(block2, rnk2) and
       flowOutOfAddressStep(use2.getOperand(), nodeTo)
     )
     or
@@ -620,7 +611,7 @@ import Cached
 predicate variableWrite(IRBlock bb, int i, SourceVariable v, boolean certain) {
   DataFlowImplCommon::forceCachingInSameStage() and
   exists(Def def |
-    def.hasRankInBlock(bb, i) and
+    def.hasIndexInBlock(bb, i) and
     v = def.getSourceVariable() and
     (if def.isCertain() then certain = true else certain = false)
   )
@@ -632,7 +623,7 @@ predicate variableWrite(IRBlock bb, int i, SourceVariable v, boolean certain) {
  */
 predicate variableRead(IRBlock bb, int i, SourceVariable v, boolean certain) {
   exists(Use use |
-    use.hasRankInBlock(bb, i) and
+    use.hasIndexInBlock(bb, i) and
     v = use.getSourceVariable() and
     certain = true
   )

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

@@ -307,7 +307,7 @@ class NonPhiMemoryOperand extends NonPhiOperand, MemoryOperand, TNonPhiMemoryOpe
   final override string toString() { result = tag.toString() }
 
   final override Instruction getAnyDef() {
-    result = unique(Instruction defInstr | hasDefinition(defInstr, _))
+    result = unique(Instruction defInstr | this.hasDefinition(defInstr, _))
   }
 
   final override Overlap getDefinitionOverlap() { this.hasDefinition(_, result) }

cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/internal/AliasAnalysis.qll

@@ -266,6 +266,20 @@ private predicate operandReturned(Operand operand, IntValue bitOffset) {
   bitOffset = Ints::unknown()
 }
 
+pragma[nomagic]
+private predicate initializeParameterInstructionHasVariable(
+  IRVariable var, InitializeParameterInstruction init
+) {
+  init.getIRVariable() = var
+}
+
+private predicate instructionInitializesThisInFunction(
+  Language::Function f, InitializeParameterInstruction init
+) {
+  initializeParameterInstructionHasVariable(any(IRThisVariable var), pragma[only_bind_into](init)) and
+  init.getEnclosingFunction() = f
+}
+
 private predicate isArgumentForParameter(
   CallInstruction ci, Operand operand, InitializeParameterInstruction init
 ) {
@@ -275,8 +289,7 @@ private predicate isArgumentForParameter(
     (
       init.getParameter() = f.getParameter(operand.(PositionalArgumentOperand).getIndex())
       or
-      init.getIRVariable() instanceof IRThisVariable and
-      unique( | | init.getEnclosingFunction()) = f and
+      instructionInitializesThisInFunction(f, init) and
       operand instanceof ThisArgumentOperand
     ) and
     not Language::isFunctionVirtual(f) and

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/Operand.qll

@@ -307,7 +307,7 @@ class NonPhiMemoryOperand extends NonPhiOperand, MemoryOperand, TNonPhiMemoryOpe
   final override string toString() { result = tag.toString() }
 
   final override Instruction getAnyDef() {
-    result = unique(Instruction defInstr | hasDefinition(defInstr, _))
+    result = unique(Instruction defInstr | this.hasDefinition(defInstr, _))
   }
 
   final override Overlap getDefinitionOverlap() { this.hasDefinition(_, result) }

cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/Operand.qll

@@ -307,7 +307,7 @@ class NonPhiMemoryOperand extends NonPhiOperand, MemoryOperand, TNonPhiMemoryOpe
   final override string toString() { result = tag.toString() }
 
   final override Instruction getAnyDef() {
-    result = unique(Instruction defInstr | hasDefinition(defInstr, _))
+    result = unique(Instruction defInstr | this.hasDefinition(defInstr, _))
   }
 
   final override Overlap getDefinitionOverlap() { this.hasDefinition(_, result) }

cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/internal/AliasAnalysis.qll

@@ -266,6 +266,20 @@ private predicate operandReturned(Operand operand, IntValue bitOffset) {
   bitOffset = Ints::unknown()
 }
 
+pragma[nomagic]
+private predicate initializeParameterInstructionHasVariable(
+  IRVariable var, InitializeParameterInstruction init
+) {
+  init.getIRVariable() = var
+}
+
+private predicate instructionInitializesThisInFunction(
+  Language::Function f, InitializeParameterInstruction init
+) {
+  initializeParameterInstructionHasVariable(any(IRThisVariable var), pragma[only_bind_into](init)) and
+  init.getEnclosingFunction() = f
+}
+
 private predicate isArgumentForParameter(
   CallInstruction ci, Operand operand, InitializeParameterInstruction init
 ) {
@@ -275,8 +289,7 @@ private predicate isArgumentForParameter(
     (
       init.getParameter() = f.getParameter(operand.(PositionalArgumentOperand).getIndex())
       or
-      init.getIRVariable() instanceof IRThisVariable and
-      unique( | | init.getEnclosingFunction()) = f and
+      instructionInitializesThisInFunction(f, init) and
       operand instanceof ThisArgumentOperand
     ) and
     not Language::isFunctionVirtual(f) and

cpp/ql/lib/semmle/code/cpp/security/BufferWrite.qll

@@ -71,13 +71,30 @@ abstract class BufferWrite extends Expr {
    */
   int getMaxData() { none() }
 
+  /**
+   * Gets an upper bound to the amount of data that's being written (if one
+   * can be found), specifying the reason for the estimation.
+   */
+  int getMaxData(BufferWriteEstimationReason reason) {
+    reason instanceof NoSpecifiedEstimateReason and result = getMaxData()
+  }
+
   /**
    * Gets an upper bound to the amount of data that's being written (if one
    * can be found), except that float to string conversions are assumed to be
    * much smaller (8 bytes) than their true maximum length.  This can be
    * helpful in determining the cause of a buffer overflow issue.
    */
-  int getMaxDataLimited() { result = this.getMaxData() }
+  int getMaxDataLimited() { result = getMaxData() }
+
+  /**
+   * Gets an upper bound to the amount of data that's being written (if one
+   * can be found), specifying the reason for the estimation, except that
+   * float to string conversions are assumed to be much smaller (8 bytes)
+   * than their true maximum length.  This can be helpful in determining the
+   * cause of a buffer overflow issue.
+   */
+  int getMaxDataLimited(BufferWriteEstimationReason reason) { result = getMaxData(reason) }
 
   /**
    * Gets the size of a single character of the type this
@@ -135,10 +152,16 @@ class StrCopyBW extends BufferWriteCall {
     result = this.getArgument(this.getParamSize()).getValue().toInt() * this.getCharSize()
   }
 
-  override int getMaxData() {
+  private int getMaxDataImpl(BufferWriteEstimationReason reason) {
+    // when result exists, it is an exact flow analysis
+    reason instanceof ValueFlowAnalysis and
     result =
       this.getArgument(this.getParamSrc()).(AnalysedString).getMaxLength() * this.getCharSize()
   }
+
+  override int getMaxData(BufferWriteEstimationReason reason) { result = getMaxDataImpl(reason) }
+
+  override int getMaxData() { result = max(getMaxDataImpl(_)) }
 }
 
 /**
@@ -173,10 +196,16 @@ class StrCatBW extends BufferWriteCall {
     result = this.getArgument(this.getParamSize()).getValue().toInt() * this.getCharSize()
   }
 
-  override int getMaxData() {
+  private int getMaxDataImpl(BufferWriteEstimationReason reason) {
+    // when result exists, it is an exact flow analysis
+    reason instanceof ValueFlowAnalysis and
     result =
       this.getArgument(this.getParamSrc()).(AnalysedString).getMaxLength() * this.getCharSize()
   }
+
+  override int getMaxData(BufferWriteEstimationReason reason) { result = getMaxDataImpl(reason) }
+
+  override int getMaxData() { result = max(getMaxDataImpl(_)) }
 }
 
 /**
@@ -233,19 +262,29 @@ class SprintfBW extends BufferWriteCall {
 
   override Expr getDest() { result = this.getArgument(f.getOutputParameterIndex(false)) }
 
-  override int getMaxData() {
+  private int getMaxDataImpl(BufferWriteEstimationReason reason) {
     exists(FormatLiteral fl |
       fl = this.(FormattingFunctionCall).getFormat() and
-      result = fl.getMaxConvertedLength() * this.getCharSize()
+      result = fl.getMaxConvertedLengthWithReason(reason) * this.getCharSize()
     )
   }
 
-  override int getMaxDataLimited() {
+  override int getMaxData(BufferWriteEstimationReason reason) { result = getMaxDataImpl(reason) }
+
+  override int getMaxData() { result = max(getMaxDataImpl(_)) }
+
+  private int getMaxDataLimitedImpl(BufferWriteEstimationReason reason) {
     exists(FormatLiteral fl |
       fl = this.(FormattingFunctionCall).getFormat() and
-      result = fl.getMaxConvertedLengthLimited() * this.getCharSize()
+      result = fl.getMaxConvertedLengthLimitedWithReason(reason) * this.getCharSize()
     )
   }
+
+  override int getMaxDataLimited(BufferWriteEstimationReason reason) {
+    result = getMaxDataLimitedImpl(reason)
+  }
+
+  override int getMaxDataLimited() { result = max(getMaxDataLimitedImpl(_)) }
 }
 
 /**
@@ -336,19 +375,29 @@ class SnprintfBW extends BufferWriteCall {
     result = this.getArgument(this.getParamSize()).getValue().toInt() * this.getCharSize()
   }
 
-  override int getMaxData() {
+  private int getMaxDataImpl(BufferWriteEstimationReason reason) {
     exists(FormatLiteral fl |
       fl = this.(FormattingFunctionCall).getFormat() and
-      result = fl.getMaxConvertedLength() * this.getCharSize()
+      result = fl.getMaxConvertedLengthWithReason(reason) * this.getCharSize()
     )
   }
 
-  override int getMaxDataLimited() {
+  override int getMaxData(BufferWriteEstimationReason reason) { result = getMaxDataImpl(reason) }
+
+  override int getMaxData() { result = max(getMaxDataImpl(_)) }
+
+  private int getMaxDataLimitedImpl(BufferWriteEstimationReason reason) {
     exists(FormatLiteral fl |
       fl = this.(FormattingFunctionCall).getFormat() and
-      result = fl.getMaxConvertedLengthLimited() * this.getCharSize()
+      result = fl.getMaxConvertedLengthLimitedWithReason(reason) * this.getCharSize()
     )
   }
+
+  override int getMaxDataLimited(BufferWriteEstimationReason reason) {
+    result = getMaxDataLimitedImpl(reason)
+  }
+
+  override int getMaxDataLimited() { result = max(getMaxDataLimitedImpl(_)) }
 }
 
 /**
@@ -436,7 +485,9 @@ class ScanfBW extends BufferWrite {
 
   override Expr getDest() { result = this }
 
-  override int getMaxData() {
+  private int getMaxDataImpl(BufferWriteEstimationReason reason) {
+    // when this returns, it is based on exact flow analysis
+    reason instanceof ValueFlowAnalysis and
     exists(ScanfFunctionCall fc, ScanfFormatLiteral fl, int arg |
       this = fc.getArgument(arg) and
       fl = fc.getFormat() and
@@ -444,6 +495,10 @@ class ScanfBW extends BufferWrite {
     )
   }
 
+  override int getMaxData(BufferWriteEstimationReason reason) { result = getMaxDataImpl(reason) }
+
+  override int getMaxData() { result = max(getMaxDataImpl(_)) }
+
   override string getBWDesc() {
     exists(FunctionCall fc |
       this = fc.getArgument(_) and
@@ -474,8 +529,14 @@ class RealpathBW extends BufferWriteCall {
 
   override Expr getASource() { result = this.getArgument(0) }
 
-  override int getMaxData() {
+  private int getMaxDataImpl(BufferWriteEstimationReason reason) {
+    // although there may be some unknown invariants guaranteeing that a real path is shorter than PATH_MAX, we can consider providing less than PATH_MAX a problem with high precision
+    reason instanceof ValueFlowAnalysis and
     result = path_max() and
     this = this // Suppress a compiler warning
   }
+
+  override int getMaxData(BufferWriteEstimationReason reason) { result = getMaxDataImpl(reason) }
+
+  override int getMaxData() { result = max(getMaxDataImpl(_)) }
 }