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Python: qualify Flow.qll's AST references with Py:: prefix#21920

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Python: qualify Flow.qll's AST references with Py:: prefix#21920
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@yoff yoff commented Jun 1, 2026

Summary

Preparatory refactor for the shared-CFG dataflow migration (#21894).
Based on #21919 — merge that first.

Switches Flow.qll from import python to import python as Py, and qualifies every AST-class reference in the file with the Py:: prefix.

Why

The new CFG facade (introduced in a follow-up PR) wants to re-export many of the same names as python (e.g. ControlFlowNode, CallNode, BasicBlock), so consumers can import semmle.python.controlflow.Cfg instead of import python and pick up the new CFG. To make Flow.qll itself coexist cleanly with the new CFG and avoid ambiguities when both worlds are visible, the AST imports inside Flow.qll are namespaced under Py::.

Flow.qll's own CFG types (ControlFlowNode, BasicBlock, CallNode, NameNode, DefinitionNode, CompareNode, ...) keep their unqualified names — they remain the public CFG API exported from this file.

Semantic effect

None. The qualification was applied mechanically by script — every reference to an AST class (e.g. Expr, Bytes, Module, Scope, Call, Attribute, SsaVariable, AugAssign, Compare, BinaryExpr, etc.) was prefixed with Py::. No name resolution changes.

Verified by:

  • All 361 lib/ + src/ queries compile clean.
  • All 186 ControlFlow + PointsTo + dataflow library-tests pass.

Notes for reviewers

  • This PR is a single-file mechanical diff. Easiest to review with git diff --word-diff-regex='[A-Za-z_]+'.

Copilot AI review requested due to automatic review settings June 1, 2026 11:22
@yoff yoff requested a review from a team as a code owner June 1, 2026 11:22
@github-actions github-actions Bot added the Python label Jun 1, 2026
Copilot AI reviewed Jun 1, 2026
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Pull request overview

Refactors semmle.python.Flow to avoid future name collisions during the shared-CFG dataflow migration by importing the Python AST module as Py and qualifying AST-type references accordingly, while keeping Flow’s CFG-facing API names unqualified.

Changes:

  • Replaces import python with import python as Py.
  • Qualifies AST-related references throughout Flow.qll with Py:: to reduce ambiguity when new CFG facade types are introduced.
Show a summary per file
File Description
python/ql/lib/semmle/python/Flow.qll Switches to import python as Py and qualifies Python AST references with Py:: to prevent naming conflicts ahead of shared-CFG migration.

Copilot's findings

  • Files reviewed: 1/1 changed files
  • Comments generated: 2

Comment thread python/ql/lib/semmle/python/Flow.qll Outdated
Comment thread python/ql/lib/semmle/python/Flow.qll Outdated
@yoff yoff added the no-change-note-required This PR does not need a change note label Jun 1, 2026
This was referenced Jun 1, 2026
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yoff pushed a commit that referenced this pull request Jun 1, 2026
@yoff
Python: switch dataflow library to new (shared) CFG + SSA
4304ddb 
Flips the Python dataflow trunk from the legacy CFG (semmle/python/Flow.qll)
and legacy ESSA SSA (semmle/python/essa/*) to the new shared CFG facade
(semmle.python.controlflow.internal.Cfg) and the new SSA adapter
(semmle.python.dataflow.new.internal.SsaImpl), both introduced
additively in the preceding PRs in this stack.

This is the trunk-flip equivalent of the original draft PR #21894 (kept
around as documentation), rebased on top of the four preparatory PRs:

  P1: Remove AstNode.getAFlowNode() and rewrite callers (#21919).
  P2: Qualify Flow.qll's AST references with Py:: prefix (#21920).
  P3: Add new shared-CFG-backed control flow graph (#21921).
  P4: Add new shared-SSA-backed SSA adapter (#21923).

The Python dataflow library (semmle/python/dataflow/new/) now imports
the new CFG facade and SSA adapter. All CFG-typed predicates
(ControlFlowNode, CallNode, BasicBlock, NameNode, AttrNode, ...) are
qualified with the Cfg:: prefix; SSA references switch from
EssaVariable/EssaDefinition to SsaImpl::Definition/SourceVariable.

GuardNode is redesigned to use the new CFG's outcome-node model
(isAfterTrue / isAfterFalse) instead of the legacy ConditionBlock +
flipped indirection. Only BarrierGuard<...> is preserved as public
API.

Framework files (Bottle, FastApi, Django, Tornado, Pyramid, Stdlib,
...) are updated to take CFG nodes from the new facade.

A handful of dataflow consistency tweaks for the new CFG:
- Augmented-assignment targets are treated as both load and store.
- 'from X import *' produces uncertain SSA writes for unknown names.
- CFG nodes are canonicalised so dataflow does not see equivalent
  pre/post-order pairs as distinct nodes.

Two AST tweaks for the new CFG:
- AstNodeImpl: omit PEP 695 type-parameter names from
  FunctionDefExpr / ClassDefExpr children.
- ImportResolution: drop the legacy essa import.

Test churn (~175 files): reblessed library- and query-test .expected
files reflect slightly different CFG granularity, different toString
output, and a handful of true alert deltas in security queries.

Verification: all 367 lib + src + consistency-queries compile clean.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
yoff pushed a commit that referenced this pull request Jun 1, 2026
@yoff
Python: switch dataflow library to new (shared) CFG + SSA
5187e9a 
Flips the Python dataflow trunk from the legacy CFG (semmle/python/Flow.qll)
and legacy ESSA SSA (semmle/python/essa/*) to the new shared CFG facade
(semmle.python.controlflow.internal.Cfg) and the new SSA adapter
(semmle.python.dataflow.new.internal.SsaImpl), both introduced
additively in the preceding PRs in this stack.

This is the trunk-flip equivalent of the original draft PR #21894 (kept
around as documentation), rebased on top of the four preparatory PRs:

  P1: Remove AstNode.getAFlowNode() and rewrite callers (#21919).
  P2: Qualify Flow.qll's AST references with Py:: prefix (#21920).
  P3: Add new shared-CFG-backed control flow graph (#21921).
  P4: Add new shared-SSA-backed SSA adapter (#21923).

The Python dataflow library (semmle/python/dataflow/new/) now imports
the new CFG facade and SSA adapter. All CFG-typed predicates
(ControlFlowNode, CallNode, BasicBlock, NameNode, AttrNode, ...) are
qualified with the Cfg:: prefix; SSA references switch from
EssaVariable/EssaDefinition to SsaImpl::Definition/SourceVariable.

GuardNode is redesigned to use the new CFG's outcome-node model
(isAfterTrue / isAfterFalse) instead of the legacy ConditionBlock +
flipped indirection. Only BarrierGuard<...> is preserved as public
API.

Framework files (Bottle, FastApi, Django, Tornado, Pyramid, Stdlib,
...) are updated to take CFG nodes from the new facade.

A handful of dataflow consistency tweaks for the new CFG:
- Augmented-assignment targets are treated as both load and store.
- 'from X import *' produces uncertain SSA writes for unknown names.
- CFG nodes are canonicalised so dataflow does not see equivalent
  pre/post-order pairs as distinct nodes.

Two AST tweaks for the new CFG:
- AstNodeImpl: omit PEP 695 type-parameter names from
  FunctionDefExpr / ClassDefExpr children.
- ImportResolution: drop the legacy essa import.

Test churn (~175 files): reblessed library- and query-test .expected
files reflect slightly different CFG granularity, different toString
output, and a handful of true alert deltas in security queries.

Verification: all 367 lib + src + consistency-queries compile clean.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
yoff pushed a commit that referenced this pull request Jun 1, 2026
@yoff
Python: switch dataflow library to new (shared) CFG + SSA
8178a8d 
Flips the Python dataflow trunk from the legacy CFG (semmle/python/Flow.qll)
and legacy ESSA SSA (semmle/python/essa/*) to the new shared CFG facade
(semmle.python.controlflow.internal.Cfg) and the new SSA adapter
(semmle.python.dataflow.new.internal.SsaImpl), both introduced
additively in the preceding PRs in this stack.

This is the trunk-flip equivalent of the original draft PR #21894 (kept
around as documentation), rebased on top of the four preparatory PRs:

  P1: Remove AstNode.getAFlowNode() and rewrite callers (#21919).
  P2: Qualify Flow.qll's AST references with Py:: prefix (#21920).
  P3: Add new shared-CFG-backed control flow graph (#21921).
  P4: Add new shared-SSA-backed SSA adapter (#21923).

The Python dataflow library (semmle/python/dataflow/new/) now imports
the new CFG facade and SSA adapter. All CFG-typed predicates
(ControlFlowNode, CallNode, BasicBlock, NameNode, AttrNode, ...) are
qualified with the Cfg:: prefix; SSA references switch from
EssaVariable/EssaDefinition to SsaImpl::Definition/SourceVariable.

GuardNode is redesigned to use the new CFG's outcome-node model
(isAfterTrue / isAfterFalse) instead of the legacy ConditionBlock +
flipped indirection. Only BarrierGuard<...> is preserved as public
API.

Framework files (Bottle, FastApi, Django, Tornado, Pyramid, Stdlib,
...) are updated to take CFG nodes from the new facade.

A handful of dataflow consistency tweaks for the new CFG:
- Augmented-assignment targets are treated as both load and store.
- 'from X import *' produces uncertain SSA writes for unknown names.
- CFG nodes are canonicalised so dataflow does not see equivalent
  pre/post-order pairs as distinct nodes.

Two AST tweaks for the new CFG:
- AstNodeImpl: omit PEP 695 type-parameter names from
  FunctionDefExpr / ClassDefExpr children.
- ImportResolution: drop the legacy essa import.

Test churn (~175 files): reblessed library- and query-test .expected
files reflect slightly different CFG granularity, different toString
output, and a handful of true alert deltas in security queries.

Verification: all 367 lib + src + consistency-queries compile clean.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@yoff yoff force-pushed the yoff/python-flow-py-namespace branch from 6bed86e to 73f9a1b Compare June 1, 2026 13:27
yoff pushed a commit that referenced this pull request Jun 1, 2026
@yoff
Python: switch dataflow library to new (shared) CFG + SSA
8ecea67 
Flips the Python dataflow trunk from the legacy CFG (semmle/python/Flow.qll)
and legacy ESSA SSA (semmle/python/essa/*) to the new shared CFG facade
(semmle.python.controlflow.internal.Cfg) and the new SSA adapter
(semmle.python.dataflow.new.internal.SsaImpl), both introduced
additively in the preceding PRs in this stack.

This is the trunk-flip equivalent of the original draft PR #21894 (kept
around as documentation), rebased on top of the four preparatory PRs:

  P1: Remove AstNode.getAFlowNode() and rewrite callers (#21919).
  P2: Qualify Flow.qll's AST references with Py:: prefix (#21920).
  P3: Add new shared-CFG-backed control flow graph (#21921).
  P4: Add new shared-SSA-backed SSA adapter (#21923).

The Python dataflow library (semmle/python/dataflow/new/) now imports
the new CFG facade and SSA adapter. All CFG-typed predicates
(ControlFlowNode, CallNode, BasicBlock, NameNode, AttrNode, ...) are
qualified with the Cfg:: prefix; SSA references switch from
EssaVariable/EssaDefinition to SsaImpl::Definition/SourceVariable.

GuardNode is redesigned to use the new CFG's outcome-node model
(isAfterTrue / isAfterFalse) instead of the legacy ConditionBlock +
flipped indirection. Only BarrierGuard<...> is preserved as public
API.

Framework files (Bottle, FastApi, Django, Tornado, Pyramid, Stdlib,
...) are updated to take CFG nodes from the new facade.

A handful of dataflow consistency tweaks for the new CFG:
- Augmented-assignment targets are treated as both load and store.
- 'from X import *' produces uncertain SSA writes for unknown names.
- CFG nodes are canonicalised so dataflow does not see equivalent
  pre/post-order pairs as distinct nodes.

Two AST tweaks for the new CFG:
- AstNodeImpl: omit PEP 695 type-parameter names from
  FunctionDefExpr / ClassDefExpr children.
- ImportResolution: drop the legacy essa import.

Test churn (~175 files): reblessed library- and query-test .expected
files reflect slightly different CFG granularity, different toString
output, and a handful of true alert deltas in security queries.

Verification: all 367 lib + src + consistency-queries compile clean.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@yoff yoff mentioned this pull request Jun 1, 2026
Open
@yoff yoff force-pushed the yoff/python-remove-getAFlowNode branch from befb51a to 8e4f127 Compare June 1, 2026 14:05
Copilot AI and others added 2 commits June 1, 2026 14:05
@yoff
Python: qualify Flow.qll's AST references with Py:: prefix
b8daa24 
Preparatory refactor for the shared-CFG dataflow migration. Switches
'import python' to 'import python as Py' inside Flow.qll, and qualifies
every AST-class reference (Expr, Bytes, Dict, AssignExpr, Compare,
Module, Scope, Call, Attribute, SsaVariable, AugAssign, etc.) with the
Py:: prefix.

Flow.qll's own CFG types (ControlFlowNode, BasicBlock, CallNode,
NameNode, DefinitionNode, CompareNode, ...) keep their unqualified
names — they remain the public CFG API exported from this file.

This is a semantic noop: the qualification was applied mechanically by
script and no name resolution changes. Verified by:
- All 361 lib/ + src/ queries compile clean.
- All 186 ControlFlow + PointsTo + dataflow library-tests pass.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@yoff
Apply suggestions from code review
709a4a3 
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
@yoff yoff force-pushed the yoff/python-flow-py-namespace branch from 73f9a1b to 709a4a3 Compare June 1, 2026 14:05
tausbn
tausbn approved these changes Jun 1, 2026
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Looks reasonable to me. 👍

yoff pushed a commit that referenced this pull request Jun 1, 2026
@yoff
Python: switch dataflow library to new (shared) CFG + SSA
c476e5a 
Flips the Python dataflow trunk from the legacy CFG (semmle/python/Flow.qll)
and legacy ESSA SSA (semmle/python/essa/*) to the new shared CFG facade
(semmle.python.controlflow.internal.Cfg) and the new SSA adapter
(semmle.python.dataflow.new.internal.SsaImpl), both introduced
additively in the preceding PRs in this stack.

This is the trunk-flip equivalent of the original draft PR #21894 (kept
around as documentation), rebased on top of the four preparatory PRs:

  P1: Remove AstNode.getAFlowNode() and rewrite callers (#21919).
  P2: Qualify Flow.qll's AST references with Py:: prefix (#21920).
  P3: Add new shared-CFG-backed control flow graph (#21921).
  P4: Add new shared-SSA-backed SSA adapter (#21923).

The Python dataflow library (semmle/python/dataflow/new/) now imports
the new CFG facade and SSA adapter. All CFG-typed predicates
(ControlFlowNode, CallNode, BasicBlock, NameNode, AttrNode, ...) are
qualified with the Cfg:: prefix; SSA references switch from
EssaVariable/EssaDefinition to SsaImpl::Definition/SourceVariable.

GuardNode is redesigned to use the new CFG's outcome-node model
(isAfterTrue / isAfterFalse) instead of the legacy ConditionBlock +
flipped indirection. Only BarrierGuard<...> is preserved as public
API.

Framework files (Bottle, FastApi, Django, Tornado, Pyramid, Stdlib,
...) are updated to take CFG nodes from the new facade.

A handful of dataflow consistency tweaks for the new CFG:
- Augmented-assignment targets are treated as both load and store.
- 'from X import *' produces uncertain SSA writes for unknown names.
- CFG nodes are canonicalised so dataflow does not see equivalent
  pre/post-order pairs as distinct nodes.

Two AST tweaks for the new CFG:
- AstNodeImpl: omit PEP 695 type-parameter names from
  FunctionDefExpr / ClassDefExpr children.
- ImportResolution: drop the legacy essa import.

Test churn (~175 files): reblessed library- and query-test .expected
files reflect slightly different CFG granularity, different toString
output, and a handful of true alert deltas in security queries.

Verification: all 367 lib + src + consistency-queries compile clean.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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