hohn/codeql
1
0
Fork 0
mirror of https://github.com/github/codeql.git synced 2026-08-05 18:03:27 +02:00
Code Issues Packages Projects Releases Wiki Activity
Files
yoff/python-cfg-modelling-exceptions
codeql/python/ql/lib/change-notes/2026-05-19-add-shared-cfg.md
Copilot 9cdeb8e7ee Python: add new shared-CFG-backed control flow graph 
Preparatory refactor for the shared-CFG dataflow migration. Adds the
new Python CFG library additively, without changing any production
behaviour.

Library additions:

- semmle.python.controlflow.internal.AstNodeImpl — mediates between
  the Python AST and the shared codeql.controlflow.ControlFlowGraph
  signature. Wraps Python's Stmt/Expr/Scope/Pattern and adds two
  synthetic kinds of node (BlockStmt for body slots, intermediate
  nodes for multi-operand boolean expressions).

- semmle.python.controlflow.internal.Cfg — public facade
  re-exposing the same API surface as semmle/python/Flow.qll
  (ControlFlowNode, CallNode, BasicBlock, NameNode, DefinitionNode,
  CompareNode, ...), backed by the shared CFG.

- lib/printCfgNew.ql — debug/visualisation query for the new CFG.

- consistency-queries/CfgConsistency.ql — consistency query running
  the shared CFG's standard checks against Python.

Shared library:

- shared.controlflow.ControlFlowGraph — adds two defaulted
  getWhileElse / getForeachElse predicates to AstSig so Python can
  model while-else / for-else (no behavioural change for other
  languages).

Test additions:

- ControlFlow/bindings/* — annotation-driven SSA-binding tests for
  the new CFG (annassign, compound, comprehension, decorated,
  except_handler, imports, match_pattern, parameters, simple,
  type_params, walrus_starred, with_stmt, dead_under_no_raise).

- ControlFlow/store-load/* — basic store/load coverage.

- ControlFlow/evaluation-order/NewCfg*.ql — mirrors of the existing
  OldCfg evaluation-order self-validation suite, run against the
  new CFG via NewCfgImpl.qll.

- Minor extensions to existing test_if.py / test_boolean.py +
  cosmetic .expected churn on a handful of OldCfg tests.

No dataflow, SSA, or production query is migrated yet — that lands in
follow-up PRs. The new CFG library has zero callers in lib/ and src/.

Verified by:
- All lib + src + consistency-queries compile clean (367 queries).
- All 56 ControlFlow library-tests pass.
- All 474 dataflow + PointsTo library-tests + consistency tests pass.
- syntax_error/CONSISTENCY/CfgConsistency passes.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-06-22 13:38:30 +00:00

439 B
Raw Permalink Blame History

category
category
minorAnalysis
  • A new Python control flow graph implementation has been added under semmle.python.controlflow.internal.Cfg (backed by AstNodeImpl.qll), built on the shared codeql.controlflow.ControlFlowGraph library. It is not yet used by the dataflow library or any production query; the legacy CFG in semmle/python/Flow.qll remains the default. The new library is exposed for tests and for upcoming migrations.