Preparatory refactor for the shared-CFG dataflow migration.
Deprecates the AstNode.getAFlowNode() cached predicate on the public
Python QL API and rewrites all ~140 internal callers across lib/, src/,
test/, and tools/ from `expr.getAFlowNode() = cfgNode` to
`cfgNode.getNode() = expr`, using ControlFlowNode.getNode() which
already exists in Flow.qll.
The predicate itself is preserved (with a deprecation note pointing at
the new pattern) so external users do not experience churn — they can
migrate at their own pace and the AST/CFG hierarchies still get the
intended untangling once the deprecation eventually elapses.
Semantic noop verified by:
- All 361 lib/ + src/ queries compile clean.
- All 122 ControlFlow + PointsTo library-tests pass.
- All 64 dataflow library-tests pass.
- All 113 Variables/Exceptions/Expressions/Statements/Functions/Imports/
Security/CWE-798/ModificationOfParameterWithDefault query-tests pass.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Moves the classes/predicates that _actually_ depend on points-to to the
`LegacyPointsTo` module, leaving behind a module that contains all of
the metrics-related stuff (line counts, nesting depth, etc.) that don't
need points-to to be evaluated.
Consequently, `Metrics` is now no longer a private import in
`python.qll`.
Gets rid of the `getMetrics` methods on the `Function`, `Class`, and
`Module` classes. To access the metrics, one must first import the
`LegacyPointsTo` module, and then either change the type to
`{Function,Class,Module}Metrics` or cast to the appropriate type.
Turns out the `ImportTime` module (despite living in
`semmle.python.types` does not actually depend on points-to, so some of
the `LegacyPointsTo` imports could be replaced or removed.
Gets rid of a bunch of predicates relating to reachability (which
depended on the modelling of exceptions, which uses points-to), moving
them to `LegacyPointsTo`. In the process, we gained a new class
`BasicBlockWithPointsTo`.
This frees `Class.qll`, `Exprs.qll`, and `Function.qll` from the
clutches of points-to. For the somewhat complicated setup with
`getLiteralObject` (an abstract method), I opted for a slightly ugly but
workable solution of just defining a predicate on `ImmutableLiteral`
that inlines each predicate body, special-cased to the specific instance
to which it applies.
For now, these have just been made into `private` imports. After doing
this, I went through all of the (now not compiling) files and added in
private imports to the modules that they actually depended on.
I also added an explicit import of `LegacyPointsTo` (even though it may
be unnecessary) in cases where the points-to dependency was somewhat
surprising (and one we want to get rid of). This was primarily inside
the various SSA layers.
For modules inside `semmle.python.{types, objects, pointsto}` I did not
bother, as these are fairly clearly related to points-to.
Moves the existing points-to predicates to the newly added class
`ControlFlowNodeWithPointsTo` which resides in the `LegacyPointsTo`
module.
(Existing code that uses these predicates should import this module, and
references to `ControlFlowNode` should be changed to
`ControlFlowNodeWithPointsTo`.)
Also updates all existing points-to based code to do just this.
