Option 2: eliminates the AST→CFG bridge from the AST layer. Previously
'AstNode.getAFlowNode()' returned a 'ControlFlowNode' from the legacy
'Flow.qll' CFG via 'py_flow_bb_node' — this hardcoded the AST to know
about the legacy CFG, preventing files from cleanly switching to the
new shared CFG.
Removes:
* 'AstNode.getAFlowNode()' from 'AstExtended.qll'
* Type-narrowing overrides on 'Attribute' / 'Subscript' / 'Call' /
'IfExp' / 'Name' / 'NameConstant' / 'ImportMember' (in Exprs.qll
and Import.qll)
Rewrites ~130 call sites across 'python/ql/lib/' and 'python/ql/src/'
to bridge from the CFG side instead:
Before: node = expr.getAFlowNode()
After: node.getNode() = expr
Before: expr.getAFlowNode().(DefinitionNode).getValue()
After: exists(DefinitionNode d | d.getNode() = expr | d.getValue())
Before: cn.operands(const.getAFlowNode(), op, x)
After: exists(ControlFlowNode c | c.getNode() = const | cn.operands(c, op, x))
This is semantically a no-op — both forms are duals of the same predicate.
Verified by passing all library tests:
* 64 dataflow tests
* 28 ControlFlow + dataflow-new-ssa tests
* 1 essa SSA-compute test
* 93 tests total in the focused suite
Once committed, files that want to switch from the legacy 'Flow' CFG
to the new 'Cfg' facade only need to change their imports — the
bridge sites are CFG-side and respect whichever ControlFlowNode is in
scope.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
