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56 lines
2.0 KiB
Plaintext
56 lines
2.0 KiB
Plaintext
/**
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* Compares the new-CFG SSA against the legacy ESSA on the same Python
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* sources. Reports definitions present in one implementation but not
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* the other, identified by variable name + source position.
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*
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* The `.expected` file records the current diff as a snapshot: as the
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* new SSA matures (closing captured-variable gap, exception bindings,
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* etc.) and tracks more variables, the snapshot should monotonically
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* shrink.
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*
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* Known categories of `def-only-old` mismatches:
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* - Function / class / global definitions with no in-scope read
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* (intentional: SSA is liveness-pruned, write-only variables are
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* not tracked).
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* - Captured / closure variables (if any remain; the new SSA inserts scope-entry
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* definitions for non-local reads, but legacy ESSA may still differ in corner cases).
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* - Module variables `__name__`, `__package__`, `$` (legacy ESSA
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* adds implicit bindings the new SSA does not).
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* - Exception-handler `as` bindings (depend on raise modeling).
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*
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* `def-only-new` mismatches would indicate the new SSA produces spurious
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* definitions; currently none are expected.
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*/
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import python
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import semmle.python.dataflow.new.internal.SsaImpl as NewSsa
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import semmle.python.controlflow.internal.Cfg as Cfg
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import semmle.python.essa.Essa
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string newDefSig(NewSsa::EssaNodeDefinition def) {
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exists(Cfg::ControlFlowNode n | n = def.getDefiningNode() |
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result =
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def.getVariable().getVariable().getId() + ":" + n.getLocation().getStartLine() + ":" +
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n.getLocation().getStartColumn()
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)
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}
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string legacyDefSig(EssaNodeDefinition def) {
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exists(ControlFlowNode n | n = def.getDefiningNode() |
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result =
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def.getSourceVariable().getName() + ":" + n.getLocation().getStartLine() + ":" +
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n.getLocation().getStartColumn()
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)
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}
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from string kind, string sig
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where
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kind = "def-only-new" and
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sig = newDefSig(_) and
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not sig = legacyDefSig(_)
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or
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kind = "def-only-old" and
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sig = legacyDefSig(_) and
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not sig = newDefSig(_)
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select kind, sig
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