Python: Don't prune any MatchLiteralPatterns
#18738
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Extends the mechanism introduced in #18030 to behave the same for _all_ `MatchLiteralPattern`s, not just the ones that happen to be the constant `True` or `False`. Co-authored-by: yoff <yoff@github.com>
Co-authored-by: yoff <yoff@github.com>
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PR Overview
This pull request extends the mechanism for pruning to ensure that no MatchLiteralPattern is ever pruned, avoiding the risk of misidentifying reachable code.
- The change notes have been updated to reflect the new behavior.
- The conditional check in the pruner for boolean literal patterns has been removed so that all MatchLiteralPatterns are processed uniformly.
Changes
| File | Description |
|---|---|
| python/ql/lib/change-notes/2025-02-11-fix-match-literal-pruning.md | Added notes to clarify that no MatchLiteralPattern is pruned |
| python/extractor/semmle/python/passes/pruner.py | Removed conditional pruning for boolean MatchLiteralPatterns to apply the fix universally |
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| category: fix | ||
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| - `MatchLiteralPattern`s are now never pruned, as this could lead to code being wrongly identified as unreachable. |
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Can we add an example so the reader knows what these look like in code?
Suggested change
| - `MatchLiteralPattern`s are now never pruned, as this could lead to code being wrongly identified as unreachable. | |
| - `MatchLiteralPattern`s such as `...` are now never pruned from the extracted source code. This fixes some situations where code was wrongly identified as unreachable. |
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Extends the mechanism introduced in #18030 to behave the same for all
MatchLiteralPatterns, not just the ones that happen to be the constantTrueorFalse.