Don't suggest collapsible_match guard when condition mutates pattern binding#16869
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JasmineLCY wants to merge 1 commit intorust-lang:masterfrom
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Don't suggest collapsible_match guard when condition mutates pattern binding#16869JasmineLCY wants to merge 1 commit intorust-lang:masterfrom
collapsible_match guard when condition mutates pattern binding#16869JasmineLCY wants to merge 1 commit intorust-lang:masterfrom
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…n binding When `mutated_variables` returns `None` (cannot determine mutations), `pat_bindings_moved_or_mutated` silently ignored the result instead of conservatively bailing out. This caused the lint to suggest match guards for expressions that require mutable access to pattern bindings, which is forbidden in guards. Fixes rust-lang#16864
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r? @llogiq rustbot has assigned @llogiq. Use Why was this reviewer chosen?The reviewer was selected based on:
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Please claim the issue you want to fix so that nobody works on it as well, and remove the issue number from the commit message as indicated in #16869 (comment) |
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Apologies for the delayed response. Will claim the issue and fix the commit message. |
llogiq
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Apr 24, 2026
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When
mutated_variablesreturnsNone(cannot determine mutations),pat_bindings_moved_or_mutatedsilently ignored the result instead of conservatively bailing out. This caused the lint to suggest match guards for expressions that require mutable access to pattern bindings, which is forbidden in guards — variables are immutable in pattern guards.The fix changes the
if let Some(mutated)tolet Some(mutated) ... else { return true }, matching the existing conservative bail-out forExprUseVisitorerrors a few lines above.Fixes #16864
changelog: Fix [
collapsible_match] suggesting a match guard when the condition mutates a pattern bindingDrafted with AI assistance. Reviewed, tested, and verified by me.