Make AssignmentExpression matcher parenthesis-invariant on nested assignments#5859
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When an assignment is wrapped in ParenthesizedTree (e.g. int k = (a = b)), the checker previously did not look through the parentheses to determine the enclosing context, causing inconsistent behavior between int k = (a = b) and int k = a = b. Fix: unwrap ParenthesizedTree nodes before examining the parent context. The C-ism exemption ((a = getFoo()) != null) is checked before unwrapping so it still applies correctly. Fixes google#5827
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Description
Fixes #5827
The
AssignmentExpressionchecker'smatchAssignmentmethod was not parenthesis-invariant. When an assignment expression was wrapped inParenthesizedTree(e.g.int k = (a = b)), the checker did not look through the parentheses to determine the enclosing context. This caused the checker to miss the assignment, producing inconsistent results depending on whether parentheses were present.Fix
(a = getFoo()) != null) before unwrapping parentheses, so it still applies correctly.ParenthesizedTreenodes from the parent path before deciding whether the assignment is embedded in a larger expression.Before/After behavior
Before:
int k = (a = b)not flagged,int k = a = bflaggedAfter: Both forms flagged (paren-invariant)
C-ism
if ((a = getObject()) != null)still exempted (unchanged)Testing
parenthesizedAssignmentInDeclarationtest covering the paren-wrapped case