Fix phpstan/phpstan#3585: Reassignment of $this is not an error#5146
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VincentLanglet merged 4 commits intophpstan:2.1.xfrom Mar 8, 2026
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- Added $this reassignment check to InvalidAssignVarRule - Handles direct assignment ($this = ...), compound assignment ($this .= ...), and destructuring ([$this] = ...) - Error is reported in all contexts (instance methods, static methods, functions) - New regression test in tests/PHPStan/Rules/Operators/data/bug-3585.php Closes phpstan/phpstan#3585
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Playing with it I found a similar error with https://3v4l.org/1rJJM#veol (Which can be considered a separate issue) |
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It's another issue to me indeed. works fine. Your example is about variable for the parameter, which should be a different rule from the InvalidAssign one (which is about Same will exist for this |
staabm
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Mar 8, 2026
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I think it requires your review @ondrejmirtes since we're introducing a new error (?) |
ondrejmirtes
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Mar 8, 2026
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created a new issue for it |
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Mar 9, 2026
…tan#5146) Co-authored-by: VincentLanglet <[email protected]> Co-authored-by: Vincent Langlet <[email protected]>
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Summary
PHP reports a fatal error (
Cannot re-assign $this) when$thisis used as an assignment target, but PHPStan did not report any error. This PR adds a check toInvalidAssignVarRuleto detect and report$thisreassignment.Changes
tests/PHPStan/Rules/Operators/data/bug-3585.phptestBug3585inInvalidAssignVarRuleTestRoot cause
The
InvalidAssignVarRulealready validated assignment targets for nullsafe operators and non-assignable expressions, but had no check for the special$thispseudo-variable. PHP itself prevents$thisreassignment at the parser/compiler level, so PHPStan needs to replicate this check.Test
The regression test covers
$thisreassignment in:All cases expect the error "Cannot re-assign $this." to be reported.
Fixes phpstan/phpstan#3585