Fix #13563: Closure / Arrow functions type difference when an array is reset#4904
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Fix #13563: Closure / Arrow functions type difference when an array is reset#4904phpstan-bot wants to merge 2 commits into2.1.xfrom
phpstan-bot wants to merge 2 commits into2.1.xfrom
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…nt scope
- Arrow functions incorrectly preserved narrowed property types on $this from the
parent scope (e.g. after $this->dates = [], the arrow function saw array{} instead
of the PHPDoc type array<int, DateTime>)
- Added invalidateNonReadonlyThisPropertyFetches() to MutatingScope that removes
non-readonly $this property fetch expression types, matching closure behavior
- Updated TemplateTypeTrait::describe() to use a local variable instead of $this->default
inside an arrow function, avoiding the now-correctly-invalidated property narrowing
- New regression test in tests/PHPStan/Analyser/nsrt/bug-13563.php
Fixes phpstan/phpstan#13563
Closes phpstan/phpstan#12912 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Arrow functions incorrectly inherited narrowed
$thisproperty types from the parent scope. After$this->dates = [](wheredateshas PHPDoc typearray<int, DateTime>), an arrow function would see$this->datesasarray{}instead ofarray<int, DateTime>. Closures already correctly dropped this narrowing. This fix brings arrow function behavior in line with closures for$thisproperty type tracking.Changes
invalidateNonReadonlyThisPropertyFetches()method tosrc/Analyser/MutatingScope.phpthat filters out non-readonly$this->propertyexpression type holdersenterArrowFunctionWithoutReflection()insrc/Analyser/MutatingScope.phpto call this method for both expression types and native expression types when$thisis available and the arrow function is not staticsrc/Type/Generic/TemplateTypeTrait.phpto assign$this->defaultto a local variable before using it in an arrow function, since the property narrowing from the!== nullcheck is no longer preserved inside arrow functions (matching closure behavior)Root cause
enterArrowFunctionWithoutReflection()started with$arrowFunctionScope = $this, inheriting ALL expression types from the parent scope including narrowed property types on$this. In contrast,enterAnonymousFunctionWithoutReflection()(for closures) builds expression types from scratch and only preserves readonly property fetches on$this(lines 2762-2776). Since both closures and arrow functions may be invoked later when properties could have been modified, they should both drop non-readonly$thisproperty narrowing.Test
Added
tests/PHPStan/Analyser/nsrt/bug-13563.phpwhich verifies that both arrow functions and closures resolve$this->datestoarray<int, DateTime>(the PHPDoc type) after$this->dates = [], rather thanarray{}(the narrowed empty array type).Fixes phpstan/phpstan#13563
Closes phpstan/phpstan#12912