Fix phpstan/phpstan#13023: function.alreadyNarrowedType and function.impossibleType after updates to 2.1.15#5184
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- When analyzing trait methods, $this is bound to each using class separately - is_a($this, SomeClass::class) was reported as "always true" in SomeClass context and "always false" in SomeClass2 context, but both are false positives - Added trait-aware check in ImpossibleCheckTypeHelper to treat $this as uncertain when inside a trait, since the same code is shared across multiple classes - New regression test in tests/PHPStan/Rules/Comparison/data/bug-13023.php Closes phpstan/phpstan#13023
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Summary
When a trait method uses
is_a($this, SomeClass::class), PHPStan analyzes the method once per class that uses the trait. This caused false positives: in the context ofSomeClassit reported "always true" (function.alreadyNarrowedType), and in the context ofSomeClass2it reported "always false" (function.impossibleType). Both are incorrect since the trait code is shared across multiple classes.Changes
src/Rules/Comparison/ImpossibleCheckTypeHelper.phpto treat$thisas having uncertain type when inside a trait context, in both thesureTypesandsureNotTypesloopstests/PHPStan/Rules/Comparison/data/bug-13023.phptestBug13023intests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.phpRoot cause
ImpossibleCheckTypeHelper::findSpecifiedType()compares the result type from the type specifier against the argument type from the scope. When analyzing a trait method,$thisis typed asThisTypebound to the specific using class. TheisSuperTypeOfcheck then returns a definitive yes/no for each class context, causing the rule to report false positives. The fix detects when we're in a trait and the expression being checked is$this, and treats the result asmaybeinstead.Test
Added a regression test with a trait
MyTraitused by bothSomeClassandSomeClass2, where the trait method callsis_a($this, SomeClass::class). The test expects no errors.Fixes phpstan/phpstan#13023