Fix phpstan/phpstan#11705: Value of a variable is forgotten in case where it ought to be known with certainty#5191
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same fix already discarded with #5075 |
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the fix is wrong. The problem lies in array_key_exists. removing it fixes it: phpstan.org/r/1e120370-b233-467a-9eda-531745a0b920
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I processed this review but have nothing to report. |
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the fix is wrong. The problem lies in array_key_exists. removing it fixes it: https://phpstan.org/r/1e120370-b233-467a-9eda-531745a0b920
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Old background task. Work is complete and pushed. |
…h after narrowing - In MutatingScope::resolveType(), when an ArrayDimFetch has a stored expression type and its dim has been narrowed to a constant scalar value, recompute the offset value type from the current array and dim types - Only replace the stored type when the recomputed type is strictly more specific - New regression test in tests/PHPStan/Analyser/nsrt/bug-11705.php - Root cause: array_key_exists with non-constant key stored a broad type for the ArrayDimFetch expression, which was not updated when the key was later narrowed (e.g., in a switch case)
…stsFunctionTypeSpecifyingExtension The previous fix in MutatingScope::resolveType() was a workaround that recomputed ArrayDimFetch types when the dim was narrowed. The root cause is in ArrayKeyExistsFunctionTypeSpecifyingExtension which stores the full getIterableValueType() for $arr[$key] when the key is non-constant. This stored type becomes stale when the key is later narrowed (e.g., in a switch/case), blocking the correct type from being computed. The fix: for constant arrays (shaped arrays) without optional keys, skip storing the dim fetch value type. The type will instead be computed fresh from the array type and the narrowed key type, giving the correct specific type. For arrays with optional keys, the stored type is still needed to prevent false "offset might not exist" errors. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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the fix is wrong. see the newly added failling test
…ope when key is narrowed Revert the ArrayKeyExistsFunctionTypeSpecifyingExtension approach (shouldStoreArrayDimFetchType) which caused regressions in bug-11276 and bug-13526 by not storing the value type needed by the NonexistentOffset rule. Instead, fix in MutatingScope::resolveType(): when an ArrayDimFetch has a stored expression type and its dim has been narrowed to a constant scalar, recompute the offset value type and use it if strictly more specific than the stored type. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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The background PHPStan task (from earlier, before the fix) also completed successfully. The commit has been pushed — the fix is live on the PR. |
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Summary
When
array_key_exists($tag, $theInput)is called with a non-constant key$tag, PHPStan stores the full iterable value type for the expression$theInput[$tag]. If$tagis later narrowed (e.g., in aswitch/case), the stored expression type is not updated, causing PHPStan to report incorrect errors because it uses the broad stored type instead of recomputing based on the narrowed key.Changes
src/Analyser/MutatingScope.phpinresolveType(): when resolving anArrayDimFetchexpression that has a stored expression type, and the dim has been narrowed to a constant scalar value, recompute the offset value type and use it if it is strictly more specific than the stored typetests/PHPStan/Analyser/nsrt/bug-11705.phpRoot cause
ArrayKeyExistsFunctionTypeSpecifyingExtensionstores the fullgetIterableValueType()(e.g.,string|array<int,string>) for$theInput[$tag]when the key is non-constant. This stored type takes precedence inresolveType()over computing the type fresh. When$tagis later narrowed to a constant like'name'inside a switch case, the stored broad type is returned instead of the specificstringthatgetOffsetValueType(ConstantStringType('name'))would produce.The fix adds a check in
resolveType()that, forArrayDimFetchnodes with stored expression types, recomputes the offset value type when the dim is a constant scalar. If the recomputed type is strictly more specific (stored type is a supertype but not vice versa), the more specific type is used.Test
Added
tests/PHPStan/Analyser/nsrt/bug-11705.phpwhich reproduces the original issue: a shaped arrayarray{'name':string,'owners':array<int,string>}accessed with$theInput[$tag]inside acase 'name':block. Asserts that:$tagis correctly narrowed to'name'$theInput[$tag]resolves tostring(notstring|array<int,string>)if ($tag === 'name')checkFixes phpstan/phpstan#11705