Summary

Fixes a false positive property.unusedType error when a nullable generic property (e.g., ?WeakMap) is assigned new WeakMap() inside a null check like if ($this->map === null). This regression was introduced in 1.12.4 by PR #3364.

Changes

• Modified src/Analyser/ExprHandler/NewHandler.php to resolve the declared property type from reflection instead of using the scope-narrowed type
• Added resolveAssignedPropertyDeclaredType() helper method that handles both instance and static property fetches
• Added regression test tests/PHPStan/Rules/TooWideTypehints/data/bug-11844.php covering static properties, instance properties, and direct assignment

Root cause

When new WeakMap() is assigned to a property inside a null check (if ($this->map === null)), the scope has already narrowed the property type to null. The NewHandler::exactInstantiation() method used $scope->getType($assignedToProperty) to infer generic types from the property, but this returned the narrowed type (null) instead of the declared type (WeakMap<object, string>|null). After TypeCombinator::removeNull(), this became never, causing TooWideTypeCheck to incorrectly conclude that WeakMap<object, string> was never assigned.

The fix resolves the property reflection directly and uses getReadableType() to get the declared type, which is unaffected by scope narrowing.

Test

Added tests/PHPStan/Rules/TooWideTypehints/data/bug-11844.php with three test cases:

• Static nullable WeakMap property assigned inside null check (original report)
• Instance nullable WeakMap property assigned inside null check
• Direct assignment without null check (was already working)

All three should produce zero property.unusedType errors.

Fixes phpstan/phpstan#11844