Fix phpstan/phpstan#14459: Null coalescing operator does not report redundant left operand when always defined

[phpstan-bot]

Summary

PHPStan did not report redundant usage of ?? (and isset()/empty()) when the left-hand side was a promoted readonly property that is always defined and non-nullable. For example, $dto->policyholderId ?? $dto->payerId where policyholderId is public readonly \stdClass was not flagged.

Changes

• src/Rules/IssetCheck.php: Added condition to not bail early when a property is promoted AND (readonly OR hooked) — these properties are always initialized and cannot be unset, so the isset/coalesce check should proceed to report the redundancy.
• src/Analyser/MutatingScope.php: Mirrored the same fix in issetCheck() as the codebase convention requires (comment: "mirrored in PHPStan\Rules\IssetCheck").
• tests/PHPStan/Rules/Variables/data/bug-14459.php: New test data file.
• tests/PHPStan/Rules/Variables/NullCoalesceRuleTest.php: New test method testBug14459.

Root cause

In IssetCheck::check(), when processing a property fetch that isn't $this->prop, the code checks if the property has an expression type in scope. If not, it checks hasDefaultValue() — promoted readonly properties return false for this (they get their value from the constructor parameter, not a default). This caused the method to return null (no error) even though the property is guaranteed to be initialized and cannot be unset.

The fix adds an additional condition: if the property is promoted AND (readonly OR has hooks), skip the early return and let the error reporting proceed normally.

Test

The regression test covers four scenarios:

1. Promoted readonly non-nullable (public readonly \stdClass $policyholderId) — expects error: "is not nullable"
2. Promoted readonly nullable (public readonly ?\stdClass $nullablePolicyholderId) — no error expected (nullable, so ?? is valid)
3. Promoted non-readonly (public \stdClass $payerId) — no error expected (can be unset())
4. Non-promoted readonly (public readonly \stdClass $payerId with manual constructor assignment) — no error expected (might be uninitialized)

Fixes phpstan/phpstan#14459

[ondrejmirtes]

1. Hooks don't have a test case. It has to be a separate method with RequiresPhp >= 8.4.
2. I don't love && !($nativeReflection->isPromoted() && ($nativeReflection->isReadOnly() || $nativeReflection->isHooked())). Rather, it should be && (!$nativeReflection->isPromoted() || (!$nativeReflection->isReadOnly() && !$nativeReflection->isHooked()))

[phpstan-bot]

Both commits have been pushed. Here's a summary of the changes made to address the review:

1. Refactored boolean condition (reviewer feedback SoapClient - fixed signature map for SoapClient::__call #2): Changed !($nativeReflection->isPromoted() && ($nativeReflection->isReadOnly() || $nativeReflection->isHooked())) to (!$nativeReflection->isPromoted() || (!$nativeReflection->isReadOnly() && !$nativeReflection->isHooked())) in both src/Rules/IssetCheck.php and src/Analyser/MutatingScope.php. This is logically equivalent (De Morgan's law) but reads more clearly.

2. Added hooked property test case (reviewer feedback Nicer Markdown #1): Created tests/PHPStan/Rules/Variables/data/bug-14459-hooked.php with promoted hooked property test scenarios and added testBug14459Hooked() test method with #[RequiresPhp('>= 8.4')] in NullCoalesceRuleTest.php. The test verifies that a non-nullable promoted hooked property triggers the "not nullable" error, while a nullable one does not.

Both make tests and make phpstan pass cleanly.