Fix phpstan/phpstan#4860: Error „should return static(Test) but returns Test“

[phpstan-bot]

Summary

get_class($this) was returning class-string<ClassName> instead of class-string<static(ClassName)>, causing false positive errors when the result was passed to a template method that should preserve the static type. For example, a copy(): static method calling $this->copyTo(get_class($this)) where copyTo has @template T and @param class-string<T> / @return T would incorrectly report "should return static(Test) but returns Test".

Changes

• Modified StaticType::getClassStringType() in src/Type/StaticType.php to return new GenericClassStringType($this) instead of delegating to getStaticObjectType()->getClassStringType(), which was losing the static type information
• Updated test expectations in tests/PHPStan/Analyser/data/bug-7391b.php, tests/PHPStan/Analyser/nsrt/get-parent-class.php, and tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php to reflect the more precise type descriptions

Root cause

StaticType::getClassStringType() was delegating to getStaticObjectType() which resolves the StaticType to a plain ObjectType, losing the static/$this information. This meant get_class($this) returned class-string<Foo> instead of class-string<$this(Foo)>. When this was passed to a template method with @param class-string<T> @return T, the template T resolved to Foo instead of static(Foo), causing the false positive.

Test

Added tests/PHPStan/Analyser/nsrt/bug-4860.php which verifies that get_class($this) returns class-string<$this(ClassName)> and that passing it to a template method correctly preserves the static type.

Fixes phpstan/phpstan#4860