Resolve template types of method calls on a concrete generic static return type

[pawell67]

A static<...> return type whose arguments reference no template type is not resolved on a generic receiver:

/**
 * @template TKey of array-key
 * @template TValue
 */
class Box
{
    /** @return static<int, string> */
    public function concrete() { return new static(); }

    /** @return static<int, TValue> */
    public function withTemplate() { return new static(); }

    /** @return array<TKey, TValue> */
    public function all(): array { return []; }
}

/** @param Box<string, bool> $box */
function test(Box $box): void {
    \PHPStan\dumpType($box->concrete()->all());     // array<TKey of (int|string), TValue>   (expected array<int, string>)
    \PHPStan\dumpType($box->withTemplate()->all()); // array<int, bool>
}

CalledOnTypeUnresolvedMethodPrototypeReflection::transformStaticType() turns the GenericStaticType into getStaticObjectType(), which hands the declaring class' ClassReflection (without the type arguments) to the GenericObjectType. When an argument contains a template, traverse() recreates the object and the reflection is resolved lazily, which is why only the fully concrete case breaks. I reproduced this on 2.2.14 and 2.3.0, so it is not a regression.

It is visible in Laravel's Collection (@return static<int, mixed> on flatten(), collapse(), values(), …): $collection->flatten()->merge($x) leaks TKey/TValue, which Larastan has to baseline in its monica E2E.

The fix builds the object without the stale reflection in transformStaticType() only. I first changed GenericStaticType::getStaticObjectType(), but that also changes new static(...) (NewHandler) and drops the expected error of ReturnTypeRuleTest::testBug4590, so I narrowed it to the method return type resolution.

Caveats:

• CalledOnTypeUnresolvedMethodPrototypeReflection is shadowed by turbo-ext. I have not ported the change to the .cpp mirror or run the suite with the extension loaded, since I can't build and verify it properly here. Happy to follow up if you prefer that in this PR.
• Full test suite (paratest, 22505 tests) passes without the extension.

🤖 Generated with Claude Code

[pawell67]

The last commit is a cherry-pick of #6697 (author kept): ResultCacheInfoCommandTest::testWarmAnalysisDoesNotRewriteUnchangedResultCache fails in the ubuntu "Integration tests" job regardless of this change, so it is included here only to get a green run. It drops out of the diff once #6697 is merged and this branch is rebased.

[pawell67]

Rebased on the current 2.3.x (the #6697 cherry-pick is gone, it landed upstream) and bumped the expected turbo version for the ported commit.

The last commit is a cherry-pick of #6729 (author kept): the result-cache-parse-error E2E step fails on 2.3.x since the BetterReflection update, independently of this change. It is here only to get a green run and drops out once #6729 is merged and this branch is rebased.

[pawell67]

@staabm would you mind taking a look? With phpstan/phpstan#15468 merged, CI here is fully green now. The fix is in CalledOnTypeUnresolvedMethodPrototypeReflection::transformStaticType() plus its turbo-ext mirror: a fully concrete static<int, string> return type kept the declaring class reflection, so calls on the result saw unresolved TKey/TValue. The last commit is the cherry-pick of #6729 and drops out once that is merged.