Skip extension for non-native reflection classes instead of removing declaring class check entirely

The previous approach (removing the declaring class check entirely) caused the
extension to fire during self-analysis where BetterReflection adapters override
getAttributes(). This overrode BetterReflection's accurate return type with the
native ReflectionAttribute type, which lacks getArgumentsExpressions().

Instead of checking declaring class name === className (which fails for union
types because UnionTypeMethodReflection returns only the first member's declaring
class), check that the declaring class is a native PHP class (no namespace
separator). This correctly:
- Fires for user code (declaring class is native ReflectionClass etc.)
- Fires for union types (declaring class is first member's native class)
- Skips BetterReflection adapters during self-analysis (namespaced classes)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Reflection/ClassReflection.php

@@ -1570,7 +1570,7 @@ private function findAttributeFlags(): ?int
 
 			$attributeClass = $this->reflectionProvider->getClass(Attribute::class);
 			$arguments = [];
-			foreach ($nativeAttributes[0]->getArgumentsExpressions() as $i => $expression) { // @phpstan-ignore method.notFound (method exists on BetterReflection's ReflectionAttribute adapter)
+			foreach ($nativeAttributes[0]->getArgumentsExpressions() as $i => $expression) {
 				if ($i === '') {
 					throw new ShouldNotHappenException();
 				}

src/Type/Php/ReflectionGetAttributesMethodReturnTypeExtension.php

@@ -14,6 +14,7 @@
 use PHPStan\Type\Type;
 use ReflectionAttribute;
 use function count;
+use function str_contains;
 
 final class ReflectionGetAttributesMethodReturnTypeExtension implements DynamicMethodReturnTypeExtension
 {
@@ -32,7 +33,8 @@ public function getClass(): string
 
 	public function isMethodSupported(MethodReflection $methodReflection): bool
 	{
-		return $methodReflection->getName() === 'getAttributes';
+		return $methodReflection->getName() === 'getAttributes'
+			&& !str_contains($methodReflection->getDeclaringClass()->getName(), '\\');
 	}
 
 	public function getTypeFromMethodCall(MethodReflection $methodReflection, MethodCall $methodCall, Scope $scope): ?Type