fix(type-system): sealed class-string match exhaustiveness for ::class comparisons

GenericClassStringType::tryRemove() did not handle @phpstan-sealed hierarchies,
so match expressions on $foo::class falsely reported unhandled remaining values
even when all allowed subtypes were covered. Delegates to TypeCombinator::remove()
which already handles sealed subtraction via ObjectType::changeSubtractedType().

Closes phpstan/phpstan#12241

Co-Authored-By: Ondrej Mirtes <ondrej@mirtes.cz>

Author: mhert

src/Type/Generic/GenericClassStringType.php

@@ -219,6 +219,18 @@ public function tryRemove(Type $typeToRemove): ?Type
 					if ($classReflection->isFinal() && $genericObjectClassNames[0] === $typeToRemove->getValue()) {
 						return new NeverType();
 					}
+
+					if ($classReflection->getAllowedSubTypes() !== null) {
+						$objectTypeToRemove = new ObjectType($typeToRemove->getValue());
+						$remainingType = TypeCombinator::remove($generic, $objectTypeToRemove);
+						if ($remainingType instanceof NeverType) {
+							return new NeverType();
+						}
+
+						if (!$remainingType->equals($generic)) {
+							return new self($remainingType);
+						}
+					}
 				}
 			} elseif (count($genericObjectClassNames) > 1) {
 				$objectTypeToRemove = new ObjectType($typeToRemove->getValue());

tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php

@@ -447,6 +447,12 @@ public function testBug9534(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.0')]
+	public function testBug12241(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-12241.php'], []);
+	}
+
 	#[RequiresPhp('>= 8.0')]
 	public function testBug13029(): void
 	{

tests/PHPStan/Rules/Comparison/data/bug-12241.php

@@ -0,0 +1,20 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug12241;
+
+/**
+ * @phpstan-sealed Bar|Baz
+ */
+abstract class Foo{}
+
+final class Bar extends Foo{}
+final class Baz extends Foo{}
+
+function (Foo $foo): string {
+	return match ($foo::class) {
+		Bar::class => 'Bar',
+		Baz::class => 'Baz',
+	};
+};