support removing class-strings from GenericClassStringType

src/Type/Generic/GenericClassStringType.php

@@ -8,12 +8,14 @@
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\IntersectionType;
 use PHPStan\Type\MixedType;
+use PHPStan\Type\NeverType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\ObjectWithoutClassType;
 use PHPStan\Type\StaticType;
 use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\TypeWithClassName;
 use PHPStan\Type\UnionType;
 use PHPStan\Type\VerbosityLevel;
 use function sprintf;
@@ -172,4 +174,24 @@ public static function __set_state(array $properties): Type
 		return new self($properties['type']);
 	}
 
+	public function tryRemove(Type $typeToRemove): ?Type
+	{
+		if ($typeToRemove instanceof ConstantStringType && $typeToRemove->isClassString()) {
+			$generic = $this->getGenericType();
+
+			if ($generic instanceof TypeWithClassName) {
+				$classReflection = $generic->getClassReflection();
+				if (
+					$classReflection !== null
+					&& $classReflection->isFinal()
+					&& $generic->getClassName() === $typeToRemove->getValue()
+				) {
+					return new NeverType();
+				}
+			}
+		}
+
+		return parent::tryRemove($typeToRemove);
+	}
+
 }

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -962,6 +962,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Arrays/data/bug-5758.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Functions/data/bug-3931.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5223.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7698.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/bug-7698.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace Bug7698;
+
+declare(strict_types=1);
+
+use function PHPStan\Testing\assertType;
+
+final class A
+{
+}
+
+final class B
+{
+}
+
+final class Test
+{
+	public function __construct(public readonly A|B $value)
+	{
+	}
+}
+
+function foo()
+{
+	$t = new Test(new A());
+	$class = $t->value::class;
+	assertType('class-string<Bug7698\A>|class-string<Bug7698\B>', $class);
+
+	if ($class === A::class) {
+		return;
+	}
+
+	assertType('class-string<Bug7698\B>', $class);
+
+	if ($class === B::class) {
+		return;
+	}
+
+	assertType('*NEVER*', $class);
+}

tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php

@@ -224,4 +224,13 @@ public function testBug7622(): void
 		$this->analyse([__DIR__ . '/data/bug-7622.php'], []);
 	}
 
+	public function testBug7698(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			$this->markTestSkipped('Test requires PHP 8.1.');
+		}
+		$this->treatPhpDocTypesAsCertain = false;
+		$this->analyse([__DIR__ . '/data/bug-7698.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Comparison/data/bug-7698.php

@@ -0,0 +1,51 @@
+<?php // lint >= 8.1
+
+namespace Bug7698Match;
+
+final class A
+{
+}
+
+final class B
+{
+}
+
+final class C
+{
+}
+
+final class Test
+{
+	public function __construct(public readonly A|B $value)
+	{
+	}
+}
+
+function matchIt()
+{
+	$t = new Test(new A());
+	$class = $t->value::class;
+	echo match ($class) {
+		A::class => 'A',
+		B::class => 'B'
+	};
+}
+
+function matchGetClassString()
+{
+	$t = new Test(new A());
+	echo match (get_class($t->value)) {
+		A::class => 'A',
+		B::class => 'B'
+	};
+}
+
+function test(A|B|C $abc): string
+{
+	$class = $abc::class;
+	return match ($class) {
+		A::class => 'A',
+		B::class => 'B',
+		C::class => 'C',
+	};
+}