fix

Author: staabm

src/Type/MixedType.php

@@ -37,6 +37,7 @@
 use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\UndecidedComparisonCompoundTypeTrait;
+use function get_class;
 use function sprintf;
 
 /** @api */
@@ -310,11 +311,7 @@ public function getCallableParametersAcceptors(ClassMemberAccessAnswerer $scope)
 
 	public function equals(Type $type): bool
 	{
-		if (!$type instanceof self) {
-			return false;
-		}
-
-		if ($type instanceof ErrorType) {
+		if (get_class($type) !== static::class) {
 			return false;
 		}
 

tests/PHPStan/Generics/TemplateTypeFactoryTest.php

@@ -54,7 +54,12 @@ public function dataCreate(): array
 					null,
 					TemplateTypeVariance::createInvariant(),
 				),
-				new MixedType(),
+				TemplateTypeFactory::create(
+					TemplateTypeScope::createWithFunction('a'),
+					'U',
+					null,
+					TemplateTypeVariance::createInvariant(),
+				),
 			],
 			[
 				new UnionType([