Support null templates

Author: SplotyCode

src/Rules/Generics/TemplateTypeCheck.php

@@ -28,6 +28,7 @@
 use PHPStan\Type\IterableType;
 use PHPStan\Type\KeyOfType;
 use PHPStan\Type\MixedType;
+use PHPStan\Type\NullType;
 use PHPStan\Type\ObjectShapeType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\ObjectWithoutClassType;
@@ -132,6 +133,7 @@ public function check(
 				&& $boundTypeClass !== GenericObjectType::class
 				&& $boundTypeClass !== KeyOfType::class
 				&& $boundTypeClass !== IterableType::class
+				&& $boundTypeClass !== NullType::class
 				&& !$boundType instanceof UnionType
 				&& !$boundType instanceof IntersectionType
 				&& !$boundType instanceof TemplateType

tests/PHPStan/Analyser/nsrt/template-null-bound.php

@@ -17,10 +17,20 @@ public function doFoo(?int $p): ?int
 		return $p;
 	}
 
+	/**
+	 * @template T of null
+	 * @return T
+	 */
+	public function nullTemplate(): mixed
+	{
+		return null;
+	}
+
 }
 
 function (Foo $f, ?int $i): void {
 	assertType('null', $f->doFoo(null));
 	assertType('1', $f->doFoo(1));
 	assertType('int|null', $f->doFoo($i));
+	assertType('null', $f->nullTemplate());
 };