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/AnalyserIntegrationTest.php

@@ -1496,7 +1496,7 @@ public function testBug12979(): void
 
 	public function testBug12095(): void
 	{
-		$errors = $this->runAnalyse(__DIR__ . '/data/bug-12095.php');
+		$errors = $this->runAnalyse(__DIR__ . '/nsrt/bug-12894.php');
 		$this->assertNoErrors($errors);
 	}
 

tests/PHPStan/Analyser/nsrt/bug-12894.php

@@ -2,17 +2,24 @@
 
 namespace Bug12894;
 
+use Closure;
+
 /**
  * @template TValue of object|null
  */
-interface Dependency {
+interface Dependency
+{
+
 	/**
 	 * @return TValue
 	 */
 	public function __invoke(): object|null;
+
 }
 
-interface DependencyResolver {
+interface DependencyResolver
+{
+
 	/**
 	 * @template V of object|null
 	 * @template D of Dependency<V>
@@ -22,12 +29,12 @@ interface DependencyResolver {
 	 * @return V
 	 */
 	public function resolve(Dependency $dependency): object|null;
+
 }
 
-/**
- * @internal
- */
-class Resolver implements DependencyResolver {
+class Resolver implements DependencyResolver
+{
+
 	public function __construct(
 		/**
 		 * @var Closure(object|null): void
@@ -39,8 +46,11 @@ public function __construct(
 
 	public function resolve(Dependency $dependency): object|null {
 		$resolved = $dependency();
+		\PHPStan\Testing\assertType('V of object|null (method Bug12894\DependencyResolver::resolve(), argument)', $resolved);
 		$result = is_object($resolved) ? 1 : 2;
+		\PHPStan\Testing\assertType('V of object (method Bug12894\DependencyResolver::resolve(), argument)|V of null (method Bug12894\DependencyResolver::resolve(), argument)', $resolved);
 		($this->run)($resolved);
 		return $resolved;
 	}
+
 }

tests/PHPStan/Analyser/nsrt/bug-12989.php

@@ -10,8 +10,8 @@
 function a(?int $b): ?int
 {
 	if ($b === null) {
+		\PHPStan\Testing\assertType('null', $b);
 		return $b;
 	}
 	return $b;
 }
-

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());
 };

tests/PHPStan/Rules/Generics/FunctionTemplateTypeRuleTest.php

@@ -56,10 +56,6 @@ public function testRule(): void
 				'PHPDoc tag @template T for function FunctionTemplateType\resourceBound() with bound type resource is not supported.',
 				50,
 			],
-			[
-				'PHPDoc tag @template T for function FunctionTemplateType\nullNotSupported() with bound type null is not supported.',
-				68,
-			],
 			[
 				'Call-site variance of covariant int in generic type FunctionTemplateType\GenericCovariant<covariant int> in PHPDoc tag @template U is redundant, template type T of class FunctionTemplateType\GenericCovariant has the same variance.',
 				94,

tests/PHPStan/Rules/Generics/data/function-template.php

@@ -65,7 +65,7 @@ function nakano()
 }
 
 /** @template T of null */
-function nullNotSupported()
+function nullSupported()
 {
 
 }

tests/PHPStan/Rules/PhpDoc/IncompatiblePropertyPhpDocTypeRuleTest.php

@@ -186,10 +186,6 @@ public function testGenericCallables(): void
 				'PHPDoc tag @var template of callable<TypeAlias of mixed>(TypeAlias): TypeAlias cannot have existing type alias TypeAlias as its name.',
 				26,
 			],
-			[
-				'PHPDoc tag @var template TNull of callable<TNull of null>(TNull): TNull with bound type null is not supported.',
-				31,
-			],
 			[
 				'PHPDoc tag @var template TInvalid of callable<TInvalid of GenericCallableProperties\Invalid>(TInvalid): TInvalid has invalid bound type GenericCallableProperties\Invalid.',
 				36,