Support for static return type

Author: ondrejmirtes

build/phpstan.neon

@@ -20,6 +20,7 @@ parameters:
 		- %rootDir%/tests/PHPStan/Generics/functions.php
 		- %rootDir%/tests/PHPStan/Reflection/UnionTypesTest.php
 		- %rootDir%/tests/PHPStan/Reflection/MixedTypeTest.php
+		- %rootDir%/tests/PHPStan/Reflection/StaticTypeTest.php
 		- ../tests/e2e/magic-setter/*
 	featureToggles:
 		readComposerPhpVersion: false

src/Analyser/MutatingScope.php

@@ -2667,6 +2667,11 @@ public function getFunctionType($type, bool $isNullable, bool $isVariadic): Type
 
 				return new NonexistentParentClassType();
 			}
+
+			if ($lowercasedClassName === 'static') {
+				return new StaticType($className);
+			}
+
 			return new ObjectType($className);
 		} elseif ($type instanceof Node\NullableType) {
 			return $this->getFunctionType($type->type, true, $isVariadic);

src/Type/TypehintHelper.php

@@ -45,6 +45,8 @@ private static function getTypeObjectFromTypehint(string $typeString, ?string $s
 					}
 				}
 				return new NonexistentParentClassType();
+			case 'static':
+				return $selfClass !== null ? new StaticType($selfClass) : new ErrorType();
 			default:
 				return new ObjectType($typeString);
 		}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -10009,6 +10009,15 @@ public function dataNativeMixedType(): array
 		return $this->gatherAssertTypes(__DIR__ . '/../Reflection/data/mixedType.php');
 	}
 
+	public function dataNativeStaticReturnType(): array
+	{
+		if (PHP_VERSION_ID < 80000 && !self::$useStaticReflectionProvider) {
+			return [];
+		}
+
+		return $this->gatherAssertTypes(__DIR__ . '/../Reflection/data/staticReturnType.php');
+	}
+
 	public function dataMinMaxReturnTypeWithArrays(): array
 	{
 		return $this->gatherAssertTypes(__DIR__ . '/data/minmax-arrays.php');
@@ -10076,6 +10085,7 @@ public function dataMinMaxReturnTypeWithArrays(): array
 	 * @dataProvider dataGraphicsDrawReturnTypes
 	 * @dataProvider dataNativeUnionTypes
 	 * @dataProvider dataMinMaxReturnTypeWithArrays
+	 * @dataProvider dataNativeStaticReturnType
 	 * @param string $assertType
 	 * @param string $file
 	 * @param mixed ...$args

tests/PHPStan/Reflection/StaticTypeTest.php

@@ -0,0 +1,28 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Reflection;
+
+use NativeStaticReturnType\Foo;
+use PHPStan\Testing\TestCase;
+use PHPStan\Type\StaticType;
+
+class StaticTypeTest extends TestCase
+{
+
+	public function testMixedType(): void
+	{
+		if (PHP_VERSION_ID < 80000 && !self::$useStaticReflectionProvider) {
+			$this->markTestSkipped('Test requires PHP 8.0');
+		}
+
+		$reflectionProvider = $this->createBroker();
+		$class = $reflectionProvider->getClass(Foo::class);
+
+		$method = $class->getNativeMethod('doFoo');
+		$methodVariant = ParametersAcceptorSelector::selectSingle($method->getVariants());
+		$methodReturnType = $methodVariant->getReturnType();
+		$this->assertInstanceOf(StaticType::class, $methodReturnType);
+		$this->assertSame(Foo::class, $methodReturnType->getClassName());
+	}
+
+}

tests/PHPStan/Reflection/data/staticReturnType.php

@@ -0,0 +1,55 @@
+<?php // lint >= 8.0
+
+namespace NativeStaticReturnType;
+
+use function PHPStan\Analyser\assertType;
+
+class Foo
+{
+
+	public function doFoo(): static
+	{
+		return new static();
+	}
+
+	public function doBar(): void
+	{
+		assertType('static(NativeStaticReturnType\Foo)', $this->doFoo());
+	}
+
+	/**
+	 * @return callable(): static
+	 */
+	public function doBaz(): callable
+	{
+		$f = function (): static {
+			return new static();
+		};
+
+		assertType('static(NativeStaticReturnType\Foo)', $f());
+
+		return $f;
+	}
+
+}
+
+class Bar extends Foo
+{
+
+}
+
+function (Foo $foo): void {
+	assertType('NativeStaticReturnType\Foo', $foo->doFoo());
+
+	$callable = $foo->doBaz();
+	assertType('callable(): NativeStaticReturnType\Foo', $callable);
+	assertType('NativeStaticReturnType\Foo', $callable());
+};
+
+function (Bar $bar): void {
+	assertType('NativeStaticReturnType\Bar', $bar->doFoo());
+
+	$callable = $bar->doBaz();
+	assertType('callable(): NativeStaticReturnType\Bar', $callable);
+	assertType('NativeStaticReturnType\Bar', $callable());
+};