POC: Use SimultaneousTypeTraverser in RuleLevelHelper::transformAcceptedType

src/Rules/RuleLevelHelper.php

@@ -6,6 +6,7 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\AutowiredParameter;
 use PHPStan\DependencyInjection\AutowiredService;
+use PHPStan\Reflection\ParametersAcceptor;
 use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\Type\BenevolentUnionType;
 use PHPStan\Type\CallableType;
@@ -16,6 +17,7 @@
 use PHPStan\Type\MixedType;
 use PHPStan\Type\NeverType;
 use PHPStan\Type\NullType;
+use PHPStan\Type\SimultaneousTypeTraverser;
 use PHPStan\Type\StrictMixedType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
@@ -87,20 +89,23 @@
 	private function transformAcceptedType(Type $acceptingType, Type $acceptedType): array
 	{
 		$checkForUnion = $this->checkUnionTypes;
-		$acceptedType = TypeTraverser::map($acceptedType, function (Type $acceptedType, callable $traverse) use ($acceptingType, &$checkForUnion): Type {
+		$acceptedType = SimultaneousTypeTraverser::map($acceptedType, $acceptingType, function (Type $acceptedType, Type $acceptingType, callable $traverse) use (&$checkForUnion): Type {
 			if ($acceptedType instanceof CallableType) {
 				if ($acceptedType->isCommonCallable()) {
 					return $acceptedType;
 				}
+				if (!$acceptingType instanceof ParametersAcceptor) {
+					return $acceptedType;
+				}
 
 				return new CallableType(
 					$acceptedType->getParameters(),
-					$traverse($this->transformCommonType($acceptedType->getReturnType())),
+					$traverse($this->transformCommonType($acceptedType->getReturnType()), $acceptingType->getReturnType()),
 					$acceptedType->isVariadic(),
 					$acceptedType->getTemplateTypeMap(),
 					$acceptedType->getResolvedTemplateTypeMap(),
 					$acceptedType->getTemplateTags(),
 					$acceptedType->isPure(),
 				);
 			}
 
@@ -109,9 +114,13 @@
 					return $acceptedType;
 				}
 
+				if (!$acceptingType instanceof ParametersAcceptor) {
+					return $acceptedType;
+				}
+
 				return new ClosureType(
 					$acceptedType->getParameters(),
-					$traverse($this->transformCommonType($acceptedType->getReturnType())),
+					$traverse($this->transformCommonType($acceptedType->getReturnType()), $acceptingType->getReturnType()),
 					$acceptedType->isVariadic(),
 					$acceptedType->getTemplateTypeMap(),
 					$acceptedType->getResolvedTemplateTypeMap(),
@@ -127,22 +136,23 @@
 
 			if (
 				!$this->checkNullables
-				&& !$acceptingType instanceof NullType
-				&& !$acceptedType instanceof NullType
 				&& !$acceptedType instanceof BenevolentUnionType
+				&& !$acceptedType instanceof NullType
+				&& TypeCombinator::containsNull($acceptedType)
+				&& !TypeCombinator::containsNull($acceptingType)
 			) {
-				return $traverse(TypeCombinator::removeNull($acceptedType));
+				return $traverse(TypeCombinator::removeNull($acceptedType), $acceptingType);
 			}
 
 			if ($this->checkBenevolentUnionTypes) {
 				if ($acceptedType instanceof BenevolentUnionType) {
 					$checkForUnion = true;
-					return $traverse(TypeUtils::toStrictUnion($acceptedType));
+					return $traverse(TypeUtils::toStrictUnion($acceptedType), $acceptingType);
 				}
 			}
 
-			return $traverse($this->transformCommonType($acceptedType));
+			return $traverse($this->transformCommonType($acceptedType), $acceptingType);
 		});
 
 		return [$acceptedType, $checkForUnion];
 	}

tests/PHPStan/Rules/Functions/ClosureReturnTypeRuleTest.php

@@ -13,9 +13,11 @@
 class ClosureReturnTypeRuleTest extends RuleTestCase
 {
 
+	private bool $checkNullables = true;
+
 	protected function getRule(): Rule
 	{
-		return new ClosureReturnTypeRule(new FunctionReturnTypeCheck(new RuleLevelHelper(self::createReflectionProvider(), true, false, true, false, false, false, true)));
+		return new ClosureReturnTypeRule(new FunctionReturnTypeCheck(new RuleLevelHelper(self::createReflectionProvider(), $this->checkNullables, false, true, false, false, false, true)));
 	}
 
 	public function testClosureReturnTypeRule(): void
@@ -128,6 +130,13 @@ public function testBug7220(): void
 		$this->analyse([__DIR__ . '/data/bug-7220.php'], []);
 	}
 
+	public function testBug12008(): void
+	{
+		$this->checkNullables = false;
+
+		$this->analyse([__DIR__ . '/data/bug-12008.php'], []);
+	}
+
 	public function testBugFunctionMethodConstants(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-anonymous-function-method-constant.php'], []);

tests/PHPStan/Rules/Functions/data/bug-12008.php

@@ -0,0 +1,42 @@
+<?php declare(strict_types = 1);
+
+namespace Bug12008;
+
+interface ProductOverview {
+	public function getId(): ?int;
+}
+
+/**
+ * @template T
+ */
+readonly class Pagination
+{
+	/**
+	 * @param iterable<T> $records
+	 */
+	public function __construct(
+		public iterable $records,
+	) {
+	}
+}
+
+class HelloWorld
+{
+	private function respondToApiRequest(Closure|null $data): never {
+		exit;
+	}
+
+	/**
+	 * @param list<ProductOverview> $products
+	 */
+	public function run(array $products): never {
+		$this->respondToApiRequest(function () use ($products) {
+			return new Pagination(array_map(
+				fn (ProductOverview $product) => [
+					'id' => $product->getId(),
+				],
+				$products,
+			));
+		});
+	}
+}