Solve issue 9766

VincentLanglet · ondrejmirtes · commit 304d67eed6a6 · 2023-08-26T11:24:25.000+02:00
diff --git a/src/Rules/RuleLevelHelper.php b/src/Rules/RuleLevelHelper.php
@@ -19,6 +19,7 @@
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\TypeTraverser;
+use PHPStan\Type\TypeUtils;
 use PHPStan\Type\UnionType;
 use PHPStan\Type\VerbosityLevel;
 use function array_merge;
@@ -119,7 +120,7 @@ private function transformAcceptedType(Type $acceptingType, Type $acceptedType):
 			if ($this->checkBenevolentUnionTypes) {
 				if ($acceptedType instanceof BenevolentUnionType) {
 					$checkForUnion = true;
-					return $traverse(new UnionType($acceptedType->getTypes()));
+					return $traverse(TypeUtils::toStrictUnion($acceptedType));
 				}
 			}
 
@@ -149,7 +150,7 @@ public function acceptsWithReason(Type $acceptingType, Type $acceptedType, bool
 			$traverse = static function (Type $type, callable $traverse) use (&$checkForUnion): Type {
 				if ($type instanceof BenevolentUnionType) {
 					$checkForUnion = true;
-					return new UnionType($type->getTypes());
+					return TypeUtils::toStrictUnion($type);
 				}
 
 				return $traverse($type);
diff --git a/src/Type/TypeUtils.php b/src/Type/TypeUtils.php
@@ -8,7 +8,9 @@
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\Enum\EnumCaseObjectType;
+use PHPStan\Type\Generic\TemplateBenevolentUnionType;
 use PHPStan\Type\Generic\TemplateType;
+use PHPStan\Type\Generic\TemplateUnionType;
 use function array_merge;
 use function array_unique;
 use function array_values;
@@ -275,6 +277,28 @@ public static function toBenevolentUnion(Type $type): Type
 		return $type;
 	}
 
+	/**
+	 * @return ($type is UnionType ? UnionType : Type)
+	 */
+	public static function toStrictUnion(Type $type): Type
+	{
+		if ($type instanceof TemplateBenevolentUnionType) {
+			return new TemplateUnionType(
+				$type->getScope(),
+				$type->getStrategy(),
+				$type->getVariance(),
+				$type->getName(),
+				static::toStrictUnion($type->getBound()),
+			);
+		}
+
+		if ($type instanceof BenevolentUnionType) {
+			return new UnionType($type->getTypes());
+		}
+
+		return $type;
+	}
+
 	/**
 	 * @return Type[]
 	 */
diff --git a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
@@ -949,4 +949,10 @@ public function testBug6175(): void
 		$this->analyse([__DIR__ . '/data/bug-6175.php'], []);
 	}
 
+	public function testBug9766(): void
+	{
+		$this->checkBenevolentUnionTypes = true;
+		$this->analyse([__DIR__ . '/data/bug-9766.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Methods/data/bug-9766.php b/tests/PHPStan/Rules/Methods/data/bug-9766.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace Bug9766;
+
+/**
+ * @template TKey of array-key
+ * @template TItem
+ */
+abstract class PHPStanBug {
+	/**
+	 * @param iterable<TKey, TItem> $items
+	 */
+	public function __construct(
+		private iterable $items,
+	) {
+		// empty
+	}
+
+	/**
+	 * @return iterable<TKey, TItem>
+	 */
+	protected function getItems(): iterable {
+		return $this->items;
+	}
+}

Original file line number	Diff line number	Diff line change
`@@ -949,4 +949,10 @@ public function testBug6175(): void`
`949`	`949`	`$this->analyse([__DIR__ . '/data/bug-6175.php'], []);`
`950`	`950`	`}`
`951`	`951`
	`952`	`+ public function testBug9766(): void`
	`953`	`+ {`
	`954`	`+ $this->checkBenevolentUnionTypes = true;`
	`955`	`+ $this->analyse([__DIR__ . '/data/bug-9766.php'], []);`
	`956`	`+ }`
	`957`	`+`
`952`	`958`	`}`