Do not accept raw ObjectType in intersection as GenericObjectType<TemplateType>

Closes phpstan/phpstan#13190

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: rvanvelzen

phpstan-baseline.neon

@@ -1449,12 +1449,24 @@ parameters:
 			count: 1
 			path: src/Type/IntersectionType.php
 
+		-
+			rawMessage: Doing instanceof PHPStan\Type\Generic\GenericObjectType is error-prone and deprecated.
+			identifier: phpstanApi.instanceofType
+			count: 3
+			path: src/Type/IntersectionType.php
+
 		-
 			rawMessage: Doing instanceof PHPStan\Type\IntersectionType is error-prone and deprecated.
 			identifier: phpstanApi.instanceofType
 			count: 3
 			path: src/Type/IntersectionType.php
 
+		-
+			rawMessage: 'Doing instanceof PHPStan\Type\ObjectType is error-prone and deprecated. Use Type::isObject() or Type::getObjectClassNames() instead.'
+			identifier: phpstanApi.instanceofType
+			count: 1
+			path: src/Type/IntersectionType.php
+
 		-
 			rawMessage: 'Method PHPStan\Type\IntersectionType::getConstantArrays() should return list<PHPStan\Type\Constant\ConstantArrayType> but returns array{PHPStan\Type\Type}.'
 			identifier: return.type

src/Type/IntersectionType.php

@@ -44,6 +44,7 @@
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\Enum\EnumCaseObjectType;
+use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\Generic\TemplateArrayType;
 use PHPStan\Type\Generic\TemplateType;
 use PHPStan\Type\Generic\TemplateTypeMap;
@@ -339,6 +340,28 @@ public function isAcceptedBy(Type $acceptingType, bool $strictTypes): AcceptsRes
 			if ($isSuperType->no()) {
 				return $isSuperType->toAcceptsResult();
 			}
+			// A raw (non-generic) ObjectType in the intersection cannot satisfy a TemplateType
+			// argument — when isSuperTypeOf says Maybe, trust it over lazyMaxMin's Yes.
+			if ($isSuperType->maybe() && $acceptingType instanceof GenericObjectType) {
+				foreach ($acceptingType->getTypes() as $typeArg) {
+					if (!$typeArg instanceof TemplateType) {
+						continue;
+					}
+					foreach ($this->types as $innerType) {
+						if (
+							$innerType instanceof GenericObjectType
+							|| $innerType instanceof TemplateType
+							|| !$innerType instanceof ObjectType
+						) {
+							continue;
+						}
+						$ancestor = $innerType->getAncestorWithClassName($acceptingType->getClassName());
+						if ($ancestor !== null && !$ancestor instanceof GenericObjectType) {
+							return $isSuperType->toAcceptsResult();
+						}
+					}
+				}
+			}
 		}
 
 		if ($this->isOversizedArray()->yes()) {

tests/PHPStan/Rules/Functions/ReturnTypeRuleTest.php

@@ -455,7 +455,12 @@ public function testBug13190(): void
 	{
 		$this->checkNullables = true;
 		$this->checkExplicitMixed = false;
-		$this->analyse([__DIR__ . '/data/bug-13190.php'], []);
+		$this->analyse([__DIR__ . '/data/bug-13190.php'], [
+			[
+				'Function Bug13190\inbox() should return Bug13190\Box<T> but returns (Bug13190\Box&T)|Bug13190\Box<T>.',
+				51,
+			],
+		]);
 	}
 
 }