Inferring new from parent constructor - reject types that would fail bound check of the child class

Author: ondrejmirtes

src/Analyser/MutatingScope.php

@@ -5575,7 +5575,7 @@ private function exactInstantiation(New_ $node, string $className): ?Type
 					continue;
 				}
 
-				$ancestorMapping[$typeName] = $templateType->getName();
+				$ancestorMapping[$typeName] = $templateType;
 			}
 
 			$resolvedTypeMap = [];
@@ -5584,12 +5584,17 @@ private function exactInstantiation(New_ $node, string $className): ?Type
 					continue;
 				}
 
-				if (!array_key_exists($ancestorMapping[$typeName], $resolvedTypeMap)) {
-					$resolvedTypeMap[$ancestorMapping[$typeName]] = $type;
+				$ancestorType = $ancestorMapping[$typeName];
+				if (!$ancestorType->getBound()->isSuperTypeOf($type)->yes()) {
 					continue;
 				}
 
-				$resolvedTypeMap[$ancestorMapping[$typeName]] = TypeCombinator::union($resolvedTypeMap[$ancestorMapping[$typeName]], $type);
+				if (!array_key_exists($ancestorType->getName(), $resolvedTypeMap)) {
+					$resolvedTypeMap[$ancestorType->getName()] = $type;
+					continue;
+				}
+
+				$resolvedTypeMap[$ancestorType->getName()] = TypeCombinator::union($resolvedTypeMap[$ancestorType->getName()], $type);
 			}
 
 			return new GenericObjectType(

tests/PHPStan/Analyser/nsrt/bug-12386.php

@@ -0,0 +1,68 @@
+<?php
+
+namespace Bug12386;
+
+use function PHPStan\Testing\assertType;
+
+function doFoo() {
+	$landMapper = new Application_Model_Mapper_Land();
+	assertType('Bug12386\\Clx_Model_Iterator<Bug12386\\Application_Model_Land>', $landMapper->fetchAllActivePrependDefault(12));
+}
+
+/**
+ * @template T of Clx_Model_Abstract
+ */
+abstract class Clx_Model_Mapper_Abstract
+{
+	public function __construct()
+	{
+	}
+}
+
+/**
+ * @template T of Application_Model_Land
+ *
+ * @extends  Clx_Model_Mapper_Abstract<T>
+ */
+class ClxProductNet_Model_Mapper_Land extends Clx_Model_Mapper_Abstract
+{
+	/**
+	 * @param int $defaultLandid
+	 *
+	 * @return Clx_Model_Iterator<T>
+	 */
+	public function fetchAllActivePrependDefault($defaultLandid): Clx_Model_Iterator
+	{}
+}
+
+/**
+ * @template T of Application_Model_Land
+ *
+ * @extends  ClxProductNet_Model_Mapper_Land<T>
+ */
+final class Application_Model_Mapper_Land extends ClxProductNet_Model_Mapper_Land
+{
+}
+
+/**
+ * @template T of Clx_Model_Abstract
+ *
+ * @implements \Iterator<T>
+ */
+abstract class Clx_Model_Iterator implements \Countable, \Iterator
+{}
+
+abstract class Clx_Model_Abstract implements \Stringable
+{}
+
+abstract class ClxProductNet_Model_Land extends Clx_Model_Abstract
+{}
+
+final class Application_Model_Land extends ClxProductNet_Model_Land
+{
+	public function __toString()
+	{
+		return 'foo';
+	}
+
+}