Use TypeCombinator::intersect() to extract matching type from property union

When the property type is a union like `WeakMap<object,string>|null|false`,
`TypeCombinator::removeNull()` only strips `null`, leaving `WeakMap<object,string>|false`.
The subsequent `isSuperTypeOf()` check then fails because `false` is not a subtype of `WeakMap`.

Using `TypeCombinator::intersect()` with the class type properly extracts only
the matching part of the union (e.g. `WeakMap<object,string>`), handling any
combination of non-object types in the property's declared type.

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

Author: phpstan-bot

src/Analyser/ExprHandler/NewHandler.php

@@ -420,9 +420,9 @@ private function exactInstantiation(MutatingScope $scope, New_ $node, Name $clas
 				if (count($classTemplateTypes) === count($originalClassTemplateTypes)) {
 					$foundProperty = $this->propertyReflectionFinder->findPropertyReflectionFromNode($assignedToProperty, $scope);
 					if ($foundProperty !== null) {
-						$propertyType = TypeCombinator::removeNull($foundProperty->getWritableType());
 						$nonFinalObjectType = $isStatic ? new StaticType($nonFinalClassReflection) : new ObjectType($resolvedClassName, classReflection: $nonFinalClassReflection);
-						if ($nonFinalObjectType->isSuperTypeOf($propertyType)->yes()) {
+						$propertyType = TypeCombinator::intersect($foundProperty->getWritableType(), $nonFinalObjectType);
+						if (!($propertyType instanceof NeverType) && $nonFinalObjectType->isSuperTypeOf($propertyType)->yes()) {
 							return $propertyType;
 						}
 					}

tests/PHPStan/Analyser/nsrt/bug-11844.php

@@ -34,3 +34,36 @@ public function initInstance(): void
 		}
 	}
 }
+
+class Bar
+{
+	/**
+	 * @var \WeakMap<object, string>|null|false
+	 */
+	private \WeakMap|null|false $instanceMap = false;
+
+	/**
+	 * @var \WeakMap<object, string>|null|false
+	 */
+	private static \WeakMap|null|false $staticMap = false;
+
+	public function initInstance(): void
+	{
+		if ($this->instanceMap !== false) {
+			if ($this->instanceMap === null) {
+				$this->instanceMap = new \WeakMap();
+				assertType('WeakMap<object, string>', $this->instanceMap);
+			}
+		}
+	}
+
+	public static function initStatic(): void
+	{
+		if (self::$staticMap !== false) {
+			if (self::$staticMap === null) {
+				self::$staticMap = new \WeakMap();
+				assertType('WeakMap<object, string>', self::$staticMap);
+			}
+		}
+	}
+}

tests/PHPStan/Rules/TooWideTypehints/data/bug-11844.php

@@ -46,6 +46,50 @@ public function __construct($value) {
 	}
 }
 
+class NullOrFalsePropertyCase
+{
+	/**
+	 * @var \WeakMap<object, string>|null|false
+	 */
+	private \WeakMap|null|false $map = false;
+
+	public function init(): void
+	{
+		if ($this->map !== false) {
+			if ($this->map === null) {
+				$this->map = new \WeakMap();
+			}
+		}
+	}
+
+	public function reset(): void
+	{
+		$this->map = null;
+	}
+}
+
+class StaticNullOrFalsePropertyCase
+{
+	/**
+	 * @var \WeakMap<object, string>|null|false
+	 */
+	private static \WeakMap|null|false $map = false;
+
+	public static function init(): void
+	{
+		if (self::$map !== false) {
+			if (self::$map === null) {
+				self::$map = new \WeakMap();
+			}
+		}
+	}
+
+	public static function reset(): void
+	{
+		self::$map = null;
+	}
+}
+
 class OtherGenericCase
 {
 	/**