Add test cases for template property types to verify TypeCombinator::intersect() preserves generics

Adds test coverage for properties typed with class-level template parameters
(e.g. `@var \WeakMap<T, U>|null`) to ensure the intersect call in NewHandler
does not lose generic type information when template types are involved.

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

Author: phpstan-bot

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

@@ -67,3 +67,36 @@ public static function initStatic(): void
 		}
 	}
 }
+
+/**
+ * @template T of object
+ * @template U
+ */
+class Baz
+{
+	/**
+	 * @var \WeakMap<T, U>|null
+	 */
+	private ?\WeakMap $instanceMap = null;
+
+	/**
+	 * @var \WeakMap<T, U>|null
+	 */
+	private static ?\WeakMap $staticMap = null;
+
+	public function initInstance(): void
+	{
+		if ($this->instanceMap === null) {
+			$this->instanceMap = new \WeakMap();
+			assertType('WeakMap<T of object (class Bug11844Nsrt\Baz, argument), U (class Bug11844Nsrt\Baz, argument)>', $this->instanceMap);
+		}
+	}
+
+	public static function initStatic(): void
+	{
+		if (self::$staticMap === null) {
+			self::$staticMap = new \WeakMap();
+			assertType('WeakMap<T of object (class Bug11844Nsrt\Baz, argument), U (class Bug11844Nsrt\Baz, argument)>', self::$staticMap);
+		}
+	}
+}

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

@@ -104,3 +104,41 @@ public static function init(): void
 		}
 	}
 }
+
+/**
+ * @template T of object
+ * @template U
+ */
+class TemplatePropertyCase
+{
+	/**
+	 * @var \WeakMap<T, U>|null
+	 */
+	private ?\WeakMap $map = null;
+
+	public function init(): void
+	{
+		if ($this->map === null) {
+			$this->map = new \WeakMap();
+		}
+	}
+}
+
+/**
+ * @template T of object
+ * @template U
+ */
+class StaticTemplatePropertyCase
+{
+	/**
+	 * @var \WeakMap<T, U>|null
+	 */
+	private static ?\WeakMap $map = null;
+
+	public static function init(): void
+	{
+		if (self::$map === null) {
+			self::$map = new \WeakMap();
+		}
+	}
+}