Mark DOMXPath as uncloneable

This never resulted in a working XPath object anyway, as trying to query
or evaluate anything resulted in an "Invalid XPath context" error.
Supporting this is more trouble than it's worth, so just block the clone
operation.

Author: nielsdos

UPGRADING

@@ -41,6 +41,9 @@ PHP 8.4 UPGRADE NOTES
     DOMException now. This situation is extremely unlikely though and probably
     will not affect you. As a result DOMImplementation::createDocument() now has
     a tentative return type of DOMDocument instead of DOMDocument|false.
+  . Previously, DOMXPath objects could be cloned, but resulted in an unusable
+    object. This is no longer possible, and cloning a DOMXPath object now throws
+    an error.
 
 - MBString:
   . mb_encode_numericentity() and mb_decode_numericentity() now check that

ext/dom/php_dom.c

@@ -872,6 +872,7 @@ PHP_MINIT_FUNCTION(dom)
 	dom_xpath_object_handlers.offset = XtOffsetOf(dom_xpath_object, dom) + XtOffsetOf(dom_object, std);
 	dom_xpath_object_handlers.free_obj = dom_xpath_objects_free_storage;
 	dom_xpath_object_handlers.get_gc = dom_xpath_get_gc;
+	dom_xpath_object_handlers.clone_obj = NULL;
 
 	dom_xpath_class_entry = register_class_DOMXPath();
 	dom_xpath_class_entry->create_object = dom_xpath_objects_new;

ext/dom/tests/DOMXPath_clone.phpt

@@ -0,0 +1,22 @@
+--TEST--
+DOMXPath: Cloning a DOMXPath object
+--EXTENSIONS--
+dom
+--SKIPIF--
+<?php
+if (!class_exists('DOMXPath')) die('skip no xpath support');
+?>
+--FILE--
+<?php
+
+$dom = new DOMDocument;
+$xpath = new DOMXPath($dom);
+try {
+    clone $xpath;
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Trying to clone an uncloneable object of class DOMXPath