From 006759e0b3a34a33e9c9320367ac85aae40ab9bf Mon Sep 17 00:00:00 2001
From: PurHur <PurHur@users.noreply.github.com>
Date: Sat, 11 Jul 2026 05:02:27 +0000
Subject: [PATCH] ext/dom: initialize DOMElement::tagName slot on createElement
 (#3326)

Register tagName on DOMElement and populate it alongside nodeName so JIT/AOT
property-slot reads match VM DomNodePropertySupport parity.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 ext/dom/VmDom.php                                      |  7 +++++++
 test/compliance/DomDocumentVMTest.php                  |  4 ++++
 test/compliance/cases/stdlib/dom_element_tag_name.phpt | 10 ++++++++++
 test/repro/maintainer_gap_dom_element_tag_name_jit.php |  7 +++++++
 4 files changed, 28 insertions(+)
 create mode 100644 test/compliance/cases/stdlib/dom_element_tag_name.phpt
 create mode 100644 test/repro/maintainer_gap_dom_element_tag_name_jit.php

diff --git a/ext/dom/VmDom.php b/ext/dom/VmDom.php
index e8bb2126051..895ef58d425 100644
--- a/ext/dom/VmDom.php
+++ b/ext/dom/VmDom.php
@@ -570,6 +570,7 @@ public static function registerClasses(Context $ctx): void
         $element->isInternal = true;
         $element->parentLc = self::CLASS_NODE;
         $element->properties[] = new ClassProperty(self::PROP_NODE_NAME, null, $strProto);
+        $element->properties[] = new ClassProperty(self::PROP_TAG_NAME, null, $strProto);
         $element->properties[] = new ClassProperty(self::PROP_ATTRIBUTES, $nullProto, $objProto);
         $element->methods['appendchild'] = new ElementAppendChild();
         $element->methodVisibility['appendchild'] = $pub;
@@ -857,6 +858,9 @@ public static function createElement(
         $entry = new ObjectEntry($class);
         $entry->constructed = true;
         $entry->getProperty(self::PROP_NODE_NAME)->string($name);
+        if ($entry->hasProperty(self::PROP_TAG_NAME)) {
+            $entry->getProperty(self::PROP_TAG_NAME)->string($name);
+        }
         self::initElementPropertySlots($entry);
 
         $state = new DomNodeState();
@@ -896,6 +900,9 @@ public static function createElementNS(
         $entry = new ObjectEntry($class);
         $entry->constructed = true;
         $entry->getProperty(self::PROP_NODE_NAME)->string($qualifiedName);
+        if ($entry->hasProperty(self::PROP_TAG_NAME)) {
+            $entry->getProperty(self::PROP_TAG_NAME)->string($qualifiedName);
+        }
         self::initElementPropertySlots($entry);
 
         $state = new DomNodeState();
diff --git a/test/compliance/DomDocumentVMTest.php b/test/compliance/DomDocumentVMTest.php
index 35f100dc42b..9d4054562f3 100644
--- a/test/compliance/DomDocumentVMTest.php
+++ b/test/compliance/DomDocumentVMTest.php
@@ -45,6 +45,10 @@ public static function providePHPTests(): \Generator
             __DIR__.'/cases/stdlib/dom_create_element_ns.phpt',
             'dom_create_element_ns.phpt'
         );
+        yield 'dom_element_tag_name.phpt' => self::parsePHPT(
+            __DIR__.'/cases/stdlib/dom_element_tag_name.phpt',
+            'dom_element_tag_name.phpt'
+        );
         yield 'dom_namespace_attributes.phpt' => self::parsePHPT(
             __DIR__.'/cases/stdlib/dom_namespace_attributes.phpt',
             'dom_namespace_attributes.phpt'
diff --git a/test/compliance/cases/stdlib/dom_element_tag_name.phpt b/test/compliance/cases/stdlib/dom_element_tag_name.phpt
new file mode 100644
index 00000000000..30144d4ebe3
--- /dev/null
+++ b/test/compliance/cases/stdlib/dom_element_tag_name.phpt
@@ -0,0 +1,10 @@
+--TEST--
+DOMElement::tagName readable after createElement (ext/dom/node.c, #3326)
+--FILE--
+<?php
+declare(strict_types=1);
+$doc = new DOMDocument();
+$el = $doc->createElement('item');
+echo $el->tagName, "\n";
+--EXPECT--
+item
diff --git a/test/repro/maintainer_gap_dom_element_tag_name_jit.php b/test/repro/maintainer_gap_dom_element_tag_name_jit.php
new file mode 100644
index 00000000000..2ce9a1ab9be
--- /dev/null
+++ b/test/repro/maintainer_gap_dom_element_tag_name_jit.php
@@ -0,0 +1,7 @@
+<?php
+
+declare(strict_types=1);
+
+$doc = new DOMDocument();
+$el = $doc->createElement('p');
+echo $el->nodeName, ':', $el->tagName;