Stdlib: DOMDocument::getElementById() after loadHTML() — HTML id attribute not indexed (ext/dom/document.c) #15251

Category

stdlib · php-src-strict · ext/dom HTML lookup gap

Problem

After DOMDocument::loadHTML(), elements with an HTML id attribute are not found by getElementById(). Zend returns the matching element; VM returns null.

setIdAttribute() + XML DTD path works (#14493), but ordinary HTML id="..." from loadHTML() must also resolve without manual ID registration.

Verified 2026-07-03 on master.

php-src reference

• php/php-src ext/dom/document.c — HTML document id table
• php/php-src ext/dom/node.c — dom_element_set_id_attribute, libxml ID map

PHP implementation target

• ext/dom/VmDom.php — index id attributes during loadHTML() parse (or libxml HTML ID table bridge)
• Reuse existing manual ID map from DOMElement::setIdAttribute() where possible
• PHP-in-PHP + thin libxml bridge only

Repro (verified 2026-07-03)

./script/docker-exec.sh -- php bin/vm.php test/repro/maintainer_gap_dom_loadhtml_get_element_by_id.php
# fail: getElementById null (exit 1)
# Zend: ok

Repro: test/repro/maintainer_gap_dom_loadhtml_get_element_by_id.php

Related: closed #14378 (method exists), #14493 (setIdAttribute), #14356 (loadHTML).

Done when

• loadHTML('<p id="target">…</p>') then getElementById('target') returns element with correct textContent
• XML/DOM without HTML id still returns null when no ID map (existing compliance)
• Repro exits 0; compliance guard under test/compliance/cases/dom/ or stdlib/