From f35453b7efe8128f7672620c2581d81472ee41f0 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 13 Dec 2023 17:37:42 +0100
Subject: [PATCH 01/18] Add throw on every special element

---
 .../html-api/class-wp-html-processor.php      | 179 ++++++++++++++++++
 1 file changed, 179 insertions(+)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index e46c368c702d4..3d285ade80713 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -603,6 +603,185 @@ private function step_in_body() {
 		$op       = "{$op_sigil}{$tag_name}";
 
 		switch ( $op ) {
+			/*
+			 * These tags require special handling in the 'in body' insertion mode
+			 * but do not have special handling implemented yet.
+			 *
+			 * We throw the WP_HTML_Unsupported_Exception so we're free to implememnt
+			 * the catch-all handling for any other start and end tag.
+			 *
+			 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inbody
+			 */
+			case '+A':
+			case '+ADDRESS':
+			case '+APPLET':
+			case '+AREA':
+			case '+ARTICLE':
+			case '+ASIDE':
+			case '+B':
+			case '+BASE':
+			case '+BASEFONT':
+			case '+BGSOUND':
+			case '+BIG':
+			case '+BLOCKQUOTE':
+			case '+BODY':
+			case '+BR':
+			case '+BUTTON':
+			case '+CAPTION':
+			case '+CENTER':
+			case '+CODE':
+			case '+COL':
+			case '+COLGROUP':
+			case '+DD':
+			case '+DETAILS':
+			case '+DIALOG':
+			case '+DIR':
+			case '+DIV':
+			case '+DL':
+			case '+DT':
+			case '+EM':
+			case '+EMBED':
+			case '+FIELDSET':
+			case '+FIGCAPTION':
+			case '+FIGURE':
+			case '+FONT':
+			case '+FOOTER':
+			case '+FORM':
+			case '+FRAME':
+			case '+FRAMESET':
+			case '+H1':
+			case '+H2':
+			case '+H3':
+			case '+H4':
+			case '+H5':
+			case '+H6':
+			case '+HEAD':
+			case '+HEADER':
+			case '+HGROUP':
+			case '+HR':
+			case '+HTML':
+			case '+I':
+			case '+IFRAME':
+			case '+IMAGE':
+			case '+IMG':
+			case '+INPUT':
+			case '+KEYGEN':
+			case '+LI':
+			case '+LINK':
+			case '+LISTING':
+			case '+MAIN':
+			case '+MARQUEE':
+			case '+MATH':
+			case '+MENU':
+			case '+META':
+			case '+NAV':
+			case '+NOBR':
+			case '+NOEMBED':
+			case '+NOFRAMES':
+			case '+NOSCRIPT': // scripting flag??
+			case '+OBJECT':
+			case '+OL':
+			case '+OPTGROUP':
+			case '+OPTION':
+			case '+P':
+			case '+PARAM':
+			case '+PLAINTEXT':
+			case '+PRE':
+			case '+RB':
+			case '+RP':
+			case '+RT':
+			case '+RTC':
+			case '+S':
+			case '+SCRIPT':
+			case '+SEARCH':
+			case '+SECTION':
+			case '+SELECT':
+			case '+SMALL':
+			case '+SOURCE':
+			case '+STRIKE':
+			case '+STRONG':
+			case '+STYLE':
+			case '+SUMMARY':
+			case '+SVG':
+			case '+TABLE':
+			case '+TBODY':
+			case '+TD':
+			case '+TEMPLATE':
+			case '+TEXTAREA':
+			case '+TFOOT':
+			case '+TH':
+			case '+THEAD':
+			case '+TITLE':
+			case '+TR':
+			case '+TRACK':
+			case '+TT':
+			case '+U':
+			case '+UL':
+			case '+WBR':
+			case '+XMP':
+			case '-A':
+			case '-ADDRESS':
+			case '-APPLET':
+			case '-ARTICLE':
+			case '-ASIDE':
+			case '-B':
+			case '-BIG':
+			case '-BLOCKQUOTE':
+			case '-BODY':
+			case '-BR':
+			case '-BUTTON':
+			case '-CENTER':
+			case '-CODE':
+			case '-DD':
+			case '-DETAILS':
+			case '-DIALOG':
+			case '-DIR':
+			case '-DIV':
+			case '-DL':
+			case '-DT':
+			case '-EM':
+			case '-FIELDSET':
+			case '-FIGCAPTION':
+			case '-FIGURE':
+			case '-FONT':
+			case '-FOOTER':
+			case '-FORM':
+			case '-H1':
+			case '-H2':
+			case '-H3':
+			case '-H4':
+			case '-H5':
+			case '-H6':
+			case '-HEADER':
+			case '-HGROUP':
+			case '-HTML':
+			case '-I':
+			case '-LI':
+			case '-LISTING':
+			case '-MAIN':
+			case '-MARQUEE':
+			case '-MENU':
+			case '-NAV':
+			case '-NOBR':
+			case '-OBJECT':
+			case '-OL':
+			case '-P':
+			case '-PRE':
+			case '-S':
+			case '-SEARCH':
+			case '-SECTION':
+			case '-SMALL':
+			case '-STRIKE':
+			case '-STRONG':
+			case '-SUMMARY':
+			case '-TEMPLATE':
+			case '-TT':
+			case '-U':
+			case '-UL':
+				$this->last_error = self::ERROR_UNSUPPORTED;
+				throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
+
+
 			/*
 			 * > A start tag whose tag name is "button"
 			 */

From dbf5db80685a3c680a3d32e0e7fe268688c29c83 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 13 Dec 2023 17:57:56 +0100
Subject: [PATCH 02/18] Remove handled tags

---
 .../html-api/class-wp-html-processor.php      | 73 -------------------
 1 file changed, 73 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 3d285ade80713..f7f874e86f69c 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -612,40 +612,20 @@ private function step_in_body() {
 			 *
 			 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inbody
 			 */
-			case '+A':
-			case '+ADDRESS':
 			case '+APPLET':
 			case '+AREA':
-			case '+ARTICLE':
-			case '+ASIDE':
-			case '+B':
 			case '+BASE':
 			case '+BASEFONT':
 			case '+BGSOUND':
-			case '+BIG':
 			case '+BLOCKQUOTE':
 			case '+BODY':
 			case '+BR':
-			case '+BUTTON':
 			case '+CAPTION':
-			case '+CENTER':
-			case '+CODE':
 			case '+COL':
 			case '+COLGROUP':
 			case '+DD':
-			case '+DETAILS':
-			case '+DIALOG':
-			case '+DIR':
-			case '+DIV':
-			case '+DL':
 			case '+DT':
-			case '+EM':
 			case '+EMBED':
-			case '+FIELDSET':
-			case '+FIGCAPTION':
-			case '+FIGURE':
-			case '+FONT':
-			case '+FOOTER':
 			case '+FORM':
 			case '+FRAME':
 			case '+FRAMESET':
@@ -656,25 +636,18 @@ private function step_in_body() {
 			case '+H5':
 			case '+H6':
 			case '+HEAD':
-			case '+HEADER':
-			case '+HGROUP':
 			case '+HR':
 			case '+HTML':
-			case '+I':
 			case '+IFRAME':
 			case '+IMAGE':
-			case '+IMG':
 			case '+INPUT':
 			case '+KEYGEN':
 			case '+LI':
 			case '+LINK':
 			case '+LISTING':
-			case '+MAIN':
 			case '+MARQUEE':
 			case '+MATH':
-			case '+MENU':
 			case '+META':
-			case '+NAV':
 			case '+NOBR':
 			case '+NOEMBED':
 			case '+NOFRAMES':
@@ -683,7 +656,6 @@ private function step_in_body() {
 			case '+OL':
 			case '+OPTGROUP':
 			case '+OPTION':
-			case '+P':
 			case '+PARAM':
 			case '+PLAINTEXT':
 			case '+PRE':
@@ -691,17 +663,10 @@ private function step_in_body() {
 			case '+RP':
 			case '+RT':
 			case '+RTC':
-			case '+S':
 			case '+SCRIPT':
-			case '+SEARCH':
-			case '+SECTION':
 			case '+SELECT':
-			case '+SMALL':
 			case '+SOURCE':
-			case '+STRIKE':
-			case '+STRONG':
 			case '+STYLE':
-			case '+SUMMARY':
 			case '+SVG':
 			case '+TABLE':
 			case '+TBODY':
@@ -714,37 +679,15 @@ private function step_in_body() {
 			case '+TITLE':
 			case '+TR':
 			case '+TRACK':
-			case '+TT':
-			case '+U':
 			case '+UL':
 			case '+WBR':
 			case '+XMP':
-			case '-A':
-			case '-ADDRESS':
 			case '-APPLET':
-			case '-ARTICLE':
-			case '-ASIDE':
-			case '-B':
-			case '-BIG':
 			case '-BLOCKQUOTE':
 			case '-BODY':
 			case '-BR':
-			case '-BUTTON':
-			case '-CENTER':
-			case '-CODE':
 			case '-DD':
-			case '-DETAILS':
-			case '-DIALOG':
-			case '-DIR':
-			case '-DIV':
-			case '-DL':
 			case '-DT':
-			case '-EM':
-			case '-FIELDSET':
-			case '-FIGCAPTION':
-			case '-FIGURE':
-			case '-FONT':
-			case '-FOOTER':
 			case '-FORM':
 			case '-H1':
 			case '-H2':
@@ -752,31 +695,15 @@ private function step_in_body() {
 			case '-H4':
 			case '-H5':
 			case '-H6':
-			case '-HEADER':
-			case '-HGROUP':
 			case '-HTML':
-			case '-I':
 			case '-LI':
 			case '-LISTING':
-			case '-MAIN':
 			case '-MARQUEE':
-			case '-MENU':
-			case '-NAV':
 			case '-NOBR':
 			case '-OBJECT':
 			case '-OL':
-			case '-P':
 			case '-PRE':
-			case '-S':
-			case '-SEARCH':
-			case '-SECTION':
-			case '-SMALL':
-			case '-STRIKE':
-			case '-STRONG':
-			case '-SUMMARY':
 			case '-TEMPLATE':
-			case '-TT':
-			case '-U':
 			case '-UL':
 				$this->last_error = self::ERROR_UNSUPPORTED;
 				throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );

From 1e92ec9919477365e88ac4f09c446f10d2a7abec Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 13 Dec 2023 19:13:50 +0100
Subject: [PATCH 03/18] Rework to use tag name

---
 .../html-api/class-wp-html-processor.php      | 193 ++++++++----------
 1 file changed, 86 insertions(+), 107 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index f7f874e86f69c..71615912a7f67 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -603,112 +603,6 @@ private function step_in_body() {
 		$op       = "{$op_sigil}{$tag_name}";
 
 		switch ( $op ) {
-			/*
-			 * These tags require special handling in the 'in body' insertion mode
-			 * but do not have special handling implemented yet.
-			 *
-			 * We throw the WP_HTML_Unsupported_Exception so we're free to implememnt
-			 * the catch-all handling for any other start and end tag.
-			 *
-			 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inbody
-			 */
-			case '+APPLET':
-			case '+AREA':
-			case '+BASE':
-			case '+BASEFONT':
-			case '+BGSOUND':
-			case '+BLOCKQUOTE':
-			case '+BODY':
-			case '+BR':
-			case '+CAPTION':
-			case '+COL':
-			case '+COLGROUP':
-			case '+DD':
-			case '+DT':
-			case '+EMBED':
-			case '+FORM':
-			case '+FRAME':
-			case '+FRAMESET':
-			case '+H1':
-			case '+H2':
-			case '+H3':
-			case '+H4':
-			case '+H5':
-			case '+H6':
-			case '+HEAD':
-			case '+HR':
-			case '+HTML':
-			case '+IFRAME':
-			case '+IMAGE':
-			case '+INPUT':
-			case '+KEYGEN':
-			case '+LI':
-			case '+LINK':
-			case '+LISTING':
-			case '+MARQUEE':
-			case '+MATH':
-			case '+META':
-			case '+NOBR':
-			case '+NOEMBED':
-			case '+NOFRAMES':
-			case '+NOSCRIPT': // scripting flag??
-			case '+OBJECT':
-			case '+OL':
-			case '+OPTGROUP':
-			case '+OPTION':
-			case '+PARAM':
-			case '+PLAINTEXT':
-			case '+PRE':
-			case '+RB':
-			case '+RP':
-			case '+RT':
-			case '+RTC':
-			case '+SCRIPT':
-			case '+SELECT':
-			case '+SOURCE':
-			case '+STYLE':
-			case '+SVG':
-			case '+TABLE':
-			case '+TBODY':
-			case '+TD':
-			case '+TEMPLATE':
-			case '+TEXTAREA':
-			case '+TFOOT':
-			case '+TH':
-			case '+THEAD':
-			case '+TITLE':
-			case '+TR':
-			case '+TRACK':
-			case '+UL':
-			case '+WBR':
-			case '+XMP':
-			case '-APPLET':
-			case '-BLOCKQUOTE':
-			case '-BODY':
-			case '-BR':
-			case '-DD':
-			case '-DT':
-			case '-FORM':
-			case '-H1':
-			case '-H2':
-			case '-H3':
-			case '-H4':
-			case '-H5':
-			case '-H6':
-			case '-HTML':
-			case '-LI':
-			case '-LISTING':
-			case '-MARQUEE':
-			case '-NOBR':
-			case '-OBJECT':
-			case '-OL':
-			case '-PRE':
-			case '-TEMPLATE':
-			case '-UL':
-				$this->last_error = self::ERROR_UNSUPPORTED;
-				throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
-
-
 			/*
 			 * > A start tag whose tag name is "button"
 			 */
@@ -968,10 +862,95 @@ private function step_in_body() {
 				// Execution should not reach here; if it does then something went wrong.
 				return false;
 
-			default:
+		}
+
+		/*
+		 * These tags require special handling in the 'in body' insertion mode
+		 * that has not been implemented yet.
+		 *
+		 * As they're implemented, they should be removed from this list. An accompanying
+		 * test should help with this.
+		 *
+		 * We throw the WP_HTML_Unsupported_Exception so we're free to implememnt
+		 * the catch-all handling for any other start and end tag.
+		 *
+		 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inbody
+		 */
+		switch ( $tag_name ) {
+			case 'APPLET':
+			case 'AREA':
+			case 'BASE':
+			case 'BASEFONT':
+			case 'BGSOUND':
+			case 'BODY':
+			case 'BR':
+			case 'CAPTION':
+			case 'COL':
+			case 'COLGROUP':
+			case 'DD':
+			case 'DT':
+			case 'EMBED':
+			case 'FORM':
+			case 'FRAME':
+			case 'FRAMESET':
+			case 'H1':
+			case 'H2':
+			case 'H3':
+			case 'H4':
+			case 'H5':
+			case 'H6':
+			case 'HEAD':
+			case 'HR':
+			case 'HTML':
+			case 'IFRAME':
+			case 'INPUT':
+			case 'KEYGEN':
+			case 'LI':
+			case 'LINK':
+			case 'LISTING':
+			case 'MARQUEE':
+			case 'MATH':
+			case 'META':
+			case 'NOBR':
+			case 'NOEMBED':
+			case 'NOFRAMES':
+			case 'NOSCRIPT':
+			case 'OBJECT':
+			case 'OL':
+			case 'OPTGROUP':
+			case 'OPTION':
+			case 'PARAM':
+			case 'PLAINTEXT':
+			case 'PRE':
+			case 'RB':
+			case 'RP':
+			case 'RT':
+			case 'RTC':
+			case 'SCRIPT':
+			case 'SELECT':
+			case 'SOURCE':
+			case 'STYLE':
+			case 'SVG':
+			case 'TABLE':
+			case 'TBODY':
+			case 'TD':
+			case 'TEMPLATE':
+			case 'TEXTAREA':
+			case 'TFOOT':
+			case 'TH':
+			case 'THEAD':
+			case 'TITLE':
+			case 'TR':
+			case 'TRACK':
+			case 'UL':
+			case 'WBR':
+			case 'XMP':
 				$this->last_error = self::ERROR_UNSUPPORTED;
 				throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
 		}
+
+		$this->last_error = self::ERROR_UNSUPPORTED;
+		throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
 	}
 
 	/*

From 31abb4340503a6c2c9c8c4a98120a1411daa1caa Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 13 Dec 2023 19:14:14 +0100
Subject: [PATCH 04/18] Add tests

---
 .../tests/html-api/wpHtmlProcessor.php        | 95 +++++++++++++++++++
 1 file changed, 95 insertions(+)

diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
index a9af5d790fc53..fe39b592cddb5 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
@@ -147,4 +147,99 @@ public function test_fails_to_reconstruct_formatting_elements() {
 		$this->assertTrue( $p->next_tag( 'EM' ), 'Could not find first EM.' );
 		$this->assertFalse( $p->next_tag( 'EM' ), 'Should have aborted before finding second EM as it required reconstructing the first EM.' );
 	}
+
+	/**
+	 * Ensures that special handling of unsupported tags is cleaned up
+	 * as handling is implemented. Otherwise there's risk of leaving special
+	 * handling (that is never reached) when tag handling is implemented.
+	 *
+	 * @dataProvider data_unsupported_special_in_body_tags
+	 *
+	 * @param string $tag_name Name of the tag to test.
+	 *
+	 * @covers WP_HTML_Processor::step_in_body
+	 */
+	public function test_step_in_body_fails_on_unsupported_tags( $tag_name ) {
+		$fragment = WP_HTML_Processor::create_fragment( '<' . $tag_name . '>' );
+		$this->assertFalse( $fragment->next_tag(), 'Should fail to find tag: ' . $tag_name . '.' );
+		$this->assertEquals( $fragment->get_last_error(), WP_HTML_Processor::ERROR_UNSUPPORTED, 'Should have unsupported last error.' );
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public function data_unsupported_special_in_body_tags() {
+		return array(
+			array( 'APPLET' ),
+			array( 'AREA' ),
+			array( 'BASE' ),
+			array( 'BASEFONT' ),
+			array( 'BGSOUND' ),
+			array( 'BODY' ),
+			array( 'BR' ),
+			array( 'CAPTION' ),
+			array( 'COL' ),
+			array( 'COLGROUP' ),
+			array( 'DD' ),
+			array( 'DT' ),
+			array( 'EMBED' ),
+			array( 'FORM' ),
+			array( 'FRAME' ),
+			array( 'FRAMESET' ),
+			array( 'H1' ),
+			array( 'H2' ),
+			array( 'H3' ),
+			array( 'H4' ),
+			array( 'H5' ),
+			array( 'H6' ),
+			array( 'HEAD' ),
+			array( 'HR' ),
+			array( 'HTML' ),
+			array( 'IFRAME' ),
+			array( 'INPUT' ),
+			array( 'KEYGEN' ),
+			array( 'LI' ),
+			array( 'LINK' ),
+			array( 'LISTING' ),
+			array( 'MARQUEE' ),
+			array( 'MATH' ),
+			array( 'META' ),
+			array( 'NOBR' ),
+			array( 'NOEMBED' ),
+			array( 'NOFRAMES' ),
+			array( 'NOSCRIPT' ),
+			array( 'OBJECT' ),
+			array( 'OL' ),
+			array( 'OPTGROUP' ),
+			array( 'OPTION' ),
+			array( 'PARAM' ),
+			array( 'PLAINTEXT' ),
+			array( 'PRE' ),
+			array( 'RB' ),
+			array( 'RP' ),
+			array( 'RT' ),
+			array( 'RTC' ),
+			array( 'SCRIPT' ),
+			array( 'SELECT' ),
+			array( 'SOURCE' ),
+			array( 'STYLE' ),
+			array( 'SVG' ),
+			array( 'TABLE' ),
+			array( 'TBODY' ),
+			array( 'TD' ),
+			array( 'TEMPLATE' ),
+			array( 'TEXTAREA' ),
+			array( 'TFOOT' ),
+			array( 'TH' ),
+			array( 'THEAD' ),
+			array( 'TITLE' ),
+			array( 'TR' ),
+			array( 'TRACK' ),
+			array( 'UL' ),
+			array( 'WBR' ),
+			array( 'XMP' ),
+		);
+	}
 }

From 2eb3c97658341a9512554923d1f9e7440ab2bd20 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 13 Dec 2023 19:18:36 +0100
Subject: [PATCH 05/18] Remove H1-H6 tests and handling (now supported)

---
 src/wp-includes/html-api/class-wp-html-processor.php | 6 ------
 tests/phpunit/tests/html-api/wpHtmlProcessor.php     | 6 ------
 2 files changed, 12 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 71615912a7f67..4d9fc86202897 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -893,12 +893,6 @@ private function step_in_body() {
 			case 'FORM':
 			case 'FRAME':
 			case 'FRAMESET':
-			case 'H1':
-			case 'H2':
-			case 'H3':
-			case 'H4':
-			case 'H5':
-			case 'H6':
 			case 'HEAD':
 			case 'HR':
 			case 'HTML':
diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
index fe39b592cddb5..21a34490ac4d5 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
@@ -188,12 +188,6 @@ public function data_unsupported_special_in_body_tags() {
 			array( 'FORM' ),
 			array( 'FRAME' ),
 			array( 'FRAMESET' ),
-			array( 'H1' ),
-			array( 'H2' ),
-			array( 'H3' ),
-			array( 'H4' ),
-			array( 'H5' ),
-			array( 'H6' ),
 			array( 'HEAD' ),
 			array( 'HR' ),
 			array( 'HTML' ),

From ade089ebbaad403e140f437fdb63c8d0b22ec5f8 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 13 Dec 2023 19:20:51 +0100
Subject: [PATCH 06/18] Add note mentioning test

---
 src/wp-includes/html-api/class-wp-html-processor.php | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 4d9fc86202897..176686140fcdd 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -869,7 +869,9 @@ private function step_in_body() {
 		 * that has not been implemented yet.
 		 *
 		 * As they're implemented, they should be removed from this list. An accompanying
-		 * test should help with this.
+		 * test should help ensure this list is maintained.
+		 *
+		 * @see Tests_HtmlApi_WpHtmlProcessor::test_step_in_body_fails_on_unsupported_tags
 		 *
 		 * We throw the WP_HTML_Unsupported_Exception so we're free to implememnt
 		 * the catch-all handling for any other start and end tag.

From 2a8fc4640c33a74b0c12699d221651fafd4758dc Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Mon, 18 Dec 2023 13:09:15 -0600
Subject: [PATCH 07/18] Add support for "any other tag" categories in IN BODY

---
 .../html-api/class-wp-html-processor.php      | 43 +++++++++++++++++++
 .../tests/html-api/wpHtmlProcessor.php        | 16 -------
 .../html-api/wpHtmlProcessorBreadcrumbs.php   |  8 ++--
 3 files changed, 47 insertions(+), 20 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 176686140fcdd..ea9e33ed2829d 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -879,6 +879,8 @@ private function step_in_body() {
 		 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inbody
 		 */
 		switch ( $tag_name ) {
+			case 'ABBR':
+			case 'ACRONYM':
 			case 'APPLET':
 			case 'AREA':
 			case 'BASE':
@@ -945,6 +947,47 @@ private function step_in_body() {
 				throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
 		}
 
+		if ( ! $this->is_tag_closer() ) {
+			// > Any other start tag.
+			$this->reconstruct_active_formatting_elements();
+			$this->insert_html_element( $this->state->current_token );
+			return true;
+		} else {
+			// > Any other end tag
+			$node = $this->state->stack_of_open_elements->current_node();
+
+			in_body_any_other_end_tag_loop:
+			if ( $tag_name === $node->node_name ) {
+				$this->generate_implied_end_tags( $tag_name );
+				if ( $node !== $this->state->stack_of_open_elements->current_node() ) {
+					// @todo Record parse error: this error doesn't impact parsing.
+				}
+				$pop_count = 0;
+				foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
+					++$pop_count;
+					if ( $node === $item ) {
+						break;
+					}
+				}
+				while ( $pop_count-- > 0 ) {
+					$this->state->stack_of_open_elements->pop();
+				}
+				return true;
+			} elseif ( self::is_special( $node->node_name ) ) {
+				// This is a parse error, ignore the token.
+				return $this->step();
+			}
+			$one_shot = false;
+			foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
+				if ( $one_shot ) {
+					$node = $item;
+					goto in_body_any_other_end_tag_loop;
+				}
+
+				$one_shot = true;
+			}
+		}
+
 		$this->last_error = self::ERROR_UNSUPPORTED;
 		throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
 	}
diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
index 21a34490ac4d5..622d52ac47871 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
@@ -60,22 +60,6 @@ public function test_get_tag_is_null_once_document_is_finished() {
 		$this->assertNull( $p->get_tag() );
 	}
 
-	/**
-	 * Ensures that if the HTML Processor encounters inputs that it can't properly handle,
-	 * that it stops processing the rest of the document. This prevents data corruption.
-	 *
-	 * @ticket 59167
-	 *
-	 * @covers WP_HTML_Processor::next_tag
-	 */
-	public function test_stops_processing_after_unsupported_elements() {
-		$p = WP_HTML_Processor::create_fragment( '<p><x-not-supported></p><p></p>' );
-		$p->next_tag( 'P' );
-		$this->assertFalse( $p->next_tag(), 'Stepped into a tag after encountering X-NOT-SUPPORTED element when it should have aborted.' );
-		$this->assertNull( $p->get_tag(), "Should have aborted processing, but still reported tag {$p->get_tag()} after properly failing to step into tag." );
-		$this->assertFalse( $p->next_tag( 'P' ), 'Stepped into normal P element after X-NOT-SUPPORTED element when it should have aborted.' );
-	}
-
 	/**
 	 * Ensures that the HTML Processor maintains its internal state through seek calls.
 	 *
diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
index 2fd852e434412..e758bf72cd2f5 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
@@ -216,10 +216,6 @@ public function data_unsupported_elements() {
 			'VIDEO',
 			'WBR',
 			'XMP', // Deprecated, use PRE instead.
-
-			// Made up elements, custom elements.
-			'X-NOT-AN-HTML-ELEMENT',
-			'HUMAN-TIME',
 		);
 
 		$data = array();
@@ -360,6 +356,10 @@ public function data_html_target_with_breadcrumbs() {
 			'H4 inside H2'                          => array( '<h2><span>Major<h4 target>Minor</h3></span>', array( 'HTML', 'BODY', 'H2', 'SPAN', 'H4' ), 1 ),
 			'H5 after unclosed H4 inside H2'        => array( '<h2><span>Major<h4>Minor</span></h3><h5 target>', array( 'HTML', 'BODY', 'H2', 'SPAN', 'H5' ), 1 ),
 			'H5 after H4 inside H2'                 => array( '<h2><span>Major<h4>Minor</h4></span></h3><h5 target>', array( 'HTML', 'BODY', 'H5' ), 1 ),
+
+			// Custom elements.
+			'WP-EMOJI'                              => array( '<div><wp-emoji target></wp-emoji></div>', array( 'HTML', 'BODY', 'DIV', 'WP-EMOJI' ), 1 ),
+			'WP-EMOJI then IMG'                     => array( '<div><wp-emoji></wp-emoji><img target></div>', array( 'HTML', 'BODY', 'DIV', 'IMG' ), 1 ),
 		);
 	}
 

From eb99542e5a638b3ef1156b9316f0b2a21fdde731 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Mon, 18 Dec 2023 14:22:26 -0600
Subject: [PATCH 08/18] Update more tests, more checks, add SARCASM

---
 .../html-api/class-wp-html-processor.php      |  3 +-
 .../tests/html-api/wpHtmlProcessor.php        |  1 +
 .../html-api/wpHtmlProcessorBreadcrumbs.php   | 70 +++++++-------
 .../wpHtmlSupportRequiredOpenElements.php     | 91 +++++--------------
 4 files changed, 58 insertions(+), 107 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index ea9e33ed2829d..4a3ccb94acf14 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -879,8 +879,6 @@ private function step_in_body() {
 		 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inbody
 		 */
 		switch ( $tag_name ) {
-			case 'ABBR':
-			case 'ACRONYM':
 			case 'APPLET':
 			case 'AREA':
 			case 'BASE':
@@ -924,6 +922,7 @@ private function step_in_body() {
 			case 'RP':
 			case 'RT':
 			case 'RTC':
+			case 'SARCASM':
 			case 'SCRIPT':
 			case 'SELECT':
 			case 'SOURCE':
diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
index 622d52ac47871..2dbd76b802959 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
@@ -199,6 +199,7 @@ public function data_unsupported_special_in_body_tags() {
 			array( 'RP' ),
 			array( 'RT' ),
 			array( 'RTC' ),
+			array( 'SARCASM' ),
 			array( 'SCRIPT' ),
 			array( 'SELECT' ),
 			array( 'SOURCE' ),
diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
index e758bf72cd2f5..9a9936a599118 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
@@ -37,14 +37,26 @@ public function test_navigates_into_normative_html_for_supported_elements( $html
 	public function data_single_tag_of_supported_elements() {
 		$supported_elements = array(
 			'A',
+			'ABBR',
+			'ACRONYM', // Neutralized
 			'ADDRESS',
 			'ARTICLE',
 			'ASIDE',
+			'AUDIO',
 			'B',
+			'BDI',
+			'BDO',
 			'BIG',
+			'BLINK', // Deprecated
 			'BUTTON',
+			'CANVAS',
 			'CENTER', // Neutralized
+			'CITE',
 			'CODE',
+			'DATA',
+			'DATALIST',
+			'DEFN',
+			'DEL',
 			'DETAILS',
 			'DIALOG',
 			'DIR',
@@ -66,19 +78,42 @@ public function data_single_tag_of_supported_elements() {
 			'HGROUP',
 			'I',
 			'IMG',
+			'INS',
+			'ISINDEX', // Deprecated
+			'KBD',
+			'LABEL',
+			'LEGEND',
 			'MAIN',
+			'MAP',
+			'MARK',
 			'MENU',
+			'METER',
+			'MULTICOL', // Deprecated
 			'NAV',
+			'NEXTID',// Deprecated
+			'OUTPUT',
 			'P',
+			'PICTURE',
+			'PROGRESS',
+			'Q',
+			'RUBY',
+			'SAMP',
 			'SEARCH',
 			'SECTION',
+			'SLOT',
 			'SMALL',
+			'SPACER', // Deprecated
 			'SPAN',
 			'STRIKE',
 			'STRONG',
+			'SUB',
 			'SUMMARY',
+			'SUP',
+			'TIME',
 			'TT',
 			'U',
+			'VAR',
+			'VIDEO',
 		);
 
 		$data = array();
@@ -121,28 +156,16 @@ public function test_fails_when_encountering_unsupported_tag( $html ) {
 	 */
 	public function data_unsupported_elements() {
 		$unsupported_elements = array(
-			'ABBR',
-			'ACRONYM', // Neutralized
 			'APPLET', // Deprecated
 			'AREA',
-			'AUDIO',
 			'BASE',
-			'BDI',
-			'BDO',
 			'BGSOUND', // Deprecated; self-closing if self-closing flag provided, otherwise normal.
-			'BLINK', // Deprecated
 			'BODY',
 			'BR',
-			'CANVAS',
 			'CAPTION',
-			'CITE',
 			'COL',
 			'COLGROUP',
-			'DATA',
-			'DATALIST',
 			'DD',
-			'DEL',
-			'DEFN',
 			'DT',
 			'EMBED',
 			'FORM',
@@ -153,23 +176,13 @@ public function data_unsupported_elements() {
 			'HTML',
 			'IFRAME',
 			'INPUT',
-			'INS',
-			'ISINDEX', // Deprecated
-			'KBD',
 			'KEYGEN', // Deprecated; void
-			'LABEL',
-			'LEGEND',
 			'LI',
 			'LINK',
 			'LISTING', // Deprecated, use PRE instead.
-			'MAP',
-			'MARK',
 			'MARQUEE', // Deprecated
 			'MATH',
 			'META',
-			'METER',
-			'MULTICOL', // Deprecated
-			'NEXTID', // Deprecated
 			'NOBR', // Neutralized
 			'NOEMBED', // Neutralized
 			'NOFRAMES', // Neutralized
@@ -178,26 +191,16 @@ public function data_unsupported_elements() {
 			'OL',
 			'OPTGROUP',
 			'OPTION',
-			'OUTPUT',
-			'PICTURE',
 			'PLAINTEXT', // Neutralized
 			'PRE',
-			'PROGRESS',
-			'Q',
 			'RB', // Neutralized
 			'RP',
 			'RT',
 			'RTC', // Neutralized
-			'RUBY',
-			'SAMP',
 			'SCRIPT',
 			'SELECT',
-			'SLOT',
 			'SOURCE',
-			'SPACER', // Deprecated
 			'STYLE',
-			'SUB',
-			'SUP',
 			'SVG',
 			'TABLE',
 			'TBODY',
@@ -207,13 +210,10 @@ public function data_unsupported_elements() {
 			'TFOOT',
 			'TH',
 			'THEAD',
-			'TIME',
 			'TITLE',
 			'TR',
 			'TRACK',
 			'UL',
-			'VAR',
-			'VIDEO',
 			'WBR',
 			'XMP', // Deprecated, use PRE instead.
 		);
diff --git a/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php b/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
index 9dbb689df0329..a66a8a689ced1 100644
--- a/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
+++ b/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
@@ -72,21 +72,14 @@ public function test_has_element_in_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements
-		$this->ensure_support_is_added_everywhere( 'MI' );
-		$this->ensure_support_is_added_everywhere( 'MO' );
-		$this->ensure_support_is_added_everywhere( 'MN' );
-		$this->ensure_support_is_added_everywhere( 'MS' );
-		$this->ensure_support_is_added_everywhere( 'MTEXT' );
-		$this->ensure_support_is_added_everywhere( 'ANNOTATION-XML' );
+		// MathML Elements.
+		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
 		 */
-		$this->ensure_support_is_added_everywhere( 'FOREIGNOBJECT' );
-		$this->ensure_support_is_added_everywhere( 'DESC' );
-		$this->ensure_support_is_added_everywhere( 'TITLE' );
+		$this->ensure_support_is_added_everywhere( 'SVG' );
 	}
 
 	/**
@@ -115,21 +108,14 @@ public function test_has_element_in_list_item_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements
-		$this->ensure_support_is_added_everywhere( 'MI' );
-		$this->ensure_support_is_added_everywhere( 'MO' );
-		$this->ensure_support_is_added_everywhere( 'MN' );
-		$this->ensure_support_is_added_everywhere( 'MS' );
-		$this->ensure_support_is_added_everywhere( 'MTEXT' );
-		$this->ensure_support_is_added_everywhere( 'ANNOTATION-XML' );
+		// MathML Elements.
+		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
 		 */
-		$this->ensure_support_is_added_everywhere( 'FOREIGNOBJECT' );
-		$this->ensure_support_is_added_everywhere( 'DESC' );
-		$this->ensure_support_is_added_everywhere( 'TITLE' );
+		$this->ensure_support_is_added_everywhere( 'SVG' );
 
 		// These elements are specific to list item scope.
 		$this->ensure_support_is_added_everywhere( 'OL' );
@@ -161,21 +147,14 @@ public function test_has_element_in_button_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements
-		$this->ensure_support_is_added_everywhere( 'MI' );
-		$this->ensure_support_is_added_everywhere( 'MO' );
-		$this->ensure_support_is_added_everywhere( 'MN' );
-		$this->ensure_support_is_added_everywhere( 'MS' );
-		$this->ensure_support_is_added_everywhere( 'MTEXT' );
-		$this->ensure_support_is_added_everywhere( 'ANNOTATION-XML' );
+		// MathML Elements.
+		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
 		 */
-		$this->ensure_support_is_added_everywhere( 'FOREIGNOBJECT' );
-		$this->ensure_support_is_added_everywhere( 'DESC' );
-		$this->ensure_support_is_added_everywhere( 'TITLE' );
+		$this->ensure_support_is_added_everywhere( 'SVG' );
 	}
 
 	/**
@@ -201,21 +180,14 @@ public function test_after_element_pop_must_maintain_p_in_button_scope_flag() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements
-		$this->ensure_support_is_added_everywhere( 'MI' );
-		$this->ensure_support_is_added_everywhere( 'MO' );
-		$this->ensure_support_is_added_everywhere( 'MN' );
-		$this->ensure_support_is_added_everywhere( 'MS' );
-		$this->ensure_support_is_added_everywhere( 'MTEXT' );
-		$this->ensure_support_is_added_everywhere( 'ANNOTATION-XML' );
+		// MathML Elements.
+		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
 		 */
-		$this->ensure_support_is_added_everywhere( 'FOREIGNOBJECT' );
-		$this->ensure_support_is_added_everywhere( 'DESC' );
-		$this->ensure_support_is_added_everywhere( 'TITLE' );
+		$this->ensure_support_is_added_everywhere( 'SVG' );
 	}
 
 	/**
@@ -241,21 +213,14 @@ public function test_after_element_push_must_maintain_p_in_button_scope_flag() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements
-		$this->ensure_support_is_added_everywhere( 'MI' );
-		$this->ensure_support_is_added_everywhere( 'MO' );
-		$this->ensure_support_is_added_everywhere( 'MN' );
-		$this->ensure_support_is_added_everywhere( 'MS' );
-		$this->ensure_support_is_added_everywhere( 'MTEXT' );
-		$this->ensure_support_is_added_everywhere( 'ANNOTATION-XML' );
+		// MathML Elements.
+		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
 		 */
-		$this->ensure_support_is_added_everywhere( 'FOREIGNOBJECT' );
-		$this->ensure_support_is_added_everywhere( 'DESC' );
-		$this->ensure_support_is_added_everywhere( 'TITLE' );
+		$this->ensure_support_is_added_everywhere( 'SVG' );
 	}
 
 	/**
@@ -280,21 +245,14 @@ public function test_has_element_in_table_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements
-		$this->ensure_support_is_added_everywhere( 'MI' );
-		$this->ensure_support_is_added_everywhere( 'MO' );
-		$this->ensure_support_is_added_everywhere( 'MN' );
-		$this->ensure_support_is_added_everywhere( 'MS' );
-		$this->ensure_support_is_added_everywhere( 'MTEXT' );
-		$this->ensure_support_is_added_everywhere( 'ANNOTATION-XML' );
+		// MathML Elements.
+		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
 		 */
-		$this->ensure_support_is_added_everywhere( 'FOREIGNOBJECT' );
-		$this->ensure_support_is_added_everywhere( 'DESC' );
-		$this->ensure_support_is_added_everywhere( 'TITLE' );
+		$this->ensure_support_is_added_everywhere( 'SVG' );
 
 		// These elements are specific to TABLE scope.
 		$this->ensure_support_is_added_everywhere( 'HTML' );
@@ -335,21 +293,14 @@ public function test_has_element_in_select_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements
-		$this->ensure_support_is_added_everywhere( 'MI' );
-		$this->ensure_support_is_added_everywhere( 'MO' );
-		$this->ensure_support_is_added_everywhere( 'MN' );
-		$this->ensure_support_is_added_everywhere( 'MS' );
-		$this->ensure_support_is_added_everywhere( 'MTEXT' );
-		$this->ensure_support_is_added_everywhere( 'ANNOTATION-XML' );
+		// MathML Elements.
+		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
 		 */
-		$this->ensure_support_is_added_everywhere( 'FOREIGNOBJECT' );
-		$this->ensure_support_is_added_everywhere( 'DESC' );
-		$this->ensure_support_is_added_everywhere( 'TITLE' );
+		$this->ensure_support_is_added_everywhere( 'SVG' );
 
 		// These elements are specific to SELECT scope.
 		$this->ensure_support_is_added_everywhere( 'OPTGROUP' );

From 7e8eb4cfb8b18cf4fe7753d5cef8742a41925df2 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Tue, 19 Dec 2023 14:49:49 -0600
Subject: [PATCH 09/18] WPCS

---
 phpcs.xml.dist                                        | 11 ++++++++++-
 .../tests/html-api/wpHtmlProcessorBreadcrumbs.php     |  2 +-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index 3defbc290a6b2..b177cf1f7a990 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -224,7 +224,7 @@
 	#############################################################################
 	SELECTIVE EXCLUSIONS
 	Exclude specific files for specific sniffs and/or exclude sub-groups in sniffs.
-	
+
 	These exclusions are listed ordered by alphabetic sniff name.
 	#############################################################################
 	-->
@@ -250,6 +250,15 @@
 		<exclude-pattern>/wp-tests-config-sample\.php</exclude-pattern>
 	</rule>
 
+	<!-- Exclude forbidding goto in the HTML Processor, which mimics algorithms that are written
+	     this way in the HTML specification, and these particular algorithms are complex and
+	     highly imperative. Avoiding the goto introduces a number of risks that could make it
+	     more difficult to maintain the relationship to the standard, lead to subtle differences
+	     in the parsing, and distance the code from its standard. -->
+	<rule ref="Generic.PHP.DiscourageGoto.Found">
+		<exclude-pattern>/wp-includes/html-api/class-wp-html-processor\.php</exclude-pattern>
+	</rule>
+
 	<!-- Exclude sample config from modernization to prevent breaking CI workflows based on WP-CLI scaffold.
 		 See: https://core.trac.wordpress.org/ticket/48082#comment:16 -->
 	<rule ref="Modernize.FunctionCalls.Dirname.FileConstant">
diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
index 9a9936a599118..b584740eefeab 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
@@ -90,7 +90,7 @@ public function data_single_tag_of_supported_elements() {
 			'METER',
 			'MULTICOL', // Deprecated
 			'NAV',
-			'NEXTID',// Deprecated
+			'NEXTID', // Deprecated
 			'OUTPUT',
 			'P',
 			'PICTURE',

From ccc297d9053c4800a5e3d88e2e0e1a089ad0c3a2 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Fri, 22 Dec 2023 18:10:50 +0100
Subject: [PATCH 10/18] Better data source descriptions

---
 .../tests/html-api/wpHtmlProcessor.php        | 126 +++++++++---------
 1 file changed, 63 insertions(+), 63 deletions(-)

diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
index 2dbd76b802959..906565e4239cd 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
@@ -156,69 +156,69 @@ public function test_step_in_body_fails_on_unsupported_tags( $tag_name ) {
 	 */
 	public function data_unsupported_special_in_body_tags() {
 		return array(
-			array( 'APPLET' ),
-			array( 'AREA' ),
-			array( 'BASE' ),
-			array( 'BASEFONT' ),
-			array( 'BGSOUND' ),
-			array( 'BODY' ),
-			array( 'BR' ),
-			array( 'CAPTION' ),
-			array( 'COL' ),
-			array( 'COLGROUP' ),
-			array( 'DD' ),
-			array( 'DT' ),
-			array( 'EMBED' ),
-			array( 'FORM' ),
-			array( 'FRAME' ),
-			array( 'FRAMESET' ),
-			array( 'HEAD' ),
-			array( 'HR' ),
-			array( 'HTML' ),
-			array( 'IFRAME' ),
-			array( 'INPUT' ),
-			array( 'KEYGEN' ),
-			array( 'LI' ),
-			array( 'LINK' ),
-			array( 'LISTING' ),
-			array( 'MARQUEE' ),
-			array( 'MATH' ),
-			array( 'META' ),
-			array( 'NOBR' ),
-			array( 'NOEMBED' ),
-			array( 'NOFRAMES' ),
-			array( 'NOSCRIPT' ),
-			array( 'OBJECT' ),
-			array( 'OL' ),
-			array( 'OPTGROUP' ),
-			array( 'OPTION' ),
-			array( 'PARAM' ),
-			array( 'PLAINTEXT' ),
-			array( 'PRE' ),
-			array( 'RB' ),
-			array( 'RP' ),
-			array( 'RT' ),
-			array( 'RTC' ),
-			array( 'SARCASM' ),
-			array( 'SCRIPT' ),
-			array( 'SELECT' ),
-			array( 'SOURCE' ),
-			array( 'STYLE' ),
-			array( 'SVG' ),
-			array( 'TABLE' ),
-			array( 'TBODY' ),
-			array( 'TD' ),
-			array( 'TEMPLATE' ),
-			array( 'TEXTAREA' ),
-			array( 'TFOOT' ),
-			array( 'TH' ),
-			array( 'THEAD' ),
-			array( 'TITLE' ),
-			array( 'TR' ),
-			array( 'TRACK' ),
-			array( 'UL' ),
-			array( 'WBR' ),
-			array( 'XMP' ),
+			'APPLET'    => array( 'APPLET' ),
+			'AREA'      => array( 'AREA' ),
+			'BASE'      => array( 'BASE' ),
+			'BASEFONT'  => array( 'BASEFONT' ),
+			'BGSOUND'   => array( 'BGSOUND' ),
+			'BODY'      => array( 'BODY' ),
+			'BR'        => array( 'BR' ),
+			'CAPTION'   => array( 'CAPTION' ),
+			'COL'       => array( 'COL' ),
+			'COLGROUP'  => array( 'COLGROUP' ),
+			'DD'        => array( 'DD' ),
+			'DT'        => array( 'DT' ),
+			'EMBED'     => array( 'EMBED' ),
+			'FORM'      => array( 'FORM' ),
+			'FRAME'     => array( 'FRAME' ),
+			'FRAMESET'  => array( 'FRAMESET' ),
+			'HEAD'      => array( 'HEAD' ),
+			'HR'        => array( 'HR' ),
+			'HTML'      => array( 'HTML' ),
+			'IFRAME'    => array( 'IFRAME' ),
+			'INPUT'     => array( 'INPUT' ),
+			'KEYGEN'    => array( 'KEYGEN' ),
+			'LI'        => array( 'LI' ),
+			'LINK'      => array( 'LINK' ),
+			'LISTING'   => array( 'LISTING' ),
+			'MARQUEE'   => array( 'MARQUEE' ),
+			'MATH'      => array( 'MATH' ),
+			'META'      => array( 'META' ),
+			'NOBR'      => array( 'NOBR' ),
+			'NOEMBED'   => array( 'NOEMBED' ),
+			'NOFRAMES'  => array( 'NOFRAMES' ),
+			'NOSCRIPT'  => array( 'NOSCRIPT' ),
+			'OBJECT'    => array( 'OBJECT' ),
+			'OL'        => array( 'OL' ),
+			'OPTGROUP'  => array( 'OPTGROUP' ),
+			'OPTION'    => array( 'OPTION' ),
+			'PARAM'     => array( 'PARAM' ),
+			'PLAINTEXT' => array( 'PLAINTEXT' ),
+			'PRE'       => array( 'PRE' ),
+			'RB'        => array( 'RB' ),
+			'RP'        => array( 'RP' ),
+			'RT'        => array( 'RT' ),
+			'RTC'       => array( 'RTC' ),
+			'SARCASM'   => array( 'SARCASM' ),
+			'SCRIPT'    => array( 'SCRIPT' ),
+			'SELECT'    => array( 'SELECT' ),
+			'SOURCE'    => array( 'SOURCE' ),
+			'STYLE'     => array( 'STYLE' ),
+			'SVG'       => array( 'SVG' ),
+			'TABLE'     => array( 'TABLE' ),
+			'TBODY'     => array( 'TBODY' ),
+			'TD'        => array( 'TD' ),
+			'TEMPLATE'  => array( 'TEMPLATE' ),
+			'TEXTAREA'  => array( 'TEXTAREA' ),
+			'TFOOT'     => array( 'TFOOT' ),
+			'TH'        => array( 'TH' ),
+			'THEAD'     => array( 'THEAD' ),
+			'TITLE'     => array( 'TITLE' ),
+			'TR'        => array( 'TR' ),
+			'TRACK'     => array( 'TRACK' ),
+			'UL'        => array( 'UL' ),
+			'WBR'       => array( 'WBR' ),
+			'XMP'       => array( 'XMP' ),
 		);
 	}
 }

From b20806af5958309892584b389075e3816c4529c3 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Fri, 22 Dec 2023 18:13:56 +0100
Subject: [PATCH 11/18] Close tags so processing doesn't pause

---
 tests/phpunit/tests/html-api/wpHtmlProcessor.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
index 906565e4239cd..2e70bee2196aa 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
@@ -144,7 +144,7 @@ public function test_fails_to_reconstruct_formatting_elements() {
 	 * @covers WP_HTML_Processor::step_in_body
 	 */
 	public function test_step_in_body_fails_on_unsupported_tags( $tag_name ) {
-		$fragment = WP_HTML_Processor::create_fragment( '<' . $tag_name . '>' );
+		$fragment = WP_HTML_Processor::create_fragment( '<' . $tag_name . '></' . $tag_name . '>' );
 		$this->assertFalse( $fragment->next_tag(), 'Should fail to find tag: ' . $tag_name . '.' );
 		$this->assertEquals( $fragment->get_last_error(), WP_HTML_Processor::ERROR_UNSUPPORTED, 'Should have unsupported last error.' );
 	}

From 556f3cf8a012ad789728045ccb44cc398244ae43 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Mon, 18 Dec 2023 15:57:43 -0600
Subject: [PATCH 12/18] Fix bugs uncovered by tests

---
 src/wp-includes/html-api/class-wp-html-processor.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 4a3ccb94acf14..70448345d9aa0 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1387,7 +1387,7 @@ private function run_adoption_agency_algorithm() {
 
 			// > If formatting element is not in the stack of open elements, then this is a parse error; remove the element from the list, and return.
 			if ( ! $this->state->stack_of_open_elements->contains_node( $formatting_element ) ) {
-				$this->state->active_formatting_elements->remove_node( $formatting_element->bookmark_name );
+				$this->state->active_formatting_elements->remove_node( $formatting_element );
 				return;
 			}
 

From 2cab6cf3250f284c3acec22f4330a41f98416eca Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Fri, 22 Dec 2023 15:01:36 -0600
Subject: [PATCH 13/18] Refactor closing tag loop, eliminate goto

---
 phpcs.xml.dist                                |  9 ----
 .../html-api/class-wp-html-processor.php      | 47 +++++++++----------
 2 files changed, 22 insertions(+), 34 deletions(-)

diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index b177cf1f7a990..fabbe2ef7d520 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -250,15 +250,6 @@
 		<exclude-pattern>/wp-tests-config-sample\.php</exclude-pattern>
 	</rule>
 
-	<!-- Exclude forbidding goto in the HTML Processor, which mimics algorithms that are written
-	     this way in the HTML specification, and these particular algorithms are complex and
-	     highly imperative. Avoiding the goto introduces a number of risks that could make it
-	     more difficult to maintain the relationship to the standard, lead to subtle differences
-	     in the parsing, and distance the code from its standard. -->
-	<rule ref="Generic.PHP.DiscourageGoto.Found">
-		<exclude-pattern>/wp-includes/html-api/class-wp-html-processor\.php</exclude-pattern>
-	</rule>
-
 	<!-- Exclude sample config from modernization to prevent breaking CI workflows based on WP-CLI scaffold.
 		 See: https://core.trac.wordpress.org/ticket/48082#comment:16 -->
 	<rule ref="Modernize.FunctionCalls.Dirname.FileConstant">
diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 70448345d9aa0..fcada612d4166 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -953,37 +953,34 @@ private function step_in_body() {
 			return true;
 		} else {
 			// > Any other end tag
-			$node = $this->state->stack_of_open_elements->current_node();
 
-			in_body_any_other_end_tag_loop:
-			if ( $tag_name === $node->node_name ) {
-				$this->generate_implied_end_tags( $tag_name );
-				if ( $node !== $this->state->stack_of_open_elements->current_node() ) {
-					// @todo Record parse error: this error doesn't impact parsing.
-				}
-				$pop_count = 0;
-				foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
-					++$pop_count;
-					if ( $node === $item ) {
-						break;
-					}
+			/*
+			 * Find the corresponding tag opener in the stack of open elements, if
+			 * it exists before reaching a special element, which provides a kind
+			 * of boundary in the stack. For example, a `</custom-tag>` should not
+			 * close anything beyond its containing `P` or `DIV` element.
+			 */
+			foreach ( $this->state->stack_of_open_elements->walk_up() as $node ) {
+				if ( $tag_name === $node->node_name ) {
+					break;
 				}
-				while ( $pop_count-- > 0 ) {
-					$this->state->stack_of_open_elements->pop();
+
+				if ( self::is_special( $node->node_name ) ) {
+					// This is a parse error, ignore the token.
+					return $this->step();
 				}
-				return true;
-			} elseif ( self::is_special( $node->node_name ) ) {
-				// This is a parse error, ignore the token.
-				return $this->step();
 			}
-			$one_shot = false;
+
+			$this->generate_implied_end_tags( $tag_name );
+			if ( $node !== $this->state->stack_of_open_elements->current_node() ) {
+				// @todo Record parse error: this error doesn't impact parsing.
+			}
+
 			foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
-				if ( $one_shot ) {
-					$node = $item;
-					goto in_body_any_other_end_tag_loop;
+				$this->state->stack_of_open_elements->pop();
+				if ( $node === $item ) {
+					return true;
 				}
-
-				$one_shot = true;
 			}
 		}
 

From 98c46e9aad0201e3d8b9c9d720972b68e566ffa1 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Fri, 22 Dec 2023 15:08:42 -0600
Subject: [PATCH 14/18] Undo whitespace change in phpcs rules

---
 phpcs.xml.dist | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index fabbe2ef7d520..3defbc290a6b2 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -224,7 +224,7 @@
 	#############################################################################
 	SELECTIVE EXCLUSIONS
 	Exclude specific files for specific sniffs and/or exclude sub-groups in sniffs.
-
+	
 	These exclusions are listed ordered by alphabetic sniff name.
 	#############################################################################
 	-->

From 620bdec71e9b5774c8c154eb5fb916481d4f6c07 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Fri, 22 Dec 2023 15:16:43 -0600
Subject: [PATCH 15/18] Update comments, remove redundant code.

---
 .../html-api/class-wp-html-processor.php      | 55 +++++--------------
 1 file changed, 13 insertions(+), 42 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index fcada612d4166..72a3c30fb0794 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -830,51 +830,21 @@ private function step_in_body() {
 				$this->reconstruct_active_formatting_elements();
 				$this->insert_html_element( $this->state->current_token );
 				return true;
-
-			/*
-			 * > Any other start tag
-			 */
-			case '+SPAN':
-				$this->reconstruct_active_formatting_elements();
-				$this->insert_html_element( $this->state->current_token );
-				return true;
-
-			/*
-			 * Any other end tag
-			 */
-			case '-SPAN':
-				foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
-					// > If node is an HTML element with the same tag name as the token, then:
-					if ( $item->node_name === $tag_name ) {
-						$this->generate_implied_end_tags( $tag_name );
-
-						// > If node is not the current node, then this is a parse error.
-
-						$this->state->stack_of_open_elements->pop_until( $tag_name );
-						return true;
-					}
-
-					// > Otherwise, if node is in the special category, then this is a parse error; ignore the token, and return.
-					if ( self::is_special( $item->node_name ) ) {
-						return $this->step();
-					}
-				}
-				// Execution should not reach here; if it does then something went wrong.
-				return false;
-
 		}
 
 		/*
 		 * These tags require special handling in the 'in body' insertion mode
-		 * that has not been implemented yet.
+		 * but that handling hasn't yet been implemented.
 		 *
-		 * As they're implemented, they should be removed from this list. An accompanying
-		 * test should help ensure this list is maintained.
+		 * As the rules for each tag are implemented, the corresponding tag
+		 * name should be removed from this list. An accompanying test should
+		 * help ensure this list is maintained.
 		 *
 		 * @see Tests_HtmlApi_WpHtmlProcessor::test_step_in_body_fails_on_unsupported_tags
 		 *
-		 * We throw the WP_HTML_Unsupported_Exception so we're free to implememnt
-		 * the catch-all handling for any other start and end tag.
+		 * Since this switch structure throws a WP_HTML_Unsupported_Exception, it's
+		 * possible to handle "any other start tag" and "any other end tag" below,
+		 * as that guarantees execution doesn't proceed for the unimplemented tags.
 		 *
 		 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inbody
 		 */
@@ -947,12 +917,16 @@ private function step_in_body() {
 		}
 
 		if ( ! $this->is_tag_closer() ) {
-			// > Any other start tag.
+			/*
+			 * > Any other start tag
+			 */
 			$this->reconstruct_active_formatting_elements();
 			$this->insert_html_element( $this->state->current_token );
 			return true;
 		} else {
-			// > Any other end tag
+			/*
+			 * > Any other end tag
+			 */
 
 			/*
 			 * Find the corresponding tag opener in the stack of open elements, if
@@ -983,9 +957,6 @@ private function step_in_body() {
 				}
 			}
 		}
-
-		$this->last_error = self::ERROR_UNSUPPORTED;
-		throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
 	}
 
 	/*

From a98f30bb943cbefe568fc654b3697d882a29581b Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Fri, 22 Dec 2023 15:55:37 -0600
Subject: [PATCH 16/18] Add newly-supported elements to docblock, fix typo in
 tests.

---
 src/wp-includes/html-api/class-wp-html-processor.php     | 9 ++++++---
 .../tests/html-api/wpHtmlProcessorBreadcrumbs.php        | 2 +-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 72a3c30fb0794..3263ffe1dc90a 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -100,15 +100,18 @@
  * The following list specifies the HTML tags that _are_ supported:
  *
  *  - Containers: ADDRESS, BLOCKQUOTE, DETAILS, DIALOG, DIV, FOOTER, HEADER, MAIN, MENU, SPAN, SUMMARY.
- *  - Form elements: BUTTON, FIELDSET, SEARCH.
+ *  - Form elements: BUTTON, DATALIST, FIELDSET, LABEL, LEGEND, METER, PROGRESS, SEARCH.
  *  - Formatting elements: B, BIG, CODE, EM, FONT, I, SMALL, STRIKE, STRONG, TT, U.
  *  - Heading elements: H1, H2, H3, H4, H5, H6, HGROUP.
  *  - Links: A.
  *  - Lists: DL.
- *  - Media elements: FIGCAPTION, FIGURE, IMG.
+ *  - Media elements: AUDIO, CANVAS, FIGCAPTION, FIGURE, IMG, MAP, PICTURE, VIDEO.
  *  - Paragraph: P.
+ *  - Phrasing elements: ABBR, BDI, BDO, CITE, DATA, DEL, DFN, INS, MARK, OUTPUT, Q, SAMP, SUB, SUP, TIME, VAR
  *  - Sectioning elements: ARTICLE, ASIDE, NAV, SECTION
- *  - Deprecated elements: CENTER, DIR
+ *  - Templating elements: SLOT
+ *  - Text decoration: RUBY
+ *  - Deprecated elements: ACRONYM, BLINK, CENTER, DIR, ISINDEX, MULTICOL, NEXTID, SPACER
  *
  * ### Supported markup
  *
diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
index b584740eefeab..3b339e4f82ee9 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
@@ -55,7 +55,7 @@ public function data_single_tag_of_supported_elements() {
 			'CODE',
 			'DATA',
 			'DATALIST',
-			'DEFN',
+			'DFN',
 			'DEL',
 			'DETAILS',
 			'DIALOG',

From 9f9ce0d7e960e777f761cff7bd71944d2eb44806 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Fri, 22 Dec 2023 15:57:26 -0600
Subject: [PATCH 17/18] fixup! Add newly-supported elements to docblock, fix
 typo in tests.

---
 src/wp-includes/html-api/class-wp-html-processor.php | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 3263ffe1dc90a..41823af00ff93 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -100,6 +100,7 @@
  * The following list specifies the HTML tags that _are_ supported:
  *
  *  - Containers: ADDRESS, BLOCKQUOTE, DETAILS, DIALOG, DIV, FOOTER, HEADER, MAIN, MENU, SPAN, SUMMARY.
+ *  - Custom elements: All custom elements are supported. :)
  *  - Form elements: BUTTON, DATALIST, FIELDSET, LABEL, LEGEND, METER, PROGRESS, SEARCH.
  *  - Formatting elements: B, BIG, CODE, EM, FONT, I, SMALL, STRIKE, STRONG, TT, U.
  *  - Heading elements: H1, H2, H3, H4, H5, H6, HGROUP.
@@ -107,11 +108,11 @@
  *  - Lists: DL.
  *  - Media elements: AUDIO, CANVAS, FIGCAPTION, FIGURE, IMG, MAP, PICTURE, VIDEO.
  *  - Paragraph: P.
- *  - Phrasing elements: ABBR, BDI, BDO, CITE, DATA, DEL, DFN, INS, MARK, OUTPUT, Q, SAMP, SUB, SUP, TIME, VAR
- *  - Sectioning elements: ARTICLE, ASIDE, NAV, SECTION
- *  - Templating elements: SLOT
- *  - Text decoration: RUBY
- *  - Deprecated elements: ACRONYM, BLINK, CENTER, DIR, ISINDEX, MULTICOL, NEXTID, SPACER
+ *  - Phrasing elements: ABBR, BDI, BDO, CITE, DATA, DEL, DFN, INS, MARK, OUTPUT, Q, SAMP, SUB, SUP, TIME, VAR.
+ *  - Sectioning elements: ARTICLE, ASIDE, NAV, SECTION.
+ *  - Templating elements: SLOT.
+ *  - Text decoration: RUBY.
+ *  - Deprecated elements: ACRONYM, BLINK, CENTER, DIR, ISINDEX, MULTICOL, NEXTID, SPACER.
  *
  * ### Supported markup
  *

From 3f9670a5573a53334cfec7803c1839a1c22621b5 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Fri, 22 Dec 2023 19:40:41 -0600
Subject: [PATCH 18/18] Update docblock lints and re-add MathML and SVG
 comments.

---
 .../tests/html-api/wpHtmlProcessor.php        |  6 ++--
 .../wpHtmlSupportRequiredOpenElements.php     | 28 ++++++++++++++-----
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
index 2e70bee2196aa..2e5565c9734fa 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
@@ -137,11 +137,13 @@ public function test_fails_to_reconstruct_formatting_elements() {
 	 * as handling is implemented. Otherwise there's risk of leaving special
 	 * handling (that is never reached) when tag handling is implemented.
 	 *
-	 * @dataProvider data_unsupported_special_in_body_tags
+	 * @ticket 60092
 	 *
-	 * @param string $tag_name Name of the tag to test.
+	 * @dataProvider data_unsupported_special_in_body_tags
 	 *
 	 * @covers WP_HTML_Processor::step_in_body
+	 *
+	 * @param string $tag_name Name of the tag to test.
 	 */
 	public function test_step_in_body_fails_on_unsupported_tags( $tag_name ) {
 		$fragment = WP_HTML_Processor::create_fragment( '<' . $tag_name . '></' . $tag_name . '>' );
diff --git a/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php b/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
index a66a8a689ced1..a0c9c600c1e45 100644
--- a/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
+++ b/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
@@ -72,12 +72,14 @@ public function test_has_element_in_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements.
+		// MathML Elements: MI, MO, MN, MS, MTEXT, ANNOTATION-XML.
 		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
+		 *
+		 * FOREIGNOBJECT, DESC, TITLE.
 		 */
 		$this->ensure_support_is_added_everywhere( 'SVG' );
 	}
@@ -108,12 +110,14 @@ public function test_has_element_in_list_item_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements.
+		// MathML Elements: MI, MO, MN, MS, MTEXT, ANNOTATION-XML.
 		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
+		 *
+		 * FOREIGNOBJECT, DESC, TITLE.
 		 */
 		$this->ensure_support_is_added_everywhere( 'SVG' );
 
@@ -147,12 +151,14 @@ public function test_has_element_in_button_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements.
+		// MathML Elements: MI, MO, MN, MS, MTEXT, ANNOTATION-XML.
 		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
+		 *
+		 * FOREIGNOBJECT, DESC, TITLE.
 		 */
 		$this->ensure_support_is_added_everywhere( 'SVG' );
 	}
@@ -180,12 +186,14 @@ public function test_after_element_pop_must_maintain_p_in_button_scope_flag() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements.
+		// MathML Elements: MI, MO, MN, MS, MTEXT, ANNOTATION-XML.
 		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
+		 *
+		 * FOREIGNOBJECT, DESC, TITLE.
 		 */
 		$this->ensure_support_is_added_everywhere( 'SVG' );
 	}
@@ -213,12 +221,14 @@ public function test_after_element_push_must_maintain_p_in_button_scope_flag() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements.
+		// MathML Elements: MI, MO, MN, MS, MTEXT, ANNOTATION-XML.
 		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
+		 *
+		 * FOREIGNOBJECT, DESC, TITLE.
 		 */
 		$this->ensure_support_is_added_everywhere( 'SVG' );
 	}
@@ -245,12 +255,14 @@ public function test_has_element_in_table_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements.
+		// MathML Elements: MI, MO, MN, MS, MTEXT, ANNOTATION-XML.
 		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
+		 *
+		 * FOREIGNOBJECT, DESC, TITLE.
 		 */
 		$this->ensure_support_is_added_everywhere( 'SVG' );
 
@@ -293,12 +305,14 @@ public function test_has_element_in_select_scope_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'OBJECT' );
 		$this->ensure_support_is_added_everywhere( 'TEMPLATE' );
 
-		// MathML Elements.
+		// MathML Elements: MI, MO, MN, MS, MTEXT, ANNOTATION-XML.
 		$this->ensure_support_is_added_everywhere( 'MATH' );
 
 		/*
 		 * SVG elements: note that TITLE is both an HTML element and an SVG element
 		 * so care must be taken when adding support for either one.
+		 *
+		 * FOREIGNOBJECT, DESC, TITLE.
 		 */
 		$this->ensure_support_is_added_everywhere( 'SVG' );