64643 Remove some obsolete return by refs

[nirav7707]

Core ticket: https://core.trac.wordpress.org/ticket/64643

[github-actions]

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[westonruter]

Take it or leave it, but Gemini CLI found some additional possibilities:

diff --git a/src/wp-admin/includes/class-wp-upgrader-skin.php b/src/wp-admin/includes/class-wp-upgrader-skin.php
index 831da3aeba..4c1615cdd2 100644
--- a/src/wp-admin/includes/class-wp-upgrader-skin.php
+++ b/src/wp-admin/includes/class-wp-upgrader-skin.php
@@ -83,9 +83,9 @@ class WP_Upgrader_Skin {
 	 *
 	 * @param WP_Upgrader $upgrader
 	 */
-	public function set_upgrader( &$upgrader ) {
+	public function set_upgrader( $upgrader ) {
 		if ( is_object( $upgrader ) ) {
-			$this->upgrader =& $upgrader;
+			$this->upgrader = $upgrader;
 		}
 		$this->add_strings();
 	}
diff --git a/src/wp-includes/class-wp-hook.php b/src/wp-includes/class-wp-hook.php
index cd6860c0f8..cf6f5aeaca 100644
--- a/src/wp-includes/class-wp-hook.php
+++ b/src/wp-includes/class-wp-hook.php
@@ -375,9 +375,9 @@ final class WP_Hook implements Iterator, ArrayAccess {
 	 *
 	 * @since 4.7.0
 	 *
-	 * @param array $args Arguments to pass to the hook callbacks. Passed by reference.
+	 * @param array $args Arguments to pass to the hook callbacks.
 	 */
-	public function do_all_hook( &$args ) {
+	public function do_all_hook( $args ) {
 		$nesting_level                      = $this->nesting_level++;
 		$this->iterations[ $nesting_level ] = $this->priorities;
 
diff --git a/src/wp-includes/deprecated.php b/src/wp-includes/deprecated.php
index 390d632492..897b1a48a3 100644
--- a/src/wp-includes/deprecated.php
+++ b/src/wp-includes/deprecated.php
@@ -3111,7 +3111,7 @@ function get_theme_data( $theme_file ) {
  *
  * @param array $pages list of page objects
  */
-function update_page_cache( &$pages ) {
+function update_page_cache( $pages ) {
 	_deprecated_function( __FUNCTION__, '3.4.0', 'update_post_cache()' );
 
 	update_post_cache( $pages );
@@ -3177,9 +3177,9 @@ function sticky_class( $post_id = null ) {
  * @deprecated 3.5.0 Use get_post_ancestors()
  * @see get_post_ancestors()
  *
- * @param WP_Post $post Post object, passed by reference (unused).
+ * @param WP_Post $post Post object (unused).
  */
-function _get_post_ancestors( &$post ) {
+function _get_post_ancestors( $post ) {
 	_deprecated_function( __FUNCTION__, '3.5.0' );
 }
 
diff --git a/src/wp-includes/nav-menu-template.php b/src/wp-includes/nav-menu-template.php
index d90fdfa806..29d8a03944 100644
--- a/src/wp-includes/nav-menu-template.php
+++ b/src/wp-includes/nav-menu-template.php
@@ -324,7 +324,7 @@ function wp_nav_menu( $args = array() ) {
  *
  * @param array $menu_items The current menu item objects to which to add the class property information.
  */
-function _wp_menu_item_classes_by_context( &$menu_items ) {
+function _wp_menu_item_classes_by_context( $menu_items ) {
 	global $wp_query, $wp_rewrite;
 
 	$queried_object    = $wp_query->get_queried_object();
diff --git a/src/wp-includes/pomo/entry.php b/src/wp-includes/pomo/entry.php
index e1b1c8f8c8..48c52384b1 100644
--- a/src/wp-includes/pomo/entry.php
+++ b/src/wp-includes/pomo/entry.php
@@ -114,7 +114,7 @@ if ( ! class_exists( 'Translation_Entry', false ) ) :
 		 *
 		 * @param Translation_Entry $other Other translation entry.
 		 */
-		public function merge_with( &$other ) {
+		public function merge_with( $other ) {
 			$this->flags      = array_unique( array_merge( $this->flags, $other->flags ) );
 			$this->references = array_unique( array_merge( $this->references, $other->references ) );
 			if ( $this->extracted_comments !== $other->extracted_comments ) {
diff --git a/src/wp-includes/pomo/po.php b/src/wp-includes/pomo/po.php
index de1bc92064..594ad80f4e 100644
--- a/src/wp-includes/pomo/po.php
+++ b/src/wp-includes/pomo/po.php
@@ -486,7 +486,7 @@ if ( ! class_exists( 'PO', false ) ) :
 		 * @param Translation_Entry $entry
 		 * @param string            $po_comment_line
 		 */
-		public function add_comment_to_entry( &$entry, $po_comment_line ) {
+		public function add_comment_to_entry( $entry, $po_comment_line ) {
 			$first_two = substr( $po_comment_line, 0, 2 );
 			$comment   = trim( substr( $po_comment_line, 2 ) );
 			if ( '#:' === $first_two ) {
diff --git a/src/wp-includes/pomo/translations.php b/src/wp-includes/pomo/translations.php
index c4a9ba72d6..8d1a2183b9 100644
--- a/src/wp-includes/pomo/translations.php
+++ b/src/wp-includes/pomo/translations.php
@@ -130,7 +130,7 @@ if ( ! class_exists( 'Translations', false ) ) :
 		 * @param Translation_Entry $entry Translation entry.
 		 * @return Translation_Entry|false Translation entry if it exists, false otherwise.
 		 */
-		public function translate_entry( &$entry ) {
+		public function translate_entry( $entry ) {
 			$key = $entry->key();
 			return $this->entries[ $key ] ?? false;
 		}
@@ -220,9 +220,9 @@ if ( ! class_exists( 'Translations', false ) ) :
 		 *
 		 * @since 2.8.0
 		 *
-		 * @param Translations $other Another Translation object, whose translations will be merged in this one (passed by reference).
+		 * @param Translations $other Another Translation object, whose translations will be merged in this one.
 		 */
-		public function merge_with( &$other ) {
+		public function merge_with( $other ) {
 			foreach ( $other->entries as $entry ) {
 				$this->entries[ $entry->key() ] = $entry;
 			}
@@ -235,7 +235,7 @@ if ( ! class_exists( 'Translations', false ) ) :
 		 *
 		 * @param Translations $other
 		 */
-		public function merge_originals_with( &$other ) {
+		public function merge_originals_with( $other ) {
 			foreach ( $other->entries as $entry ) {
 				if ( ! isset( $this->entries[ $entry->key() ] ) ) {
 					$this->entries[ $entry->key() ] = $entry;
diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index f4b06958e0..cb7a91d56c 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -6309,10 +6309,10 @@ function get_page_hierarchy( $pages, $page_id = 0 ) {
  * @see _page_traverse_name()
  *
  * @param int      $page_id  Page ID.
- * @param array    $children Parent-children relations (passed by reference).
+ * @param array    $children Parent-children relations.
  * @param string[] $result   Array of page names keyed by ID (passed by reference).
  */
-function _page_traverse_name( $page_id, &$children, &$result ) {
+function _page_traverse_name( $page_id, $children, &$result ) {
 	if ( isset( $children[ $page_id ] ) ) {
 		foreach ( (array) $children[ $page_id ] as $child ) {
 			$result[ $child->ID ] = $child->post_name;
@@ -7678,9 +7678,9 @@ function _get_last_post_time( $timezone, $field, $post_type = 'any' ) {
  *
  * @since 1.5.1
  *
- * @param WP_Post[] $posts Array of post objects (passed by reference).
+ * @param WP_Post[] $posts Array of post objects.
  */
-function update_post_cache( &$posts ) {
+function update_post_cache( $posts ) {
 	if ( ! $posts ) {
 		return;
 	}
@@ -7762,12 +7762,12 @@ function clean_post_cache( $post ) {
  *
  * @since 1.5.0
  *
- * @param WP_Post[] $posts             Array of post objects (passed by reference).
+ * @param WP_Post[] $posts             Array of post objects.
  * @param string    $post_type         Optional. Post type. Default 'post'.
  * @param bool      $update_term_cache Optional. Whether to update the term cache. Default true.
  * @param bool      $update_meta_cache Optional. Whether to update the meta cache. Default true.
  */
-function update_post_caches( &$posts, $post_type = 'post', $update_term_cache = true, $update_meta_cache = true ) {
+function update_post_caches( $posts, $post_type = 'post', $update_term_cache = true, $update_meta_cache = true ) {
 	// No point in doing all this work if we didn't match any posts.
 	if ( ! $posts ) {
 		return;

[nirav7707]

@westonruter Thanks, I have a plan to remove the ref passed parameter in phase-wise, based on the ticket. I have started with the changes done on mentioed changeset. Next, plan to scan the whole core codebase.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props niravsherasiya7707, westonruter.

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[nirav7707]

Note: E2E tests are failing for all the latest PRs.

[Copilot]

Pull request overview

This pull request removes obsolete pass-by-reference (&) parameters from various WordPress core functions and methods. The changes modernize the codebase by removing unnecessary reference semantics that were redundant due to PHP's object handling behavior, where objects are always passed by reference.

Changes:

• Removed pass-by-reference from function signatures where parameters are only read or where object properties are modified (objects are inherently passed by reference in PHP)
• Updated corresponding documentation to remove "(passed by reference)" notes
• Removed unnecessary reference assignments in internal array operations

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/wp-includes/revision.php	Removed unnecessary & from wp_get_post_revision() parameter
src/wp-includes/post.php	Removed & from get_page_hierarchy(), _page_traverse_name() (except $result which correctly remains by-ref), update_post_cache(), and update_post_caches()
src/wp-includes/pomo/translations.php	Removed & from translation class methods: translate_entry(), merge_with(), merge_originals_with()
src/wp-includes/pomo/po.php	Removed & from add_comment_to_entry() method
src/wp-includes/pomo/entry.php	Removed & from merge_with() method
src/wp-includes/nav-menu-template.php	Removed & from _wp_menu_item_classes_by_context()
src/wp-includes/deprecated.php	Removed & from deprecated functions update_page_cache() and _get_post_ancestors()
src/wp-includes/comment.php	Removed & from separate_comments() and internal reference assignments
src/wp-includes/class-wp-hook.php	Removed & from do_all_hook() method
src/wp-admin/includes/class-wp-upgrader-skin.php	Removed & from set_upgrader() method and property assignment

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