Users: Share current user instance across functions.

Share the `WP_User` instance for the current user between the functions `get_userdata()` and `wp_get_current_user()`. Both functions return the `$current_user` global for the current user.

Force refresh the `$current_user` global within `clean_user_cache()` by immediately re-calling `wp_set_current_user()` with the current user's ID. This ensures any changes to the current user's permissions or other settings are reflected in the global. As a side-effect this immediately rewarms the current user's cache.

Props chaion07, chriscct7, donmhico, hellofromtonya, lukecarbis, peterwilsoncc, rmccue, TimothyBlynJacobs.
Fixes #28020.

Built from https://develop.svn.wordpress.org/trunk@50790


git-svn-id: http://core.svn.wordpress.org/trunk@50399 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/pluggable.php

@@ -91,18 +91,25 @@ if ( ! function_exists( 'get_user_by' ) ) :
 	 *
 	 * @since 2.8.0
 	 * @since 4.4.0 Added 'ID' as an alias of 'id' for the `$field` parameter.
+	 * @since 5.8.0 Returns the global `$current_user` if it's the user being fetched.
 	 *
 	 * @param string     $field The field to retrieve the user with. id | ID | slug | email | login.
 	 * @param int|string $value A value for $field. A user ID, slug, email address, or login name.
 	 * @return WP_User|false WP_User object on success, false on failure.
 	 */
 	function get_user_by( $field, $value ) {
+		global $current_user;
+
 		$userdata = WP_User::get_data_by( $field, $value );
 
 		if ( ! $userdata ) {
 			return false;
 		}
 
+		if ( $current_user instanceof WP_User && $current_user->ID === (int) $userdata->ID ) {
+			return $current_user;
+		}
+
 		$user = new WP_User;
 		$user->init( $userdata );
 

wp-includes/user.php

@@ -1561,10 +1561,15 @@ function update_user_caches( $user ) {
  *
  * @since 3.0.0
  * @since 4.4.0 'clean_user_cache' action was added.
+ * @since 5.8.0 Refreshes the global user instance if cleaning the user cache for the current user.
+ *
+ * @global WP_User $current_user The current user object which holds the user data.
  *
  * @param WP_User|int $user User object or ID to be cleaned from the cache
  */
 function clean_user_cache( $user ) {
+	global $current_user;
+
 	if ( is_numeric( $user ) ) {
 		$user = new WP_User( $user );
 	}
@@ -1587,6 +1592,13 @@ function clean_user_cache( $user ) {
 	 * @param WP_User $user    User object.
 	 */
 	do_action( 'clean_user_cache', $user->ID, $user );
+
+	// Refresh the global user instance if the cleaning current user.
+	if ( get_current_user_id() === (int) $user->ID ) {
+		$user_id      = (int) $user->ID;
+		$current_user = null;
+		wp_set_current_user( $user_id, '' );
+	}
 }
 
 /**

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-50789';
+$wp_version = '5.8-alpha-50790';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.