Database: Remove back-compat for database servers that don't support `utf8mb4`.

Since WordPress 6.5, the minimum supported version of MySQL and MariaDB is 5.5.5. This means all supported database servers now support the `utf8mb4` character set and therefore the conditional logic for this is no longer necessary.

Props l1nuxjedi, craigfrancis, OllieJones, johnbillion

Fixes #60096

Built from https://develop.svn.wordpress.org/trunk@57926


git-svn-id: http://core.svn.wordpress.org/trunk@57427 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-site-health.php

@@ -1283,120 +1283,6 @@ class WP_Site_Health {
 		return $result;
 	}
 
-	/**
-	 * Tests if the database server is capable of using utf8mb4.
-	 *
-	 * @since 5.2.0
-	 *
-	 * @return array The test results.
-	 */
-	public function get_test_utf8mb4_support() {
-		if ( ! $this->mysql_server_version ) {
-			$this->prepare_sql_data();
-		}
-
-		$result = array(
-			'label'       => __( 'UTF8MB4 is supported' ),
-			'status'      => 'good',
-			'badge'       => array(
-				'label' => __( 'Performance' ),
-				'color' => 'blue',
-			),
-			'description' => sprintf(
-				'<p>%s</p>',
-				__( 'UTF8MB4 is the character set WordPress prefers for database storage because it safely supports the widest set of characters and encodings, including Emoji, enabling better support for non-English languages.' )
-			),
-			'actions'     => '',
-			'test'        => 'utf8mb4_support',
-		);
-
-		if ( ! $this->is_mariadb ) {
-			if ( version_compare( $this->mysql_server_version, '5.5.3', '<' ) ) {
-				$result['status'] = 'recommended';
-
-				$result['label'] = __( 'utf8mb4 requires a MySQL update' );
-
-				$result['description'] .= sprintf(
-					'<p>%s</p>',
-					sprintf(
-						/* translators: %s: Version number. */
-						__( 'WordPress&#8217; utf8mb4 support requires MySQL version %s or greater. Please contact your server administrator.' ),
-						'5.5.3'
-					)
-				);
-			} else {
-				$result['description'] .= sprintf(
-					'<p>%s</p>',
-					__( 'Your MySQL version supports utf8mb4.' )
-				);
-			}
-		} else { // MariaDB introduced utf8mb4 support in 5.5.0.
-			if ( version_compare( $this->mysql_server_version, '5.5.0', '<' ) ) {
-				$result['status'] = 'recommended';
-
-				$result['label'] = __( 'utf8mb4 requires a MariaDB update' );
-
-				$result['description'] .= sprintf(
-					'<p>%s</p>',
-					sprintf(
-						/* translators: %s: Version number. */
-						__( 'WordPress&#8217; utf8mb4 support requires MariaDB version %s or greater. Please contact your server administrator.' ),
-						'5.5.0'
-					)
-				);
-			} else {
-				$result['description'] .= sprintf(
-					'<p>%s</p>',
-					__( 'Your MariaDB version supports utf8mb4.' )
-				);
-			}
-		}
-
-		// phpcs:ignore WordPress.DB.RestrictedFunctions.mysql_mysqli_get_client_info
-		$mysql_client_version = mysqli_get_client_info();
-
-		/*
-		 * libmysql has supported utf8mb4 since 5.5.3, same as the MySQL server.
-		 * mysqlnd has supported utf8mb4 since 5.0.9.
-		 */
-		if ( str_contains( $mysql_client_version, 'mysqlnd' ) ) {
-			$mysql_client_version = preg_replace( '/^\D+([\d.]+).*/', '$1', $mysql_client_version );
-			if ( version_compare( $mysql_client_version, '5.0.9', '<' ) ) {
-				$result['status'] = 'recommended';
-
-				$result['label'] = __( 'utf8mb4 requires a newer client library' );
-
-				$result['description'] .= sprintf(
-					'<p>%s</p>',
-					sprintf(
-						/* translators: 1: Name of the library, 2: Number of version. */
-						__( 'WordPress&#8217; utf8mb4 support requires MySQL client library (%1$s) version %2$s or newer. Please contact your server administrator.' ),
-						'mysqlnd',
-						'5.0.9'
-					)
-				);
-			}
-		} else {
-			if ( version_compare( $mysql_client_version, '5.5.3', '<' ) ) {
-				$result['status'] = 'recommended';
-
-				$result['label'] = __( 'utf8mb4 requires a newer client library' );
-
-				$result['description'] .= sprintf(
-					'<p>%s</p>',
-					sprintf(
-						/* translators: 1: Name of the library, 2: Number of version. */
-						__( 'WordPress&#8217; utf8mb4 support requires MySQL client library (%1$s) version %2$s or newer. Please contact your server administrator.' ),
-						'libmysql',
-						'5.5.3'
-					)
-				);
-			}
-		}
-
-		return $result;
-	}
-
 	/**
 	 * Tests if the site can communicate with WordPress.org.
 	 *
@@ -2739,10 +2625,6 @@ class WP_Site_Health {
 					'label' => __( 'Database Server version' ),
 					'test'  => 'sql_server',
 				),
-				'utf8mb4_support'              => array(
-					'label' => __( 'MySQL utf8mb4 support' ),
-					'test'  => 'utf8mb4_support',
-				),
 				'ssl_support'                  => array(
 					'label' => __( 'Secure communication' ),
 					'test'  => 'ssl_support',

wp-admin/setup-config.php

@@ -396,7 +396,7 @@ switch ( $step ) {
 					$config_file[ $line_num ] = "define( '" . $constant . "'," . $padding . "'" . addcslashes( constant( $constant ), "\\'" ) . "' );\r\n";
 					break;
 				case 'DB_CHARSET':
-					if ( 'utf8mb4' === $wpdb->charset || ( ! $wpdb->charset && $wpdb->has_cap( 'utf8mb4' ) ) ) {
+					if ( 'utf8mb4' === $wpdb->charset || ( ! $wpdb->charset ) ) {
 						$config_file[ $line_num ] = "define( '" . $constant . "'," . $padding . "'utf8mb4' );\r\n";
 					}
 					break;

wp-includes/class-wpdb.php

@@ -878,15 +878,10 @@ class wpdb {
 			return compact( 'charset', 'collate' );
 		}
 
-		if ( 'utf8' === $charset && $this->has_cap( 'utf8mb4' ) ) {
+		if ( 'utf8' === $charset ) {
 			$charset = 'utf8mb4';
 		}
 
-		if ( 'utf8mb4' === $charset && ! $this->has_cap( 'utf8mb4' ) ) {
-			$charset = 'utf8';
-			$collate = str_replace( 'utf8mb4_', 'utf8_', $collate );
-		}
-
 		if ( 'utf8mb4' === $charset ) {
 			// _general_ is outdated, so we can upgrade it to _unicode_, instead.
 			if ( ! $collate || 'utf8_general_ci' === $collate ) {
@@ -3242,11 +3237,6 @@ class wpdb {
 			if ( ! empty( $column->Collation ) ) {
 				list( $charset ) = explode( '_', $column->Collation );
 
-				// If the current connection can't support utf8mb4 characters, let's only send 3-byte utf8 characters.
-				if ( 'utf8mb4' === $charset && ! $this->has_cap( 'utf8mb4' ) ) {
-					$charset = 'utf8';
-				}
-
 				$charsets[ strtolower( $charset ) ] = true;
 			}
 
@@ -4057,6 +4047,7 @@ class wpdb {
 	 * @since 4.1.0 Added support for the 'utf8mb4' feature.
 	 * @since 4.6.0 Added support for the 'utf8mb4_520' feature.
 	 * @since 6.2.0 Added support for the 'identifier_placeholders' feature.
+	 * @since 6.6.0 The `utf8mb4` feature now always returns true.
 	 *
 	 * @see wpdb::db_version()
 	 *
@@ -4092,26 +4083,7 @@ class wpdb {
 			case 'set_charset':
 				return version_compare( $db_version, '5.0.7', '>=' );
 			case 'utf8mb4':      // @since 4.1.0
-				if ( version_compare( $db_version, '5.5.3', '<' ) ) {
+				return true;
-					return false;
-				}
-
-				$client_version = mysqli_get_client_info();
-
-				/*
-				 * libmysql has supported utf8mb4 since 5.5.3, same as the MySQL server.
-				 * mysqlnd has supported utf8mb4 since 5.0.9.
-				 *
-				 * Note: str_contains() is not used here, as this file can be included
-				 * directly outside of WordPress core, e.g. by HyperDB, in which case
-				 * the polyfills from wp-includes/compat.php are not loaded.
-				 */
-				if ( false !== strpos( $client_version, 'mysqlnd' ) ) {
-					$client_version = preg_replace( '/^\D+([\d.]+).*/', '$1', $client_version );
-					return version_compare( $client_version, '5.0.9', '>=' );
-				} else {
-					return version_compare( $client_version, '5.5.3', '>=' );
-				}
 			case 'utf8mb4_520': // @since 4.6.0
 				return version_compare( $db_version, '5.6', '>=' );
 			case 'identifier_placeholders': // @since 6.2.0

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.6-alpha-57925';
+$wp_version = '6.6-alpha-57926';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.