2018年12月7日にリリースされたWordPress 5.0に早速バージョンアップしました。なぜか管理画面のエディタの一部が翻訳されないという現象が発生中。

試したこと

どれもだめなので現在は対処案を模索中。どうしたもんか…。

  • wp-instant-setup-jpを使ってローカル環境でのテスト
  • AWS上にあるKUSANAGIを使ってのテスト
  • ブラウザのキャッシュクリア
  • 翻訳ファイルを個別にDLして置換

追記 : 2018-12-07 14:08
すでにWordSlackでは問題がある人とそうでない人がいることが判明。

https://wpja.slack.com/archives/C02T7MR4C/p1544187659013300?thread_ts=1544166154.007600&cid=C02T7MR4C

Gutenbergをインストールした状態でアップデートした場合に限り、翻訳が適用されるという状態らいしい。
なので、来週にはWordPress 5.0.1? がリリースする予定とのことで、その頃にはGutenberg周りの問題も落ち着くのではないでしょうか。


更に進展しまして、Gutenbergをインストールした状態でアップデートをするとlanguagesディレクトリにいくつかのJSONファイルが生成されてそれがある場合は正常に翻訳がされるようです。

「え。もう更新しちゃったよ。お客さんになんて説明すんねん!」って人は記事の最後に添付してあるzipファイルを展開して中身をlanguagesに置くと翻訳が適用されます!
見ず知らずの人から渡された謎のファイルを本番環境にアップするのはとっても怖いと思いますしとっても危険なので自己責任でお願いします!


追記 2018-12-09 10:59

さらにWordSlackにて進展があったので箇条書きで追記します。

  • イタリア語でも同様の問題が発生しておりパッチもすでに出ているので近い内に改善しそう
  • jsonファイルをアップしただけでは適用されない環境もある

とのことでした。該当のイシューのURLはこちら。
45528.2.patch on Ticket #45528 – Attachment – WordPress Trac

wp-includes/l10n.php を下記のように修正し、前述のjsonをアップすると大抵は改善すると思います。

[code lang=”php”] <?php /** * Core Translation API * * @package WordPress * @subpackage i18n * @since 1.2.0 */ /** * Retrieves the current locale. * * If the locale is set, then it will filter the locale in the {@see ‘locale’} * filter hook and return the value. * * If the locale is not set already, then the WPLANG constant is used if it is * defined. Then it is filtered through the {@see ‘locale’} filter hook and * the value for the locale global set and the locale is returned. * * The process to get the locale should only be done once, but the locale will * always be filtered using the {@see ‘locale’} hook. * * @since 1.5.0 * * @global string $locale * @global string $wp_local_package * * @return string The locale of the blog or from the {@see ‘locale’} hook. */ function get_locale() { global $locale, $wp_local_package; if ( isset( $locale ) ) { /** * Filters the locale ID of the WordPress installation. * * @since 1.5.0 * * @param string $locale The locale ID. */ return apply_filters( ‘locale’, $locale ); } if ( isset( $wp_local_package ) ) { $locale = $wp_local_package; } // WPLANG was defined in wp-config. if ( defined( ‘WPLANG’ ) ) { $locale = WPLANG; } // If multisite, check options. if ( is_multisite() ) { // Don’t check blog option when installing. if ( wp_installing() || ( false === $ms_locale = get_option( ‘WPLANG’ ) ) ) { $ms_locale = get_site_option( ‘WPLANG’ ); } if ( $ms_locale !== false ) { $locale = $ms_locale; } } else { $db_locale = get_option( ‘WPLANG’ ); if ( $db_locale !== false ) { $locale = $db_locale; } } if ( empty( $locale ) ) { $locale = ‘en_US’; } /** This filter is documented in wp-includes/l10n.php */ return apply_filters( ‘locale’, $locale ); } /** * Retrieves the locale of a user. * * If the user has a locale set to a non-empty string then it will be * returned. Otherwise it returns the locale of get_locale(). * * @since 4.7.0 * * @param int|WP_User $user_id User’s ID or a WP_User object. Defaults to current user. * @return string The locale of the user. */ function get_user_locale( $user_id = 0 ) { $user = false; if ( 0 === $user_id &amp;amp;amp;amp;&amp;amp;amp;amp; function_exists( ‘wp_get_current_user’ ) ) { $user = wp_get_current_user(); } elseif ( $user_id instanceof WP_User ) { $user = $user_id; } elseif ( $user_id &amp;amp;amp;amp;&amp;amp;amp;amp; is_numeric( $user_id ) ) { $user = get_user_by( ‘id’, $user_id ); } if ( ! $user ) { return get_locale(); } $locale = $user-&amp;amp;gt;locale; return $locale ? $locale : get_locale(); } /** * Determine the current locale desired for the request. * * @since 5.0.0 * * @global string $pagenow * * @return string The determined locale. */ function determine_locale() { /** * Filters the locale for the current request prior to the default determination process. * * Using this filter allows to override the default logic, effectively short-circuiting the function. * * @since 5.0.0 * * @param string|null The locale to return and short-circuit, or null as default. */ $determined_locale = apply_filters( ‘pre_determine_locale’, null ); if ( ! empty( $determined_locale ) &amp;amp;amp;amp;&amp;amp;amp;amp; is_string( $determined_locale ) ) { return $determined_locale; } $determined_locale = get_locale(); if ( is_admin() ) { $determined_locale = get_user_locale(); } if ( isset( $_GET[‘_locale’] ) &amp;amp;amp;amp;&amp;amp;amp;amp; ‘user’ === $_GET[‘_locale’] &amp;amp;amp;amp;&amp;amp;amp;amp; wp_is_json_request() ) { $determined_locale = get_user_locale(); } if ( ! empty( $_GET[‘wp_lang’] ) &amp;amp;amp;amp;&amp;amp;amp;amp; ‘wp-login.php’ === $GLOBALS[‘pagenow’] ) { $determined_locale = sanitize_text_field( $_GET[‘wp_lang’] ); } /** * Filters the locale for the current request. * * @since 5.0.0 * * @param string $locale The locale. */ return apply_filters( ‘determine_locale’, $determined_locale ); } /** * Retrieve the translation of $text. * * If there is no translation, or the text domain isn’t loaded, the original text is returned. * * *Note:* Don’t use translate() directly, use __() or related functions. * * @since 2.2.0 * * @param string $text Text to translate. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated text */ function translate( $text, $domain = ‘default’ ) { $translations = get_translations_for_domain( $domain ); $translation = $translations-&amp;amp;gt;translate( $text ); /** * Filters text with its translation. * * @since 2.0.11 * * @param string $translation Translated text. * @param string $text Text to translate. * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ return apply_filters( ‘gettext’, $translation, $text, $domain ); } /** * Remove last item on a pipe-delimited string. * * Meant for removing the last item in a string, such as ‘Role name|User role’. The original * string will be returned if no pipe ‘|’ characters are found in the string. * * @since 2.8.0 * * @param string $string A pipe-delimited string. * @return string Either $string or everything before the last pipe. */ function before_last_bar( $string ) { $last_bar = strrpos( $string, ‘|’ ); if ( false === $last_bar ) { return $string; } else { return substr( $string, 0, $last_bar ); } } /** * Retrieve the translation of $text in the context defined in $context. * * If there is no translation, or the text domain isn’t loaded the original * text is returned. * * *Note:* Don’t use translate_with_gettext_context() directly, use _x() or related functions. * * @since 2.8.0 * * @param string $text Text to translate. * @param string $context Context information for the translators. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated text on success, original text on failure. */ function translate_with_gettext_context( $text, $context, $domain = ‘default’ ) { $translations = get_translations_for_domain( $domain ); $translation = $translations-&amp;amp;gt;translate( $text, $context ); /** * Filters text with its translation based on context information. * * @since 2.8.0 * * @param string $translation Translated text. * @param string $text Text to translate. * @param string $context Context information for the translators. * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ return apply_filters( ‘gettext_with_context’, $translation, $text, $context, $domain ); } /** * Retrieve the translation of $text. * * If there is no translation, or the text domain isn’t loaded, the original text is returned. * * @since 2.1.0 * * @param string $text Text to translate. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated text. */ function __( $text, $domain = ‘default’ ) { return translate( $text, $domain ); } /** * Retrieve the translation of $text and escapes it for safe use in an attribute. * * If there is no translation, or the text domain isn’t loaded, the original text is returned. * * @since 2.8.0 * * @param string $text Text to translate. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated text on success, original text on failure. */ function esc_attr__( $text, $domain = ‘default’ ) { return esc_attr( translate( $text, $domain ) ); } /** * Retrieve the translation of $text and escapes it for safe use in HTML output. * * If there is no translation, or the text domain isn’t loaded, the original text * is escaped and returned.. * * @since 2.8.0 * * @param string $text Text to translate. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated text */ function esc_html__( $text, $domain = ‘default’ ) { return esc_html( translate( $text, $domain ) ); } /** * Display translated text. * * @since 1.2.0 * * @param string $text Text to translate. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. */ function _e( $text, $domain = ‘default’ ) { echo translate( $text, $domain ); } /** * Display translated text that has been escaped for safe use in an attribute. * * @since 2.8.0 * * @param string $text Text to translate. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. */ function esc_attr_e( $text, $domain = ‘default’ ) { echo esc_attr( translate( $text, $domain ) ); } /** * Display translated text that has been escaped for safe use in HTML output. * * @since 2.8.0 * * @param string $text Text to translate. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. */ function esc_html_e( $text, $domain = ‘default’ ) { echo esc_html( translate( $text, $domain ) ); } /** * Retrieve translated string with gettext context. * * Quite a few times, there will be collisions with similar translatable text * found in more than two places, but with different translated context. * * By including the context in the pot file, translators can translate the two * strings differently. * * @since 2.8.0 * * @param string $text Text to translate. * @param string $context Context information for the translators. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated context string without pipe. */ function _x( $text, $context, $domain = ‘default’ ) { return translate_with_gettext_context( $text, $context, $domain ); } /** * Display translated string with gettext context. * * @since 3.0.0 * * @param string $text Text to translate. * @param string $context Context information for the translators. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated context string without pipe. */ function _ex( $text, $context, $domain = ‘default’ ) { echo _x( $text, $context, $domain ); } /** * Translate string with gettext context, and escapes it for safe use in an attribute. * * @since 2.8.0 * * @param string $text Text to translate. * @param string $context Context information for the translators. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated text */ function esc_attr_x( $text, $context, $domain = ‘default’ ) { return esc_attr( translate_with_gettext_context( $text, $context, $domain ) ); } /** * Translate string with gettext context, and escapes it for safe use in HTML output. * * @since 2.9.0 * * @param string $text Text to translate. * @param string $context Context information for the translators. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string Translated text. */ function esc_html_x( $text, $context, $domain = ‘default’ ) { return esc_html( translate_with_gettext_context( $text, $context, $domain ) ); } /** * Translates and retrieves the singular or plural form based on the supplied number. * * Used when you want to use the appropriate form of a string based on whether a * number is singular or plural. * * Example: * * printf( _n( ‘%s person’, ‘%s people’, $count, ‘text-domain’ ), number_format_i18n( $count ) ); * * @since 2.8.0 * * @param string $single The text to be used if the number is singular. * @param string $plural The text to be used if the number is plural. * @param int $number The number to compare against to use either the singular or plural form. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string The translated singular or plural form. */ function _n( $single, $plural, $number, $domain = ‘default’ ) { $translations = get_translations_for_domain( $domain ); $translation = $translations-&amp;amp;gt;translate_plural( $single, $plural, $number ); /** * Filters the singular or plural form of a string. * * @since 2.2.0 * * @param string $translation Translated text. * @param string $single The text to be used if the number is singular. * @param string $plural The text to be used if the number is plural. * @param string $number The number to compare against to use either the singular or plural form. * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ return apply_filters( ‘ngettext’, $translation, $single, $plural, $number, $domain ); } /** * Translates and retrieves the singular or plural form based on the supplied number, with gettext context. * * This is a hybrid of _n() and _x(). It supports context and plurals. * * Used when you want to use the appropriate form of a string with context based on whether a * number is singular or plural. * * Example of a generic phrase which is disambiguated via the context parameter: * * printf( _nx( ‘%s group’, ‘%s groups’, $people, ‘group of people’, ‘text-domain’ ), number_format_i18n( $people ) ); * printf( _nx( ‘%s group’, ‘%s groups’, $animals, ‘group of animals’, ‘text-domain’ ), number_format_i18n( $animals ) ); * * @since 2.8.0 * * @param string $single The text to be used if the number is singular. * @param string $plural The text to be used if the number is plural. * @param int $number The number to compare against to use either the singular or plural form. * @param string $context Context information for the translators. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default ‘default’. * @return string The translated singular or plural form. */ function _nx($single, $plural, $number, $context, $domain = ‘default’) { $translations = get_translations_for_domain( $domain ); $translation = $translations-&amp;amp;gt;translate_plural( $single, $plural, $number, $context ); /** * Filters the singular or plural form of a string with gettext context. * * @since 2.8.0 * * @param string $translation Translated text. * @param string $single The text to be used if the number is singular. * @param string $plural The text to be used if the number is plural. * @param string $number The number to compare against to use either the singular or plural form. * @param string $context Context information for the translators. * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ return apply_filters( ‘ngettext_with_context’, $translation, $single, $plural, $number, $context, $domain ); } /** * Registers plural strings in POT file, but does not translate them. * * Used when you want to keep structures with translatable plural * strings and use them later when the number is known. * * Example: * * $message = _n_noop( ‘%s post’, ‘%s posts’, ‘text-domain’ ); * … * printf( translate_nooped_plural( $message, $count, ‘text-domain’ ), number_format_i18n( $count ) ); * * @since 2.5.0 * * @param string $singular Singular form to be localized. * @param string $plural Plural form to be localized. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default null. * @return array { * Array of translation information for the strings. * * @type string $0 Singular form to be localized. No longer used. * @type string $1 Plural form to be localized. No longer used. * @type string $singular Singular form to be localized. * @type string $plural Plural form to be localized. * @type null $context Context information for the translators. * @type string $domain Text domain. * } */ function _n_noop( $singular, $plural, $domain = null ) { return array( 0 =&amp;amp;gt; $singular, 1 =&amp;amp;gt; $plural, ‘singular’ =&amp;amp;gt; $singular, ‘plural’ =&amp;amp;gt; $plural, ‘context’ =&amp;amp;gt; null, ‘domain’ =&amp;amp;gt; $domain ); } /** * Registers plural strings with gettext context in POT file, but does not translate them. * * Used when you want to keep structures with translatable plural * strings and use them later when the number is known. * * Example of a generic phrase which is disambiguated via the context parameter: * * $messages = array( * ‘people’ =&amp;amp;gt; _nx_noop( ‘%s group’, ‘%s groups’, ‘people’, ‘text-domain’ ), * ‘animals’ =&amp;amp;gt; _nx_noop( ‘%s group’, ‘%s groups’, ‘animals’, ‘text-domain’ ), * ); * … * $message = $messages[ $type ]; * printf( translate_nooped_plural( $message, $count, ‘text-domain’ ), number_format_i18n( $count ) ); * * @since 2.8.0 * * @param string $singular Singular form to be localized. * @param string $plural Plural form to be localized. * @param string $context Context information for the translators. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. * Default null. * @return array { * Array of translation information for the strings. * * @type string $0 Singular form to be localized. No longer used. * @type string $1 Plural form to be localized. No longer used. * @type string $2 Context information for the translators. No longer used. * @type string $singular Singular form to be localized. * @type string $plural Plural form to be localized. * @type string $context Context information for the translators. * @type string $domain Text domain. * } */ function _nx_noop( $singular, $plural, $context, $domain = null ) { return array( 0 =&amp;amp;gt; $singular, 1 =&amp;amp;gt; $plural, 2 =&amp;amp;gt; $context, ‘singular’ =&amp;amp;gt; $singular, ‘plural’ =&amp;amp;gt; $plural, ‘context’ =&amp;amp;gt; $context, ‘domain’ =&amp;amp;gt; $domain ); } /** * Translates and retrieves the singular or plural form of a string that’s been registered * with _n_noop() or _nx_noop(). * * Used when you want to use a translatable plural string once the number is known. * * Example: * * $message = _n_noop( ‘%s post’, ‘%s posts’, ‘text-domain’ ); * … * printf( translate_nooped_plural( $message, $count, ‘text-domain’ ), number_format_i18n( $count ) ); * * @since 3.1.0 * * @param array $nooped_plural Array with singular, plural, and context keys, usually the result of _n_noop() or _nx_noop(). * @param int $count Number of objects. * @param string $domain Optional. Text domain. Unique identifier for retrieving translated strings. If $nooped_plural contains * a text domain passed to _n_noop() or _nx_noop(), it will override this value. Default ‘default’. * @return string Either $single or $plural translated text. */ function translate_nooped_plural( $nooped_plural, $count, $domain = ‘default’ ) { if ( $nooped_plural[‘domain’] ) $domain = $nooped_plural[‘domain’]; if ( $nooped_plural[‘context’] ) return _nx( $nooped_plural[‘singular’], $nooped_plural[‘plural’], $count, $nooped_plural[‘context’], $domain ); else return _n( $nooped_plural[‘singular’], $nooped_plural[‘plural’], $count, $domain ); } /** * Load a .mo file into the text domain $domain. * * If the text domain already exists, the translations will be merged. If both * sets have the same string, the translation from the original value will be taken. * * On success, the .mo file will be placed in the $l10n global by $domain * and will be a MO object. * * @since 1.5.0 * * @global array $l10n An array of all currently loaded text domains. * @global array $l10n_unloaded An array of all text domains that have been unloaded again. * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @param string $mofile Path to the .mo file. * @return bool True on success, false on failure. */ function load_textdomain( $domain, $mofile ) { global $l10n, $l10n_unloaded; $l10n_unloaded = (array) $l10n_unloaded; /** * Filters whether to override the .mo file loading. * * @since 2.9.0 * * @param bool $override Whether to override the .mo file loading. Default false. * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @param string $mofile Path to the MO file. */ $plugin_override = apply_filters( ‘override_load_textdomain’, false, $domain, $mofile ); if ( true == $plugin_override ) { unset( $l10n_unloaded[ $domain ] ); return true; } /** * Fires before the MO translation file is loaded. * * @since 2.9.0 * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @param string $mofile Path to the .mo file. */ do_action( ‘load_textdomain’, $domain, $mofile ); /** * Filters MO file path for loading translations for a specific text domain. * * @since 2.9.0 * * @param string $mofile Path to the MO file. * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ $mofile = apply_filters( ‘load_textdomain_mofile’, $mofile, $domain ); if ( !is_readable( $mofile ) ) return false; $mo = new MO(); if ( !$mo-&amp;amp;gt;import_from_file( $mofile ) ) return false; if ( isset( $l10n[$domain] ) ) $mo-&amp;amp;gt;merge_with( $l10n[$domain] ); unset( $l10n_unloaded[ $domain ] ); $l10n[$domain] = &amp;amp;amp;amp;$mo; return true; } /** * Unload translations for a text domain. * * @since 3.0.0 * * @global array $l10n An array of all currently loaded text domains. * @global array $l10n_unloaded An array of all text domains that have been unloaded again. * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @return bool Whether textdomain was unloaded. */ function unload_textdomain( $domain ) { global $l10n, $l10n_unloaded; $l10n_unloaded = (array) $l10n_unloaded; /** * Filters whether to override the text domain unloading. * * @since 3.0.0 * * @param bool $override Whether to override the text domain unloading. Default false. * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ $plugin_override = apply_filters( ‘override_unload_textdomain’, false, $domain ); if ( $plugin_override ) { $l10n_unloaded[ $domain ] = true; return true; } /** * Fires before the text domain is unloaded. * * @since 3.0.0 * * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ do_action( ‘unload_textdomain’, $domain ); if ( isset( $l10n[$domain] ) ) { unset( $l10n[$domain] ); $l10n_unloaded[ $domain ] = true; return true; } return false; } /** * Load default translated strings based on locale. * * Loads the .mo file in WP_LANG_DIR constant path from WordPress root. * The translated (.mo) file is named based on the locale. * * @see load_textdomain() * * @since 1.5.0 * * @param string $locale Optional. Locale to load. Default is the value of get_locale(). * @return bool Whether the textdomain was loaded. */ function load_default_textdomain( $locale = null ) { if ( null === $locale ) { $locale = determine_locale(); } // Unload previously loaded strings so we can switch translations. unload_textdomain( ‘default’ ); $return = load_textdomain( ‘default’, WP_LANG_DIR . &amp;amp;quot;/$locale.mo&amp;amp;quot; ); if ( ( is_multisite() || ( defined( ‘WP_INSTALLING_NETWORK’ ) &amp;amp;amp;amp;&amp;amp;amp;amp; WP_INSTALLING_NETWORK ) ) &amp;amp;amp;amp;&amp;amp;amp;amp; ! file_exists( WP_LANG_DIR . &amp;amp;quot;/admin-$locale.mo&amp;amp;quot; ) ) { load_textdomain( ‘default’, WP_LANG_DIR . &amp;amp;quot;/ms-$locale.mo&amp;amp;quot; ); return $return; } if ( is_admin() || wp_installing() || ( defined( ‘WP_REPAIRING’ ) &amp;amp;amp;amp;&amp;amp;amp;amp; WP_REPAIRING ) ) { load_textdomain( ‘default’, WP_LANG_DIR . &amp;amp;quot;/admin-$locale.mo&amp;amp;quot; ); } if ( is_network_admin() || ( defined( ‘WP_INSTALLING_NETWORK’ ) &amp;amp;amp;amp;&amp;amp;amp;amp; WP_INSTALLING_NETWORK ) ) load_textdomain( ‘default’, WP_LANG_DIR . &amp;amp;quot;/admin-network-$locale.mo&amp;amp;quot; ); return $return; } /** * Loads a plugin’s translated strings. * * If the path is not given then it will be the root of the plugin directory. * * The .mo file should be named based on the text domain with a dash, and then the locale exactly. * * @since 1.5.0 * @since 4.6.0 The function now tries to load the .mo file from the languages directory first. * * @param string $domain Unique identifier for retrieving translated strings * @param string $deprecated Optional. Use the $plugin_rel_path parameter instead. Default false. * @param string $plugin_rel_path Optional. Relative path to WP_PLUGIN_DIR where the .mo file resides. * Default false. * @return bool True when textdomain is successfully loaded, false otherwise. */ function load_plugin_textdomain( $domain, $deprecated = false, $plugin_rel_path = false ) { /** * Filters a plugin’s locale. * * @since 3.0.0 * * @param string $locale The plugin’s current locale. * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ $locale = apply_filters( ‘plugin_locale’, determine_locale(), $domain ); $mofile = $domain . ‘-‘ . $locale . ‘.mo’; // Try to load from the languages directory first. if ( load_textdomain( $domain, WP_LANG_DIR . ‘/plugins/’ . $mofile ) ) { return true; } if ( false !== $plugin_rel_path ) { $path = WP_PLUGIN_DIR . ‘/’ . trim( $plugin_rel_path, ‘/’ ); } elseif ( false !== $deprecated ) { _deprecated_argument( __FUNCTION__, ‘2.7.0’ ); $path = ABSPATH . trim( $deprecated, ‘/’ ); } else { $path = WP_PLUGIN_DIR; } return load_textdomain( $domain, $path . ‘/’ . $mofile ); } /** * Load the translated strings for a plugin residing in the mu-plugins directory. * * @since 3.0.0 * @since 4.6.0 The function now tries to load the .mo file from the languages directory first. * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @param string $mu_plugin_rel_path Optional. Relative to `WPMU_PLUGIN_DIR` directory in which the .mo * file resides. Default empty string. * @return bool True when textdomain is successfully loaded, false otherwise. */ function load_muplugin_textdomain( $domain, $mu_plugin_rel_path = ” ) { /** This filter is documented in wp-includes/l10n.php */ $locale = apply_filters( ‘plugin_locale’, determine_locale(), $domain ); $mofile = $domain . ‘-‘ . $locale . ‘.mo’; // Try to load from the languages directory first. if ( load_textdomain( $domain, WP_LANG_DIR . ‘/plugins/’ . $mofile ) ) { return true; } $path = WPMU_PLUGIN_DIR . ‘/’ . ltrim( $mu_plugin_rel_path, ‘/’ ); return load_textdomain( $domain, $path . ‘/’ . $mofile ); } /** * Load the theme’s translated strings. * * If the current locale exists as a .mo file in the theme’s root directory, it * will be included in the translated strings by the $domain. * * The .mo files must be named based on the locale exactly. * * @since 1.5.0 * @since 4.6.0 The function now tries to load the .mo file from the languages directory first. * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @param string $path Optional. Path to the directory containing the .mo file. * Default false. * @return bool True when textdomain is successfully loaded, false otherwise. */ function load_theme_textdomain( $domain, $path = false ) { /** * Filters a theme’s locale. * * @since 3.0.0 * * @param string $locale The theme’s current locale. * @param string $domain Text domain. Unique identifier for retrieving translated strings. */ $locale = apply_filters( ‘theme_locale’, determine_locale(), $domain ); $mofile = $domain . ‘-‘ . $locale . ‘.mo’; // Try to load from the languages directory first. if ( load_textdomain( $domain, WP_LANG_DIR . ‘/themes/’ . $mofile ) ) { return true; } if ( ! $path ) { $path = get_template_directory(); } return load_textdomain( $domain, $path . ‘/’ . $locale . ‘.mo’ ); } /** * Load the child themes translated strings. * * If the current locale exists as a .mo file in the child themes * root directory, it will be included in the translated strings by the $domain. * * The .mo files must be named based on the locale exactly. * * @since 2.9.0 * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @param string $path Optional. Path to the directory containing the .mo file. * Default false. * @return bool True when the theme textdomain is successfully loaded, false otherwise. */ function load_child_theme_textdomain( $domain, $path = false ) { if ( ! $path ) $path = get_stylesheet_directory(); return load_theme_textdomain( $domain, $path ); } /** * Load the script translated strings. * * @see WP_Scripts::set_translations() * @link https://core.trac.wordpress.org/ticket/45103 * @global WP_Scripts $wp_scripts The WP_Scripts object for printing scripts. * * @since 5.0.0 * * @param string $handle Name of the script to register a translation domain to. * @param string $domain The textdomain. * @param string $path Optional. The full file path to the directory containing translation files. * * @return false|string False if the script textdomain could not be loaded, the translated strings * in JSON encoding otherwise. */ function load_script_textdomain( $handle, $domain, $path = null ) { global $wp_scripts; $path = untrailingslashit( $path ); $locale = determine_locale(); // If a path was given and the handle file exists simply return it. $file_base = $domain === ‘default’ ? $locale : $domain . ‘-‘ . $locale; $handle_filename = $file_base . ‘-‘ . $handle . ‘.json’; if ( $path &amp;amp;amp;amp;&amp;amp;amp;amp; file_exists( $path . ‘/’ . $handle_filename ) ) { return file_get_contents( $path . ‘/’ . $handle_filename ); } $obj = $wp_scripts-&amp;amp;gt;registered[ $handle ]; $src = $obj-&amp;amp;gt;src; if ( ! preg_match( ‘|^(https?:)?//|’, $src ) &amp;amp;amp;amp;&amp;amp;amp;amp; ! ( $wp_scripts-&amp;amp;gt;content_url &amp;amp;amp;amp;&amp;amp;amp;amp; 0 === strpos( $src, $wp_scripts-&amp;amp;gt;content_url ) ) ) { $src = $wp_scripts-&amp;amp;gt;base_url . $src; } /** This filter is documented in wp-includes/class.wp-scripts.php */ $src = esc_url( apply_filters( ‘script_loader_src’, $src, $handle ) ); $relative = false; $languages_path = WP_LANG_DIR; $src_url = wp_parse_url( $src ); $content_url = wp_parse_url( content_url() ); $site_url = wp_parse_url( site_url() ); // If the host is the same or it’s a relative URL. if ( strpos( $src_url[‘path’], $content_url[‘path’] ) === 0 &amp;amp;amp;amp;&amp;amp;amp;amp; ( ! isset( $src_url[‘host’] ) || $src_url[‘host’] === $content_url[‘host’] ) ) { // Make the src relative the specific plugin or theme. $relative = trim( substr( $src_url[‘path’], strlen( $content_url[‘path’] ) ), ‘/’ ); $relative = explode( ‘/’, $relative ); $languages_path = WP_LANG_DIR . ‘/’ . $relative[0]; $relative = array_slice( $relative, 2 ); $relative = implode( ‘/’, $relative ); } elseif ( ! isset( $src_url[‘host’] ) || $src_url[‘host’] === $site_url[‘host’] ) { if ( ! isset( $site_url[‘path’] ) ) { $relative = trim( $src_url[‘path’], ‘/’ ); } elseif ( ( strpos( $src_url[‘path’], trailingslashit( $site_url[‘path’] ) ) === 0 ) ) { // Make the src relative to the WP root. $relative = substr( $src_url[‘path’], strlen( $site_url[‘path’] ) ); $relative = trim( $relative, ‘/’ ); } } // If the source is not from WP. if ( false === $relative ) { return false; } // Translations are always based on the unminified filename. if ( substr( $relative, -7 ) === ‘.min.js’ ) { $relative = substr( $relative, 0, -7 ) . ‘.js’; } $md5_filename = $file_base . ‘-‘ . md5( $relative ) . ‘.json’; if ( $path &amp;amp;amp;amp;&amp;amp;amp;amp; file_exists( $path . ‘/’ . $md5_filename ) ) { return file_get_contents( $path . ‘/’ . $md5_filename ); } if ( file_exists( $languages_path . ‘/’ . $md5_filename ) ) { return file_get_contents( $languages_path . ‘/’ . $md5_filename ); } return false; } /** * Loads plugin and theme textdomains just-in-time. * * When a textdomain is encountered for the first time, we try to load * the translation file from `wp-content/languages`, removing the need * to call load_plugin_texdomain() or load_theme_texdomain(). * * @since 4.6.0 * @access private * * @see get_translations_for_domain() * @global array $l10n_unloaded An array of all text domains that have been unloaded again. * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @return bool True when the textdomain is successfully loaded, false otherwise. */ function _load_textdomain_just_in_time( $domain ) { global $l10n_unloaded; $l10n_unloaded = (array) $l10n_unloaded; // Short-circuit if domain is ‘default’ which is reserved for core. if ( ‘default’ === $domain || isset( $l10n_unloaded[ $domain ] ) ) { return false; } $translation_path = _get_path_to_translation( $domain ); if ( false === $translation_path ) { return false; } return load_textdomain( $domain, $translation_path ); } /** * Gets the path to a translation file for loading a textdomain just in time. * * Caches the retrieved results internally. * * @since 4.7.0 * @access private * * @see _load_textdomain_just_in_time() * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @param bool $reset Whether to reset the internal cache. Used by the switch to locale functionality. * @return string|false The path to the translation file or false if no translation file was found. */ function _get_path_to_translation( $domain, $reset = false ) { static $available_translations = array(); if ( true === $reset ) { $available_translations = array(); } if ( ! isset( $available_translations[ $domain ] ) ) { $available_translations[ $domain ] = _get_path_to_translation_from_lang_dir( $domain ); } return $available_translations[ $domain ]; } /** * Gets the path to a translation file in the languages directory for the current locale. * * Holds a cached list of available .mo files to improve performance. * * @since 4.7.0 * @access private * * @see _get_path_to_translation() * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @return string|false The path to the translation file or false if no translation file was found. */ function _get_path_to_translation_from_lang_dir( $domain ) { static $cached_mofiles = null; if ( null === $cached_mofiles ) { $cached_mofiles = array(); $locations = array( WP_LANG_DIR . ‘/plugins’, WP_LANG_DIR . ‘/themes’, ); foreach ( $locations as $location ) { $mofiles = glob( $location . ‘/*.mo’ ); if ( $mofiles ) { $cached_mofiles = array_merge( $cached_mofiles, $mofiles ); } } } $locale = determine_locale(); $mofile = &amp;amp;quot;{$domain}-{$locale}.mo&amp;amp;quot;; $path = WP_LANG_DIR . ‘/plugins/’ . $mofile; if ( in_array( $path, $cached_mofiles ) ) { return $path; } $path = WP_LANG_DIR . ‘/themes/’ . $mofile; if ( in_array( $path, $cached_mofiles ) ) { return $path; } return false; } /** * Return the Translations instance for a text domain. * * If there isn’t one, returns empty Translations instance. * * @since 2.8.0 * * @global array $l10n * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @return Translations|NOOP_Translations A Translations instance. */ function get_translations_for_domain( $domain ) { global $l10n; if ( isset( $l10n[ $domain ] ) || ( _load_textdomain_just_in_time( $domain ) &amp;amp;amp;amp;&amp;amp;amp;amp; isset( $l10n[ $domain ] ) ) ) { return $l10n[ $domain ]; } static $noop_translations = null; if ( null === $noop_translations ) { $noop_translations = new NOOP_Translations; } return $noop_translations; } /** * Whether there are translations for the text domain. * * @since 3.0.0 * * @global array $l10n * * @param string $domain Text domain. Unique identifier for retrieving translated strings. * @return bool Whether there are translations. */ function is_textdomain_loaded( $domain ) { global $l10n; return isset( $l10n[ $domain ] ); } /** * Translates role name. * * Since the role names are in the database and not in the source there * are dummy gettext calls to get them into the POT file and this function * properly translates them back. * * The before_last_bar() call is needed, because older installations keep the roles * using the old context format: ‘Role name|User role’ and just skipping the * content after the last bar is easier than fixing them in the DB. New installations * won’t suffer from that problem. * * @since 2.8.0 * * @param string $name The role name. * @return string Translated role name on success, original name on failure. */ function translate_user_role( $name ) { return translate_with_gettext_context( before_last_bar($name), ‘User role’ ); } /** * Get all available languages based on the presence of *.mo files in a given directory. * * The default directory is WP_LANG_DIR. * * @since 3.0.0 * @since 4.7.0 The results are now filterable with the {@see ‘get_available_languages’} filter. * * @param string $dir A directory to search for language files. * Default WP_LANG_DIR. * @return array An array of language codes or an empty array if no languages are present. Language codes are formed by stripping the .mo extension from the language file names. */ function get_available_languages( $dir = null ) { $languages = array(); $lang_files = glob( ( is_null( $dir ) ? WP_LANG_DIR : $dir ) . ‘/*.mo’ ); if ( $lang_files ) { foreach ( $lang_files as $lang_file ) { $lang_file = basename( $lang_file, ‘.mo’ ); if ( 0 !== strpos( $lang_file, ‘continents-cities’ ) &amp;amp;amp;amp;&amp;amp;amp;amp; 0 !== strpos( $lang_file, ‘ms-‘ ) &amp;amp;amp;amp;&amp;amp;amp;amp; 0 !== strpos( $lang_file, ‘admin-‘ ) ) { $languages[] = $lang_file; } } } /** * Filters the list of available language codes. * * @since 4.7.0 * * @param array $languages An array of available language codes. * @param string $dir The directory where the language files were found. */ return apply_filters( ‘get_available_languages’, $languages, $dir ); } /** * Get installed translations. * * Looks in the wp-content/languages directory for translations of * plugins or themes. * * @since 3.7.0 * * @param string $type What to search for. Accepts ‘plugins’, ‘themes’, ‘core’. * @return array Array of language data. */ function wp_get_installed_translations( $type ) { if ( $type !== ‘themes’ &amp;amp;amp;amp;&amp;amp;amp;amp; $type !== ‘plugins’ &amp;amp;amp;amp;&amp;amp;amp;amp; $type !== ‘core’ ) return array(); $dir = ‘core’ === $type ? ” : &amp;amp;quot;/$type&amp;amp;quot;; if ( ! is_dir( WP_LANG_DIR ) ) return array(); if ( $dir &amp;amp;amp;amp;&amp;amp;amp;amp; ! is_dir( WP_LANG_DIR . $dir ) ) return array(); $files = scandir( WP_LANG_DIR . $dir ); if ( ! $files ) return array(); $language_data = array(); foreach ( $files as $file ) { if ( ‘.’ === $file[0] || is_dir( WP_LANG_DIR . &amp;amp;quot;$dir/$file&amp;amp;quot; ) ) { continue; } if ( substr( $file, -3 ) !== ‘.po’ ) { continue; } if ( ! preg_match( ‘/(?:(.+)-)?([a-z]{2,3}(?:_[A-Z]{2})?(?:_[a-z0-9]+)?).po/’, $file, $match ) ) { continue; } if ( ! in_array( substr( $file, 0, -3 ) . ‘.mo’, $files ) ) { continue; } list( , $textdomain, $language ) = $match; if ( ” === $textdomain ) { $textdomain = ‘default’; } $language_data[ $textdomain ][ $language ] = wp_get_pomo_file_data( WP_LANG_DIR . &amp;amp;quot;$dir/$file&amp;amp;quot; ); } return $language_data; } /** * Extract headers from a PO file. * * @since 3.7.0 * * @param string $po_file Path to PO file. * @return array PO file headers. */ function wp_get_pomo_file_data( $po_file ) { $headers = get_file_data( $po_file, array( ‘POT-Creation-Date’ =&amp;amp;gt; ‘&amp;amp;quot;POT-Creation-Date’, ‘PO-Revision-Date’ =&amp;amp;gt; ‘&amp;amp;quot;PO-Revision-Date’, ‘Project-Id-Version’ =&amp;amp;gt; ‘&amp;amp;quot;Project-Id-Version’, ‘X-Generator’ =&amp;amp;gt; ‘&amp;amp;quot;X-Generator’, ) ); foreach ( $headers as $header =&amp;amp;gt; $value ) { // Remove possible contextual ‘\n’ and closing double quote. $headers[ $header ] = preg_replace( ‘~(\\\n)?&amp;amp;quot;$~’, ”, $value ); } return $headers; } /** * Language selector. * * @since 4.0.0 * @since 4.3.0 Introduced the `echo` argument. * @since 4.7.0 Introduced the `show_option_site_default` argument. * * @see get_available_languages() * @see wp_get_available_translations() * * @param string|array $args { * Optional. Array or string of arguments for outputting the language selector. * * @type string $id ID attribute of the select element. Default ‘locale’. * @type string $name Name attribute of the select element. Default ‘locale’. * @type array $languages List of installed languages, contain only the locales. * Default empty array. * @type array $translations List of available translations. Default result of * wp_get_available_translations(). * @type string $selected Language which should be selected. Default empty. * @type bool|int $echo Whether to echo the generated markup. Accepts 0, 1, or their * boolean equivalents. Default 1. * @type bool $show_available_translations Whether to show available translations. Default true. * @type bool $show_option_site_default Whether to show an option to fall back to the site’s locale. Default false. * } * @return string HTML content */ function wp_dropdown_languages( $args = array() ) { $parsed_args = wp_parse_args( $args, array( ‘id’ =&amp;amp;gt; ‘locale’, ‘name’ =&amp;amp;gt; ‘locale’, ‘languages’ =&amp;amp;gt; array(), ‘translations’ =&amp;amp;gt; array(), ‘selected’ =&amp;amp;gt; ”, ‘echo’ =&amp;amp;gt; 1, ‘show_available_translations’ =&amp;amp;gt; true, ‘show_option_site_default’ =&amp;amp;gt; false, ) ); // Bail if no ID or no name. if ( ! $parsed_args[‘id’] || ! $parsed_args[‘name’] ) { return; } // English (United States) uses an empty string for the value attribute. if ( ‘en_US’ === $parsed_args[‘selected’] ) { $parsed_args[‘selected’] = ”; } $translations = $parsed_args[‘translations’]; if ( empty( $translations ) ) { require_once( ABSPATH . ‘wp-admin/includes/translation-install.php’ ); $translations = wp_get_available_translations(); } /* * $parsed_args[‘languages’] should only contain the locales. Find the locale in * $translations to get the native name. Fall back to locale. */ $languages = array(); foreach ( $parsed_args[‘languages’] as $locale ) { if ( isset( $translations[ $locale ] ) ) { $translation = $translations[ $locale ]; $languages[] = array( ‘language’ =&amp;amp;gt; $translation[‘language’], ‘native_name’ =&amp;amp;gt; $translation[‘native_name’], ‘lang’ =&amp;amp;gt; current( $translation[‘iso’] ), ); // Remove installed language from available translations. unset( $translations[ $locale ] ); } else { $languages[] = array( ‘language’ =&amp;amp;gt; $locale, ‘native_name’ =&amp;amp;gt; $locale, ‘lang’ =&amp;amp;gt; ”, ); } } $translations_available = ( ! empty( $translations ) &amp;amp;amp;amp;&amp;amp;amp;amp; $parsed_args[‘show_available_translations’] ); // Holds the HTML markup. $structure = array(); // List installed languages. if ( $translations_available ) { $structure[] = ‘&amp;amp;amp;lt;optgroup label=&amp;amp;quot;’ . esc_attr_x( ‘Installed’, ‘translations’ ) . ‘&amp;amp;quot;&amp;amp;gt;’; } // Site default. if ( $parsed_args[‘show_option_site_default’] ) { $structure[] = sprintf( ‘&amp;amp;amp;lt;option value=&amp;amp;quot;site-default&amp;amp;quot; data-installed=&amp;amp;quot;1&amp;amp;quot;%s&amp;amp;gt;%s&amp;amp;amp;lt;/option&amp;amp;gt;’, selected( ‘site-default’, $parsed_args[‘selected’], false ), _x( ‘Site Default’, ‘default site language’ ) ); } // Always show English. $structure[] = sprintf( ‘&amp;amp;amp;lt;option value=&amp;amp;quot;&amp;amp;quot; lang=&amp;amp;quot;en&amp;amp;quot; data-installed=&amp;amp;quot;1&amp;amp;quot;%s&amp;amp;gt;English (United States)&amp;amp;amp;lt;/option&amp;amp;gt;’, selected( ”, $parsed_args[‘selected’], false ) ); // List installed languages. foreach ( $languages as $language ) { $structure[] = sprintf( ‘&amp;amp;amp;lt;option value=&amp;amp;quot;%s&amp;amp;quot; lang=&amp;amp;quot;%s&amp;amp;quot;%s data-installed=&amp;amp;quot;1&amp;amp;quot;&amp;amp;gt;%s&amp;amp;amp;lt;/option&amp;amp;gt;’, esc_attr( $language[‘language’] ), esc_attr( $language[‘lang’] ), selected( $language[‘language’], $parsed_args[‘selected’], false ), esc_html( $language[‘native_name’] ) ); } if ( $translations_available ) { $structure[] = ‘&amp;amp;amp;lt;/optgroup&amp;amp;gt;’; } // List available translations. if ( $translations_available ) { $structure[] = ‘&amp;amp;amp;lt;optgroup label=&amp;amp;quot;’ . esc_attr_x( ‘Available’, ‘translations’ ) . ‘&amp;amp;quot;&amp;amp;gt;’; foreach ( $translations as $translation ) { $structure[] = sprintf( ‘&amp;amp;amp;lt;option value=&amp;amp;quot;%s&amp;amp;quot; lang=&amp;amp;quot;%s&amp;amp;quot;%s&amp;amp;gt;%s&amp;amp;amp;lt;/option&amp;amp;gt;’, esc_attr( $translation[‘language’] ), esc_attr( current( $translation[‘iso’] ) ), selected( $translation[‘language’], $parsed_args[‘selected’], false ), esc_html( $translation[‘native_name’] ) ); } $structure[] = ‘&amp;amp;amp;lt;/optgroup&amp;amp;gt;’; } // Combine the output string. $output = sprintf( ‘&amp;amp;amp;lt;select name=&amp;amp;quot;%s&amp;amp;quot; id=&amp;amp;quot;%s&amp;amp;quot;&amp;amp;gt;’, esc_attr( $parsed_args[‘name’] ), esc_attr( $parsed_args[‘id’] ) ); $output .= join( &amp;amp;quot;\n&amp;amp;quot;, $structure ); $output .= ‘&amp;amp;amp;lt;/select&amp;amp;gt;’; if ( $parsed_args[‘echo’] ) { echo $output; } return $output; } /** * Determines whether the current locale is right-to-left (RTL). * * For more information on this and similar theme functions, check out * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/ * Conditional Tags} article in the Theme Developer Handbook. * * @since 3.0.0 * * @global WP_Locale $wp_locale * * @return bool Whether locale is RTL. */ function is_rtl() { global $wp_locale; if ( ! ( $wp_locale instanceof WP_Locale ) ) { return false; } return $wp_locale-&amp;amp;gt;is_rtl(); } /** * Switches the translations according to the given locale. * * @since 4.7.0 * * @global WP_Locale_Switcher $wp_locale_switcher * * @param string $locale The locale. * @return bool True on success, false on failure. */ function switch_to_locale( $locale ) { /* @var WP_Locale_Switcher $wp_locale_switcher */ global $wp_locale_switcher; return $wp_locale_switcher-&amp;amp;gt;switch_to_locale( $locale ); } /** * Restores the translations according to the previous locale. * * @since 4.7.0 * * @global WP_Locale_Switcher $wp_locale_switcher * * @return string|false Locale on success, false on error. */ function restore_previous_locale() { /* @var WP_Locale_Switcher $wp_locale_switcher */ global $wp_locale_switcher; return $wp_locale_switcher-&amp;amp;gt;restore_previous_locale(); } /** * Restores the translations according to the original locale. * * @since 4.7.0 * * @global WP_Locale_Switcher $wp_locale_switcher * * @return string|false Locale on success, false on error. */ function restore_current_locale() { /* @var WP_Locale_Switcher $wp_locale_switcher */ global $wp_locale_switcher; return $wp_locale_switcher-&amp;amp;gt;restore_current_locale(); } /** * Whether switch_to_locale() is in effect. * * @since 4.7.0 * * @global WP_Locale_Switcher $wp_locale_switcher * * @return bool True if the locale has been switched, false otherwise. */ function is_locale_switched() { /* @var WP_Locale_Switcher $wp_locale_switcher */ global $wp_locale_switcher; return $wp_locale_switcher-&amp;amp;gt;is_switched(); } [/code]

そのほかにもwp-cliや特定の状況下でうまくいかないことがあるようなので、リンクだけあげておきます。

サブディレクトリにインストールした
#45528 (load_script_textdomain() doesn’t load translations when WP installed in a subdirectory with custom content dir) – WordPress Trac

wp-cliで翻訳ファイルを更新した
#45488 (wp_set_script_translations does not load md5-based PO files) – WordPress Trac

プラグインを作る時にクラシックエディタと違っていた内容
Gutenberg と WordPress 5.0 のブロックエディターで違っていたところ – Snow Monkey