Ticket #28197: fallback-languages.diff

wp-includes/l10n.php

@@ -452 +452 @@
          * @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;
+        if ( !is_readable( $mofile ) ) {
+                $mofile = get_fallback_translations( $mofile, $domain );
 
+                if ( false === $mofile ) {
+                        return false;
+                }
+        }
+
         $mo = new MO();
         if ( !$mo->import_from_file( $mofile ) ) return false;
 
@@ -468 +475 @@
 }
 
 /**
+ * Looks for fallback translation files to use if locale is not available.
+ *
+ * @since 4.0.0
+ *
+ * @param string $domain Text domain. Unique identifier for retrieving translated strings.
+ * @param string $mofile Path to the .mo file.
+ * @return false or string $mofile Path
+ */
+function get_fallback_translations( $mofile, $domain ) {
+
+        $languages = get_available_languages( dirname( $mofile ) );
+
+        if ( empty( $languages ) ) {
+                return false;
+        }
+
+        $locale_base = substr( get_locale(), 0, 2);
+
+        foreach ( $languages as $language ) {
+                $language_base = substr( $language, -5, 2);
+                if ( $locale_base == $language_base ) {
+                        $alt_mofile = dirname( $mofile ) . '/' . $language . '.mo';
+                        $mofile = apply_filters( 'load_textdomain_mofile', $alt_mofile, $domain );
+                        if ( is_readable( $mofile ) ) {
+                                return $mofile;
+                        }
+                }
+        }
+
+        return false;
+}
+
+/**
  * Unload translations for a text domain.
  *
  * @since 3.0.0