Fall back to language name for translations lookup if locale name fails

For locales like de_AT, the current code only looks in
share/locale/de_AT/ and share/locale/de-AT/ for translation catalogs,
but not in share/locale/de/ where they most likely are.
That's because bcp47Name() returns "de-AT" for de_AT (though in the
case of de_DE e.g. it does return "de").

This patch additionally tries to fall back to the general language by
taking the part of the locale name before the first '_'.

Differential Revision: https://phabricator.kde.org/D9793

2 files changed, 11 insertions, 2 deletions

diff --git a/modules/ECMQmLoader.cpp.in b/modules/ECMQmLoader.cpp.in
index 12a2d146..f636ecc4 100644
--- a/modules/ECMQmLoader.cpp.in
+++ b/modules/ECMQmLoader.cpp.in
@@ -65,7 +65,12 @@ namespace {
         QLocale locale = QLocale::system();
         if (locale.name() != QStringLiteral("en")) {
             if (!loadTranslation(locale.name())) {
-                loadTranslation(locale.bcp47Name());
+                if (!loadTranslation(locale.bcp47Name())) {
+                    const int i = locale.name().indexOf(QLatin1Char('_'));
+                    if (i > 0) {
+                        loadTranslation(locale.name().left(i));
+                    }
+                }
             }
         }
     }
diff --git a/tests/ECMPoQmToolsTest/check.cmake.in b/tests/ECMPoQmToolsTest/check.cmake.in
index aeef8e42..26320584 100644
--- a/tests/ECMPoQmToolsTest/check.cmake.in
+++ b/tests/ECMPoQmToolsTest/check.cmake.in
@@ -58,16 +58,20 @@ endif()
 if("@CMAKE_SYSTEM_NAME@" STREQUAL "Linux")
     set(exp_output_catalog_en "english text:english plural form 5")
     set(exp_output_catalog_de "german text:german plural form 5")
+    # no de_AT translation -> should fall back to de
+    set(exp_output_catalog_de_AT "${exp_output_catalog_de}")
     # no french translation provided -> english fallback
     set(exp_output_catalog_fr "${exp_output_catalog_en}")
 
     set(exp_output_catalog2_en "2nd english text:2nd english plural form 5")
     set(exp_output_catalog2_de "2nd german text:2nd german plural form 5")
+    # no de_AT translation -> should fall back to de
+    set(exp_output_catalog2_de_AT "${exp_output_catalog2_de}")
     # no french translation provided -> english fallback
     set(exp_output_catalog2_fr "${exp_output_catalog2_en}")
 
     function(check_translations name exec catalog_name)
-        foreach(lang en de fr)
+        foreach(lang en de de_AT fr)
             execute_process(
                 COMMAND "${CMAKE_COMMAND}" -E env "XDG_DATA_DIRS=${ACTUAL_TREE}/share"
                     LANGUAGE=${lang} "${exec}"