Use en-US as fallback when using other default language (#21200) (#21256)

Only en-US has complete translations. When use other language as
default, the en-US should still be used as fallback.

Backport #21200, Close #21199

modules/translation/i18n/i18n.go

@@ -41,14 +41,14 @@ func NewLocaleStore() *LocaleStore {
 }
 
 // AddLocaleByIni adds locale by ini into the store
-func (ls *LocaleStore) AddLocaleByIni(langName, langDesc string, localeFile interface{}, otherLocaleFiles ...interface{}) error {
+func (ls *LocaleStore) AddLocaleByIni(langName, langDesc string, source, moreSource []byte) error {
 	if _, ok := ls.localeMap[langName]; ok {
 		return ErrLocaleAlreadyExist
 	}
 	iniFile, err := ini.LoadSources(ini.LoadOptions{
 		IgnoreInlineComment:         true,
 		UnescapeValueCommentSymbols: true,
-	}, localeFile, otherLocaleFiles...)
+	}, source, moreSource)
 	if err == nil {
 		iniFile.BlockMode = false
 		lc := &locale{store: ls, langName: langName, langDesc: langDesc, messages: iniFile}

modules/translation/i18n/i18n_test.go

@@ -10,7 +10,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func Test_Tr(t *testing.T) {
+func TestLocaleStore(t *testing.T) {
 	testData1 := []byte(`
 .dot.name = Dot Name
 fmt = %[1]s %[2]s
@@ -28,8 +28,8 @@ sub = Changed Sub String
 `)
 
 	ls := NewLocaleStore()
-	assert.NoError(t, ls.AddLocaleByIni("lang1", "Lang1", testData1))
-	assert.NoError(t, ls.AddLocaleByIni("lang2", "Lang2", testData2))
+	assert.NoError(t, ls.AddLocaleByIni("lang1", "Lang1", testData1, nil))
+	assert.NoError(t, ls.AddLocaleByIni("lang2", "Lang2", testData2, nil))
 	ls.SetDefaultLang("lang1")
 
 	result := ls.Tr("lang1", "fmt", "a", "b")
@@ -54,3 +54,21 @@ sub = Changed Sub String
 	assert.Equal(t, []string{"lang1", "lang2"}, langs)
 	assert.Equal(t, []string{"Lang1", "Lang2"}, descs)
 }
+
+func TestLocaleStoreMoreSource(t *testing.T) {
+	testData1 := []byte(`
+a=11
+b=12
+`)
+
+	testData2 := []byte(`
+b=21
+c=22
+`)
+
+	ls := NewLocaleStore()
+	assert.NoError(t, ls.AddLocaleByIni("lang1", "Lang1", testData1, testData2))
+	assert.Equal(t, "11", ls.Tr("lang1", "a"))
+	assert.Equal(t, "21", ls.Tr("lang1", "b"))
+	assert.Equal(t, "22", ls.Tr("lang1", "c"))
+}

modules/translation/translation.go

@@ -60,9 +60,9 @@ func InitLocales() {
 		log.Fatal("Failed to list locale files: %v", err)
 	}
 
-	localFiles := make(map[string][]byte, len(localeNames))
+	localeData := make(map[string][]byte, len(localeNames))
 	for _, name := range localeNames {
-		localFiles[name], err = options.Locale(name)
+		localeData[name], err = options.Locale(name)
 		if err != nil {
 			log.Fatal("Failed to load %s locale file. %v", name, err)
 		}
@@ -75,8 +75,16 @@ func InitLocales() {
 
 	matcher = language.NewMatcher(supportedTags)
 	for i := range setting.Names {
+		var localeDataBase []byte
+		if i == 0 && setting.Langs[0] != "en-US" {
+			// Only en-US has complete translations. When use other language as default, the en-US should still be used as fallback.
+			localeDataBase = localeData["locale_en-US.ini"]
+			if localeDataBase == nil {
+				log.Fatal("Failed to load locale_en-US.ini file.")
+			}
+		}
 		key := "locale_" + setting.Langs[i] + ".ini"
-		if err = i18n.DefaultLocales.AddLocaleByIni(setting.Langs[i], setting.Names[i], localFiles[key]); err != nil {
+		if err = i18n.DefaultLocales.AddLocaleByIni(setting.Langs[i], setting.Names[i], localeDataBase, localeData[key]); err != nil {
 			log.Error("Failed to set messages to %s: %v", setting.Langs[i], err)
 		}
 	}