lang/i18n: Fix for language code case issue with pt-br etc.

Fixes #7804

langs/config.go

@@ -36,7 +36,7 @@ type LanguagesConfig struct {
 
 func LoadLanguageSettings(cfg config.Provider, oldLangs Languages) (c LanguagesConfig, err error) {
 
-	defaultLang := cfg.GetString("defaultContentLanguage")
+	defaultLang := strings.ToLower(cfg.GetString("defaultContentLanguage"))
 	if defaultLang == "" {
 		defaultLang = "en"
 		cfg.Set("defaultContentLanguage", defaultLang)

langs/i18n/i18n.go

@@ -66,12 +66,11 @@ func (t Translator) Func(lang string) translateFunc {
 func (t Translator) initFuncs(bndl *i18n.Bundle) {
 	enableMissingTranslationPlaceholders := t.cfg.GetBool("enableMissingTranslationPlaceholders")
 	for _, lang := range bndl.LanguageTags() {
-
 		currentLang := lang
 		currentLangStr := currentLang.String()
-		currentLangKey := strings.TrimPrefix(currentLangStr, artificialLangTagPrefix)
+		// This may be pt-BR; make it case insensitive.
+		currentLangKey := strings.ToLower(strings.TrimPrefix(currentLangStr, artificialLangTagPrefix))
 		localizer := i18n.NewLocalizer(bndl, currentLangStr)
-
 		t.translateFuncs[currentLangKey] = func(translationID string, templateData interface{}) string {
 
 			var pluralCount interface{}

langs/i18n/i18n_test.go

@@ -226,6 +226,18 @@ one =  "abc"`),
 		expected:     "Show Me The Money",
 		expectedFlag: "Show Me The Money",
 	},
+	// https: //github.com/gohugoio/hugo/issues/7804
+	{
+		name: "lang-with-hyphen",
+		data: map[string][]byte{
+			"pt-br.toml": []byte(`foo.one =  "abc"`),
+		},
+		args:         1,
+		lang:         "pt-br",
+		id:           "foo",
+		expected:     "abc",
+		expectedFlag: "abc",
+	},
 }
 
 func doTestI18nTranslate(t testing.TB, test i18nTest, cfg config.Provider) string {