Gui: Default Translator::SetLocale to OS locale + simplify code

src/Gui/DlgGeneralImp.cpp

@@ -144,7 +144,7 @@ void DlgGeneralImp::setNumberLocale(bool force/* = false*/)
         return;
 
     if (localeFormat == 0) {
-        Translator::instance()->setSystemLocale();
+        Translator::instance()->setLocale(); // Defaults to system locale
     }
     else if (localeFormat == 1) {
         QByteArray current = ui->Languages->itemData(ui->Languages->currentIndex()).toByteArray();

src/Gui/Language/Translator.cpp

@@ -252,26 +252,23 @@ std::string Translator::locale(const std::string& lang) const
     return loc;
 }
 
-bool Translator::setLocale(const std::string& language) const
+void Translator::setLocale(const std::string& language) const
 {
-    auto loc = QLocale::c(); //Defaulting to POSIX locale
-    auto bcp47 = locale(language);
-    if (!bcp47.empty())
-        loc  = QLocale(QString::fromStdString(bcp47));
+    auto loc = QLocale::system(); //Defaulting to OS locale
+    if (language == "C" || language == "c") {
+        loc = QLocale::c();
+    }
+    else {
+        auto bcp47 = locale(language);
+        if (!bcp47.empty())
+            loc  = QLocale(QString::fromStdString(bcp47));
+    }
     QLocale::setDefault(loc);
     updateLocaleChange();
 
 #ifdef FC_DEBUG
     Base::Console().Log("Locale changed to %s => %s\n", qPrintable(loc.bcp47Name()), qPrintable(loc.name()));
 #endif
-
-    return (loc.language() != loc.C);
-}
-
-void Translator::setSystemLocale() const
-{
-    QLocale::setDefault(QLocale::system());
-    updateLocaleChange();
 }
 
 void Translator::updateLocaleChange() const

src/Gui/Language/Translator.h

@@ -66,9 +66,8 @@ public:
     std::string activeLanguage() const;
     /** Returns the locale (e.g. "de") to the given language name. */
     std::string locale(const std::string&) const;
-    /** Sets default Qt locale based on given language name. Returns true if matching QLocale found**/
-    bool setLocale(const std::string&) const;
-    void setSystemLocale() const;
+    /** Sets default Qt locale based on given language name **/
+    void setLocale(const std::string& = "") const;
     /** Returns a list of supported languages. */
     TStringList supportedLanguages() const;
     /** Returns a map of supported languages/locales. */