Leave NULL impl pointer in wxUILocale if locale is not supported

This finally seems better than always creating some kind of impl object,
even if the locale isn't supported at all and makes all ports behave
consistently, as previously CreateForLocale() only returned NULL in
wxOSX implementation if the locale was unrecognized, but now all ports
do this (at least when locale_t and related functions are available
under Unix).

Also stop returning bool from Use(), as this resulted in initializing
wxLocale with any non-default language to fail under Mac: just ignore
the error here, as we always did it until now, because there is nothing
we can do about it anyhow.

src/msw/uilocale.cpp

@@ -114,12 +114,9 @@ public:
     {
     }
 
-    bool Use() wxOVERRIDE
+    void Use() wxOVERRIDE
     {
         wxUseLCID(m_lcid);
-
-        // As long as we use a valid LCID (and we always do), it shouldn't fail.
-        return true;
     }
 
     wxString GetName() const wxOVERRIDE
@@ -200,18 +197,31 @@ public:
         return s_canUse == 1;
     }
 
-    // Note that "name" can be NULL here (LOCALE_NAME_USER_DEFAULT).
-    explicit wxUILocaleImplName(const wchar_t* name)
-        : m_name(name ? wxStrdup(name) : NULL)
+    // Create object corresponding to the default user locale.
+    static wxUILocaleImplName* CreateDefault()
     {
+        return new wxUILocaleImplName(LOCALE_NAME_USER_DEFAULT);
     }
 
+    // Create object corresponding to the given locale, return NULL if not
+    // supported.
+    static wxUILocaleImplName* Create(const wchar_t* name)
+    {
+        // Getting the locale name seems to be the simplest way to see if it's
+        // really supported: unknown locale result in an error here.
+        if ( !ms_GetLocaleInfoEx(name, LOCALE_SNAME, NULL, 0) )
+            return NULL;
+
+        return new wxUILocaleImplName(name);
+    }
+
+
     ~wxUILocaleImplName() wxOVERRIDE
     {
         free(const_cast<wchar_t*>(m_name));
     }
 
-    bool Use() wxOVERRIDE
+    void Use() wxOVERRIDE
     {
         // Construct a double NUL-terminated buffer.
         wchar_t buf[256];
@@ -224,9 +234,7 @@ public:
         ULONG num = 1;
 
         if ( !ms_SetThreadPreferredUILanguages(MUI_LANGUAGE_NAME, buf, &num) )
-            return false;
-
-        return true;
+            wxLogLastError(wxT("SetThreadPreferredUILanguages"));
     }
 
     wxString GetName() const wxOVERRIDE
@@ -331,6 +339,15 @@ private:
                                             LPARAM);
     static CompareStringEx_t ms_CompareStringEx;
 
+
+    // Ctor is private, use CreateDefault() or Create() instead.
+    //
+    // Note that "name" can be NULL here (LOCALE_NAME_USER_DEFAULT).
+    explicit wxUILocaleImplName(const wchar_t* name)
+        : m_name(name ? wxStrdup(name) : NULL)
+    {
+    }
+
     wxString DoGetInfo(LCTYPE lctype) const
     {
         wchar_t buf[256];
@@ -366,7 +383,7 @@ wxUILocaleImpl* wxUILocaleImpl::CreateStdC()
         return new wxUILocaleImplLCID(lcid);
     }
 
-    return new wxUILocaleImplName(L"en-US");
+    return wxUILocaleImplName::Create(L"en-US");
 }
 
 /* static */
@@ -375,7 +392,7 @@ wxUILocaleImpl* wxUILocaleImpl::CreateUserDefault()
     if ( !wxUILocaleImplName::CanUse() )
         return new wxUILocaleImplLCID(LOCALE_USER_DEFAULT);
 
-    return new wxUILocaleImplName(LOCALE_NAME_USER_DEFAULT);
+    return wxUILocaleImplName::CreateDefault();
 }
 
 /* static */
@@ -403,7 +420,7 @@ wxUILocaleImpl* wxUILocaleImpl::CreateForLocale(const wxLocaleIdent& locId)
         return NULL;
     }
 
-    return new wxUILocaleImplName(locId.GetName());
+    return wxUILocaleImplName::Create(locId.GetName().wc_str());
 }
 
 #endif // wxUSE_INTL