[wayland] Refactor layout diversity check using std::optional

Author: sophiel-meow

src/modules/wayland/waylandmodule.cpp

@@ -746,23 +746,27 @@ void WaylandModule::selfDiagnose() {
 
         // layout diagnosis only when overriding is enabled
         if (*config_.allowOverrideXKB) {
-            std::unordered_set<std::string> groupLayouts;
+            std::optional<std::string> firstLayout;
             for (const auto &groupName :
                  instance_->inputMethodManager().groups()) {
                 if (const auto *group =
                         instance_->inputMethodManager().group(groupName)) {
-                    groupLayouts.insert(group->defaultLayout());
-                }
-                if (groupLayouts.size() >= 2) {
-                    messages.push_back(
-                        _("Sending keyboard layout configuration to wayland "
-                          "compositor from Fcitx is "
-                          "not yet supported on current desktop. You may still "
-                          "use "
-                          "Fcitx's internal layout conversion by adding layout "
-                          "as "
-                          "input method to the input method group."));
-                    break;
+                    const auto &layout = group->defaultLayout();
+                    if (!firstLayout) {
+                        firstLayout = layout;
+                    } else if (layout != *firstLayout) {
+                        messages.push_back(_(
+                            "Sending keyboard layout configuration to wayland "
+                            "compositor from Fcitx is "
+                            "not yet supported on current desktop. You may "
+                            "still "
+                            "use "
+                            "Fcitx's internal layout conversion by adding "
+                            "layout "
+                            "as "
+                            "input method to the input method group."));
+                        break;
+                    }
                 }
             }
         }