https://github.com/fcitx/fcitx5-hangul/pull/14

Index: src/engine.h
--- src/engine.h.orig
+++ src/engine.h
@@ -85,7 +85,9 @@ typedef enum _LookupMethod {
 
 class HangulState;
 
-using UString = std::basic_string<uint32_t>;
+using UString = std::basic_string<char32_t>;
+
+UString ucsToUString(const ucschar *c);
 
 class HangulEngine : public InputMethodEngine {
 public:
