convert message back to wchar

include/spdlog/sinks/win_eventlog_sink.h

@@ -39,6 +39,8 @@ Windows Registry Editor Version 5.00
 #include <mutex>
 #include <string>
 #include <vector>
+#include <locale>
+#include <codecvt>
 
 namespace spdlog {
 namespace sinks {
@@ -55,34 +57,20 @@ struct win32_error : public spdlog_ex
     {
         std::string system_message;
 
-        auto fFormatResult = [&system_message](bool format_message_succeeded, void* format_message_result)
-        {
-            if (format_message_succeeded && format_message_result)
-            {
-                system_message = fmt::format(" ({})", format_message_result);
-            }
-
-            if (format_message_result)
-            {
-                LocalFree((HLOCAL)format_message_result);
-            }
-        };
-
-#ifdef SPDLOG_WCHAR_TO_UTF8_SUPPORT
-        LPWSTR format_message_result{};
-        auto format_message_succeeded =
-            ::FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
-                error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPWSTR)&format_message_result, 0, nullptr);
-
-        fFormatResult(format_message_succeeded, format_message_result);
-#else
         LPSTR format_message_result{};
         auto format_message_succeeded =
             ::FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
                 error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&format_message_result, 0, nullptr);
 
-        fFormatResult(format_message_succeeded, format_message_result);
-#endif
+        if (format_message_succeeded && format_message_result)
+        {
+            system_message = fmt::format(" ({})", format_message_result);
+        }
+
+        if (format_message_result)
+        {
+            LocalFree((HLOCAL)format_message_result);
+        }
 
         return fmt::format("{}: {}{}", user_message, error_code, system_message);
     }
@@ -238,10 +226,10 @@ protected:
         formatted.push_back('\0');
 
 #ifdef SPDLOG_WCHAR_TO_UTF8_SUPPORT
-            LPCWSTR lp_str = reinterpret_cast<LPCWSTR>(formatted.data());
+            auto buf = std::wstring_convert<std::codecvt_utf8<wchar_t>>().from_bytes(formatted.data());
 
             succeeded = ::ReportEventW(event_log_handle(), eventlog::get_event_type(msg), eventlog::get_event_category(msg), event_id_,
-                current_user_sid_.as_sid(), 1, 0, &lp_str, nullptr);
+                current_user_sid_.as_sid(), 1, 0, (LPCWSTR*)buf.c_str(), nullptr);
 #else
             LPCSTR lp_str = reinterpret_cast<LPCSTR>(formatted.data());