Fix up on Windows

src/platform_win.cc

@@ -9,6 +9,9 @@
 #include <fcntl.h>
 #include <io.h>
 #include <windows.h>
+#include <Shlobj.h>
+#include <Objbase.h>
+#include <Knownfolders.h>
 
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -17,6 +20,8 @@
 #include <cassert>
 #include <iostream>
 #include <string>
+#include <locale>
+#include <codecvt>
 
 namespace {
 void EmitError(const std::string& message) {
@@ -353,7 +358,7 @@ optional<std::string> RunExecutable(const std::vector<std::string>& command,
 
 optional<std::string> GetGlobalConfigDirectory() {
 	wchar_t  *roaming_path = NULL;
-	optional<std::string> cfg_path = std::nullopt;
+	optional<std::string> cfg_path = {};
 	if (SUCCEEDED(SHGetKnownFolderPath(FOLDERID_RoamingAppData, KF_FLAG_DEFAULT,
 					   NULL, &roaming_path))) {
 	  std::wstringstream roaming_stream;
@@ -363,10 +368,10 @@ optional<std::string> GetGlobalConfigDirectory() {
 	  // is analogous with the string returned by the posix version.
 	  using convert_type = std::codecvt_utf8<wchar_t>;
 	  std::wstring_convert<convert_type, wchar_t> converter;
-	  cfg_path = converter.to_bytes(roaming_stream.str())
+	  cfg_path = converter.to_bytes(roaming_stream.str());
 	}
 	CoTaskMemFree(static_cast<void*>(roaming_path));
-	return cfg_path
+	return cfg_path;
 }
 
 #endif