Merge #14192: utils: Convert fs::filesystem_error messages from local multibyte to utf-8 on Windows

e2213689328f8ba42af1d32d12c7b78a71f1ddc7 utils: Convert fs error messages from multibyte to utf-8 (Chun Kuan Lee)

Pull request description:

  Before:
  ![default](https://user-images.githubusercontent.com/11154118/45318798-8d83f480-b570-11e8-8cbb-c729a54f6b9e.png)
  After:
  ![2](https://user-images.githubusercontent.com/11154118/45318806-91177b80-b570-11e8-9474-a62342c92dbd.png)

Tree-SHA512: 0a598bd159286f6784d117b8a24888b2650d5402d687ab0e8d0849e0c3d53797e266647d8177bb6614307c9598019cd7477311bb9895b1bb52a6bd77b460fda1

1 files changed, 16 insertions, 0 deletions

diff --git a/src/fs.cpp b/src/fs.cpp
index a34a88216a..df79b5e3df 100644
--- a/src/fs.cpp
+++ b/src/fs.cpp
@@ -97,4 +97,20 @@ bool FileLock::TryLock()
 }
 #endif
 
+std::string get_filesystem_error_message(const fs::filesystem_error& e)
+{
+#ifndef WIN32
+    return e.what();
+#else
+    // Convert from Multi Byte to utf-16
+    std::string mb_string(e.what());
+    int size = MultiByteToWideChar(CP_ACP, 0, mb_string.c_str(), mb_string.size(), nullptr, 0);
+
+    std::wstring utf16_string(size, L'\0');
+    MultiByteToWideChar(CP_ACP, 0, mb_string.c_str(), mb_string.size(), &*utf16_string.begin(), size);
+    // Convert from utf-16 to utf-8
+    return std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>, wchar_t>().to_bytes(utf16_string);
+#endif
+}
+
 } // fsbridge