Ok to keep calls to ANSI versions of the Windows API when bytes filenames are used (so get question marks on encoding errors).

> Another alternative would be to switch to UTF-8 as the file system encoding on Windows, but that change might be too incompatible.

On Linux, I tried to have more than one "OS" encoding and it was a big fail (search for "PYTHONFSENCODING" env var in Python history). It introduced many new tricky issues. In short, Python should use the same "OS encoding" *everyone*. Since they are many places where Python doesn't control the encoding, we must use the same encoding than the OS. For example, os.listdir(b'.') uses the ANSI code page. If you concatenate two strings, one encoding to UTF-8 and the other encoded to the ANSI code page, you will at least see mojibake, and your operation will probably fail (ex: unable to open the file).

I mean that forcing an encoding *everywhere* is a losing battle. There are too many external functions using the locale encoding on UNIX and the ANSI code page on Windows. Not only in the C library, think also to OpenSSL just to give you one example.

Anyway, bytes filenames are deprecated since Python 3.2 so it's maybe time to stop using them!

--

Another alternative is to completly drop support of bytes filenames on Windows in Python 3.5. But I expect that too many applications will just fail. It's too early for such disruptive change.

So I'm just closing the issue as "not a bug", because Python just follows the vendor choice (Microsoft decided to use funny question marks :-)).