On Windows, we might reject bytes filenames for all file operations: open(), unlink(), os.path.join(), etc. (raise a TypeError or UnicodeError)
Since I've seen no objections to this yet: please no. If we offer a "lower-level" bytes filename API, it should work for all platforms.
Unfortunately, it can't. You cannot represent all possible file names in a byte string in Windows (just as you can't do so in a Unicode string on Unix). So using byte strings on Windows would work for some files, but fail for others. In particular, listdir might give you a list of file names which you then can't open/stat/recurse into. (of course, you could use UTF-8 as the file system encoding on Windows, but then you will have to rewrite a lot of C code first) Regards, Martin