On Tue, Aug 16, 2016 at 10:53 AM, Paul Moore
Having said all this, I can't find the documentation stating that bytes paths are deprecated - the open() documentation for 3.5 says "file is either a string or bytes object giving the pathname (absolute or relative to the current working directory) of the file to be opened or an integer file descriptor of the file to be wrapped" and there's no mention of a deprecation.
Bytes paths aren't deprecated on Unix -- only on Windows, and only for the os functions. You can see the deprecation warning with -Wall: >>> os.listdir(b'.') __main__:1: DeprecationWarning: The Windows bytes API has been deprecated, use Unicode filenames instead AFAIK this isn't documented. Since the Windows CRT's _open implementation uses MultiByteToWideChar without the flag MB_ERR_INVALID_CHARS, bytes paths should also be deprecated for io.open. The problem is that bad DBCS sequences are mapped silently to the default Unicode character instead of raising an error.