PEP-597: Emit a Warning when encoding is omitted

[ofek (Ofek Lev)]

Great idea! I’ll repeat what I said here: PEP 597: Use UTF-8 for default text file encoding - #82 by ofek

@ofek

Just my anecdotal 2c:

As a Windows-only user for the past 10+ years, the absolute only time I’ve written/read things in something other than UTF-8 was when burning in subtitles to video that were created by others. In these cases one can only guess and therefore chardet was used.

Having the default be UTF-8 would have saved me lots of pain over the years.