bug#42602: Wrong (not-)casechars value for "polish" in ispell-dictionary-base-alist

[Eli Zaretskii <eliz@gnu.org>]

> From: Sebastian Urban <mrsebastianurban@gmail.com>
> Cc: 42602@debbugs.gnu.org
> Date: Thu, 30 Jul 2020 13:39:55 +0200
> 
> > I don't understand this change.  Values above octal 377 cannot be
> > right in the above regexps, because they are supposed to be in
> > Latin-2 encoding, which is a single-byte encoding, and so can only
> > handle values below octal 400.  How did you come up with those
> > values?
> 
> Basically, C-x = on a char, which gave me octal values.

This gives you the Unicode codepoint, not its Latin-2 encoding.  They
are different.  The database in ispell.el uses Latin-2 encodings of
Polish characters.

> Well, I did some tests, e.g. switched back to the original value of
> "polish" in my "pl" dictionary, and... it works.  And if I change from
> iso-8859-2 to utf-8 in my "pl" (with original value from "polish") it
> doesn't work.  So, as you later wrote - wrong character encoding,
> I guess.
> 
> Looking for a cause (in default settings), I think I found it in
> ispell-dictionary-base-alist and ispell-dictionary-alist.  During
> "transfer" from *-base-* to ispell-dictionary-alist, the value of
> CHARACTER-SET is changed in all cases from iso-* or cp1255 to utf-8,
> then ispell uses these (from ispell-dictionary-alist) when it "talks"
> with Aspell.
> 
> On the other hand, if I use Emacs 26.3 from Cygwin, everything works
> out of the box, I don't even have to set "polish" as default
> dictionary. But there, in Cygwin command line, "env | grep LANG" gives
> "LANG=pl_PL.UTF-8".

Native MinGW builds cannot use the UTF-8 encoding.

So, do we have a problem to solve, or can this issue be closed?