bug#44318: 28.0.50; Problem with ispell/flyspell and ""enchant"" backend

[Reuben Thomas]

On Mon, 2 Nov 2020 at 16:10, Eli Zaretskii <eliz@gnu.org> wrote:

> From: Reuben Thomas <rrt@sc3d.org>
> Date: Mon, 2 Nov 2020 15:49:19 +0000
> Cc: dinkonin <dinkonin@gmail.com>, 44318@debbugs.gnu.org
>
> So I, as upstream maintainer, am telling you that indeed, it is not correct that Emacs should take
> enchant-lsmod's stderr as part of its output! (As I said above, it would be possible to capture stderr
> separately and display it to the user, though I don't recommend that currently, because the warnings are not
> written for users. Other programs that use Enchant do not show these warnings, they simply omit providers
> that do not load from the list of languages/spelling checkers that are available.)

OK, I agree to this change, under protest.

Thanks Eli, I have installed it; of course, contact me if it causes any problems. After installing that patch, I discovered that in ispell--call-enchant-lsmod, it did need to use with-current-buffer, so I have installed a patch that restores the use of with-current-buffer; apologies for getting that wrong first time.

In fact, this change is not sufficient to fix the original problem, because the enchant program outputs the same warning when a provider module cannot be loaded. In this case, stderr is added to the list of suggested words. Again, I believe Enchant is correct to output a warning, and again, I believe Emacs is wrong to amalgamate stderr and stdout.

I attach three patches that do the following:

1. Simplify ispell-call-process{,-region} by factoring out the macro ispell-with-safe-default-directory.

2. I also found that ispell-check-version can be simplified slightly: aspell has accepted -vv since 2004, so use it always.

3. When spell-checking, collect only standard output. This leaves some spell-checker-specific calls to ispell-call-process to collect stderr as well, which as far as I can tell is needed in only one case, ispell-find-hunspell-dictionaries; but it doesn't hurt to leave the rest unchanged. I have tested this patch with all supported spellcheckers (ispell, aspell, hunspell, enchant).

0002-Factor-out-some-common-code-in-ispell.el.patch
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0001-Simplify-ispell-check-version-s-use-of-vv-flag.patch
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0003-Prevent-ispell-being-confused-by-spellchecker-output.patch
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