bug#61190: 28.2; ispell personal dictionary location for hunspell engine

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 61190@debbugs.gnu.org
> Date: Tue, 31 Jan 2023 15:47:30 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> 
> Does it work for you as expected if you invoke Hunspell from the shell
> prompt like this:
> 
>   hunspell -d en_US -p c:/Users/xxx/.hunspell_en_US SOME-FILE
> 
> (which starts Hunspell with its own text-mode user interface), and
> then use the 'i' command inside Hunspell to save some words in the
> personal dictionary?  (I presume that your Hunspell supports the
> interactive invocation like above.)  If that doesn't save in the
> correct file either, then it's a Hunspell bug, and you should report
> it to the folks who develop Hunspell or those who produced the Windows
> port you are using.  Because all Emacs does when you set
> ispell-personal-directory is to invoke Hunspell with the "-p PDICT"
> command-line argument.  If you have Process Explorer installed, you
> should be able to verify that Hunspell is indeed invoked with the -p
> option as above, and if that is so, then the part of Emacs and
> ispell.el works correctly, and the problem is in Hunspell itself.

I looked into the Hunspell's sources, and I think I know why this
happens.  Hunspell has a peculiar logic when looking for the personal
dictionary.  The outcome of that peculiar logic is that if Hunspell is
invoked with "-p PDICT" command-line argument, and PDICT is an
absolute file name, that file must already exist, or else Hunspell
will decide it cannot use it.  And Emacs always invokes Hunspell with
an absolute file name of the personal dictionary.

This is arguably a bug in Hunspell, but a workaround is to create an
empty file at the location where you want the personal dictionary to
be, and then restart the speller.