Re: Prefer luatex for documentation

[Werner LEMBERG]

>> What I'm now working on are macros for `configure.ac` to find a
>> UTF-8 locale, which is important for the documentation generation
>> in the long run.  [...]
> 
> Phooey, that sounds complicated.  I wonder if it would not take just
>  as much time to reimplement texindex in Perl, as suggested in
>  https://lists.gnu.org/archive/html/bug-texinfo/2022-11/msg00022.html
>  … (It would also benefit everyone using indices in Texinfo.)

`texindex` is just one part of the problem.[*]  We also need a UTF-8
locale for both `makeinfo` and `lilypond-book` – without it, the
output for both PDF and HTML is simply wrong.  My standard example is
the incorrect display of the degree sign in the documentation of the
'\rotate' markup command:

  https://lilypond.org/doc/v2.23/Documentation/notation/align

In other words, such a test for `configure.ac` is inevitable.  We
might fix `lilypond-book` to emit a warning or even abort if it can't
switch to a UTF-8 locale internally, but `makeinfo` (and soon
`texi2any`, as a replacement for `texi2html`) is out of our control.


    Werner


[*] Even if rewritten in Perl, we eventually need language-specific
    locales to get correct collation in indices.  This means that for
    building the German documentation, `de_DE.UTF-8` should be used,
    etc., etc.  For this, however, there are ready-to-use autoconf
    macros available in 'gnulib'.  If there are better suggestions to
    avoid such additional locale tests, I'm all ears.