bug#81332: info/dir and INFO_NONMISC are not gated by DOCLANGS

> Date: Tue, 28 Jul 2026 15:23:40 +0000
> From: Boris <[email protected]>
> Cc: Eli Zaretskii <[email protected]>, Vincent Belaiche <[email protected]>
> 
> The bug is closed and this is not a regression from the patches, so this is just a question: is the remaining DOCLANGS inconsistency worth fixing? I mentioned it when Vincent and I discussed the empty DOCLANGS case, and I said I could take it as a follow-up.
> 
> Two places still hardcode the three built-in manuals:
> 
> - srcdir_doc_info_dir_inputs lists doc/emacs/emacs.texi, doc/lispintro/emacs-lisp-intro.texi and doc/lispref/elisp.texi unconditionally, while the misc entries are gated (texi_misc_default only exists when default is in DOCLANGS)
> - INFO_NONMISC lists the same three .info files for install-info
> 
> The visible effect is with DOCLANGS='fr' (or any set without default): emacs-info, lispintro-info and lispref-info are no-ops, so those manuals are never built, but info/dir still lists them, and install-info still runs install-info on them. The latter is invisible today only because the recipe ignores errors.

THose 3 manuals must always be built and always be installed,
regardless of DOCLANGS.  The first two are referenced from various doc
strings, and the 3rd one (Lisp Intro) is important enough part of
Emacs to be available regardless of the language preferences of the
user who builds the manuals.

> Gating both on $(filter default,$(DOCLANGS)) is a small change. One detail: build-aux/make-info-dir starts with "test $# -ge 2 || exit 1", so with empty DOCLANGS everything would be gated away and "make info" would fail instead of generating a dir file. I would relax that to -ge 1, so info/dir is still generated with the header and no entries.

Can we do that without involving build-aux/ files?  Those files are
from Gnulib, so I'd prefer our local tricks to be just ours.

Thanks.