[IMPORTANT] Dropping support for split '.info' files in mainline Automake

[Stefano Lattarini]

Severity: wishlist

[This is posted also to the automake and texinfo lists to ensure
 a wider audience.  Discussion should continue exclusively on the
 bug-automake list, to avoid a cross-posting flood]

Automake-generated have for a long time supported "split" info files:
<http://www.gnu.org/software/texinfo/manual/texinfo/texinfo.html#Tag-and-Split-Files>

When I asked the rationale for this feature:

  <http://lists.gnu.org/archive/html/texinfo-devel/2012-08/msg00015.html>

Karl Berry confirmed that the reason for its existence was indeed
"efficiency, especially memory size":

  <http://lists.gnu.org/archive/html/texinfo-devel/2012-08/msg00024.html>

He also added that "The Elisp manual is one of the largest ones around.
Looks like it would be maybe 3.5mb as one file."  Not in any way big by
modern standards.

OTOH, it appears that the use of split info files (at least in the way
Automake-generated rules have been handling them for a long time) can
cause real problems in some (admittedly quite corner-case) situations:

  <http://thread.gmane.org/gmane.comp.parsers.bison.bugs/3963>
  <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12320>

So I believe we could follow suit with Automake-NG (see commit dd603e21,
<http://lists.gnu.org/archive/html/automake-ng/2012-08/msg00147.html>)
and have Automake-generated makefiles pass the '--no-split' option
unconditionally to makeinfo invocations (starting from Automake 1.14).
This would allow some nice simplifications in our Texinfo recipe
(exemplified by the Automake-NG patch referenced above), and offer an
automatic fix for bug#12320.

Another *very* good aspect of such a change is that it would be 100%
transparent to the Automake users.

Thoughts, opinions, objections?

Regards,
  Stefano