Re: Weird failure with autoconf 2.69c in gmp

[Nick Bowler]

On 13/10/2020, Ross Burton <ross@burtonini.com> wrote:
> Hi,
>
> Using autoconf 2.69c (upgrading from 2.69b meant we could drop two
> patches, so that's good news!) to build gmp fails in a rather
> mysterious way:
[...]
> | m4:configure.ac:40: Warning: excess arguments to builtin `m4_define'
> ignored
> | autom4te: error: m4 failed with exit status: 1
> | aclocal: error: echo failed with exit status: 1
> | autoreconf: error: aclocal failed with exit status: 1
>
> Line 40 is:
>
> AC_INIT(GNU MP, GMP_VERSION, [gmp-bugs@gmplib.org, see
> https://gmplib.org/manual/Reporting-Bugs.html], gmp)
>
> Has anyone seen this, or similar, before?

This appears to be caused by a quoting bug in _AC_INIT_PACKAGE (expanded
by AC_INIT) which was recently introduced by commit 6a0c0239449a ("Trim
whitespace from arguments of AC_INIT").

It would seem that the comma from the 3rd argument ends up getting
passed unquoted to m4_define which results in this error.

This code in lib/autoconf/general.m4:

  m4_ifndef([AC_PACKAGE_BUGREPORT],
          [m4_define([AC_PACKAGE_BUGREPORT], _ac_init_BUGREPORT)])

should probably be changed to:

  m4_ifndef([AC_PACKAGE_BUGREPORT],
          [m4_define([AC_PACKAGE_BUGREPORT], m4_defn([_ac_init_BUGREPORT]))])

Cheers,
  Nick