bug#49901: Bug in build c-ares [too many loops]

[Karl Berry]

I searched for "too many loops" in the bug-automake list archive.
It has been previously reported several times. Seems to be related to
autoconf-archive, especially the AX_CXX_COMPILE_STDCXX_14 macro
(or related, presumably).

In https://bugs.gnu.org/47848, I found a suggestion in the code that
rerunning aclocal may be necessary if files are installed.

https://bugs.gnu.org/25250 reports that rerunning aclocal sufficed.

https://bugs.gnu.org/24807 and especially https://bugs.gnu.org/23639
have an idea for the actual culprit:
    ... first run of autoreconf fails when I use
    AX_CXX_COMPILE_STDCXX_14 macro from autoconf-archive (version
    2016.03.20-r1 installed via portage on Gentoo), and only when I use
    it.  Second run immediately after it just works.

In https://lists.gnu.org/archive/html/bug-automake/2010-01/msg00006.html
Ralf writes, in response to the problem going away with a new release:
    This typically shows up when the macro file aclocal finds have some
    inconsistency, or aclocal finds macros from a different Libtool version
    that those which libtoolize installs into your package, or you have old
    macro files lying around in your package somewhere, possibly
    concatenated in some old aclocal.m4 or acinclude.m4 file.
(So, quite plausible that autoconf-archive is involved.)

So far as I saw (maybe I missed it), none of these reports, other than
yours, include an actual failing case that can be rerun.

With this info, can you cut down your c-ares project to a small test
that tries to exercise AX_CXX_COMPILE_STDCXX_14 or whatever you are
using? That would make it a lot more plausible to debug.

Anyway, adding this info for the record in case someone has the time and
energy to look further (which would be fantastic). --thanks, karl.