Re: autoconf-2.69c released [beta]

[Gavin Smith]

On Fri, Sep 25, 2020 at 9:07 PM Gavin Smith <gavinsmith0123@gmail.com> wrote:
>
> > * Warnings about obsolete constructs are now on by default.
> >   They can be turned off with '-Wno-obsolete'.
> >
>
> I have tried building the git development version of Texinfo with
> the new autoconf, but am deluged with warnings.  I get the following
> warnings from autoconf:
>
> configure.ac:87: warning: The macro `AC_GNU_SOURCE' is obsolete.
> configure.ac:87: You should run autoupdate.
> ./lib/autoconf/specific.m4:312: AC_GNU_SOURCE is expanded from...
> gnulib/m4/gnulib-comp.m4:34: gl_EARLY is expanded from...
> configure.ac:87: the top level

I found it hard to track down where the AC_GNU_SOURCE use was coming
from, and the path "lib/autoconf/specific.m4" is incorrect for the
file "specific.m4". By searching for the text AC_GNU_SOURCE in all
project files as well as installed autoconf files, as well as looking
at the log files under autom4te.cache, I suspect it is coming from the
"extensions.m4" file from Gnulib. (I don't know why that file isn't
named in the error messages, though.) This has the following
definition:

# gl_USE_SYSTEM_EXTENSIONS
# ------------------------
# Enable extensions on systems that normally disable them,
# typically due to standards-conformance issues.
AC_DEFUN_ONCE([gl_USE_SYSTEM_EXTENSIONS],
[
  dnl Require this macro before AC_USE_SYSTEM_EXTENSIONS.
  dnl gnulib does not need it. But if it gets required by third-party macros
  dnl after AC_USE_SYSTEM_EXTENSIONS is required, autoconf 2.62..2.63 emit a
  dnl warning: "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".
  dnl Note: We can do this only for one of the macros AC_AIX, AC_GNU_SOURCE,
  dnl AC_MINIX. If people still use AC_AIX or AC_MINIX, they are out of luck.
  AC_REQUIRE([AC_GNU_SOURCE])

  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
])

Would it be right to say that this should be changed in Gnulib,
otherwise any project using that file with Gnulib will have errors
from the new autoconf?