Re: [PATCH] AC_LANG_INT_SAVE: Modernize function declarators (C89 and above).

[Paul Eggert]

On 8/5/20 10:32 AM, Vincent Lefevre wrote:
> With MPFR, it works after applying this patch.

I don't see it as working with MPFR. If you try to build MPFR 4.1.0 with 
"./configure CFLAGS='-g3 -O2 -Werror=old-style-definition'", then 'configure' 
makes some other wrong decisions on my platform (Fedora 31 x86-64). For example, 
'configure' doesn't "#define STDC_HEADERS 1" as it should, and it creates the 
wrong value for global_symbol_pipe and for global_symbol_to_cdecl in the 
'libtool' file.

Perhaps none of these mistakes happened to bite you in your tests, but the point 
is that it's always been a bad idea to use -Werror in 'configure', and saying 
that something doesn't work when one configures with -Werror is not a good 
motivation for making a change to Autoconf.