bug#21554: no previous prototype for 'set_binary_mode'

[Paul Eggert]

On 09/25/2015 12:40 AM, Benno Schulenberg wrote:
>    CC     argmatch.o
> cc1: warning: command line option "-Wenum-compare" is valid for C++/ObjC++ but 
> not for C
>    CC     binary-io.o
> cc1: warning: command line option "-Wenum-compare" is valid for C++/ObjC++ but 
> not for C
> cc1: warnings being treated as errors
> In file included from binary-io.c:3:
> binary-io.h:53: error: no previous prototype for 'set_binary_mode'

Thanks, I managed to reproduce this on an old RHEL 6 server we have.  It 
uses GCC 4.4.7, which is too old for use with --enable-gcc-warnings.  
Please configure without --enable-gcc-warnings and build it that way; it 
should build fine. That is, a plain './configure; make; make check' 
should work.  (Of course you may run into problems with your old buggy 
libpcre, but that's a different story....)

Nowadays I don't recommend RHEL 6 for use when maintaining GNU software, 
as it has too many old versions of development programs (as you already 
discovered for Autoconf).  It's OK to use it to build from distribution 
tarballs, but not for building from git.

I.e., let's not worry about this build-time problem; instead, let's 
focus on the bug report's original grep-2.21 issue, whatever that issue is.