gcc version number from autotools

[Bob Rossi]

On Wed, Dec 20, 2006 at 09:09:33AM -0800, Ian Lance Taylor wrote:
> Bob Rossi <bob_rossi@cox.net> writes:
> 
> > What's the best way to get the gcc version number from an autotools
> > project? I could start gcc and parse the output. Could I write a small
> > program that checks some #define that has gcc's version number?
> 
> You can check __GNUC__, __GNUC_MINOR__, and __GNUC_PATCHLEVEL__.  Is
> that the sort of thing you are looking for?
> 
> > If so, how far back does that work for?
> 
> __GNUC__ and __GNUC_MINOR__ have been around for a long time,
> certainly since before gcc 3.0 (and, although I didn't check, probably
> before gcc 2.0).  I believe that __GNUC_PATCHLEVEL__ was added in gcc
> 3.0.

Thanks, here is what I did, in case others find it useful.

Bob Rossi

  AC_MSG_CHECKING([for $CC version])
  AC_RUN_IFELSE([AC_LANG_PROGRAM(
  [[#include <stdio.h>]], [[
        FILE *fp;
        fp = fopen("conftest.cc", "w");
        if (fp == 0) return(1);
        fprintf(fp, "ac_cv_cc_major_version=%d;ac_cv_cc_minor_version=%d;ac_cv_cc_patch_version=%d", 
                __GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__);
        fclose(fp);
  ]])],
            [eval `cat conftest.cc`],
            [ac_cv_cc_major_version=no])

  if test "$ac_cv_cc_major_version" = "no"; then
    AC_MSG_RESULT([no])
    AC_MSG_FAILURE(Requires that $CC is usable],[1])
  else
    ac_cv_cc_version="$ac_cv_cc_major_version.$ac_cv_cc_minor_version.$ac_cv_cc_patch_version"
    AC_MSG_RESULT([$ac_cv_cc_version])
  fi;