On Fri, Jan 13, 2017 at 8:12 PM, Dimitrios Apostolou <jimis@xxxxxxx> wrote: > > recent GCC versions default to C99 or even C11. I was expecting that adding > AC_PROG_CC_C89 to configure.ac, would force C89, probably by using > -std=gnu89. But this was not the case. Any ideas why? Originally, AC_PROG_CC_C89 meant "make sure the C compiler supports _at least_ C89". It was for programs that couldn't be compiled with a K&R compiler. (Remember that Autoconf has been around since the 1990s.) Nowadays, your use case is probably more common, but it's still rare enough that I doubt it makes sense for Autoconf to have a built-in feature for it. And I don't think we can safely change what AC_PROG_CC_C89 does. I would suggest manually splicing `-std=gnu89` into the CC variable (not CFLAGS) after AC_PROG_CC, conditional on $GCC. > /opt/csw/lib/gcc/i386-pc-solaris2.10/5.2.0/include-fixed/sys/feature_tests.h:346:2: > error: #error "Compiler or options invalid for pre-UNIX 03 X/Open > applications and pre-2001 POSIX applications" Solaris is tedious like that, yes. But did you really _want_ an old POSIX conformance level? I can see wanting POSIX.1-2001 specifically, since -2008 removed a number of useful things (gettimeofday, swapcontext, etc) but pre-2001 seems unlikely. You might try AC_USE_SYSTEM_EXTENSIONS. zw _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf
