Re: [POLL] C99, declaration after statement

[Paul Eggert]

On 09/25/11 09:35, Bruno Haible wrote:
> AC_PROG_CC_C99 should then be preferred over AC_PROG_CC_STDC. Right?

No, because one cannot safely mix
AC_PROG_CC_C99 and AC_PROG_CC_STDC, just
as one cannot safely mix AC_PROG_CC_STDC
and AC_PROG_CC_C89, or safely mix
AC_PROG_CC_C89 and AC_PROG_CC_C99.

Perhaps Autoconf could be improved so that
these macros can be used together, but that
would require some thought: in a few places
C89 is genuinely incompatible with C99, and
I expect the same will be true with C1x.

In the past, we've ignored this issue: thus,
even though gnulib modules generally require
C89 or better, gnulib doesn't invoke AC_PROG_CC_C89.
On further thought, perhaps we should continue
to ignore it.