Re: bug: "gcc -std=gnu99" passes AC_PROG_CC_C11

[Paul Eggert]

On 09/27/2012 10:04 AM, Adrian Bunk wrote:
> I merely wanted to point out that there can be a difference in what 
> glibc provides when we end up with gnu99 instead of gnu11.

Yes.  And programs using Autoconf will surely prefer the gnu11
version, which is why defaulting to gnu11 is a win.

> AC_PROG_CC_C99 in autoconf 2.69 has a documented semantics what C99
> features are guaranteed to be available when ac_cv_prog_cc_c99 is
> not "no".

True.  And those semantics still hold for git Autoconf, even if they're
marked as obsolete.
 
> Perhaps mode setting and feature reporting to autoconf users should be 
> less coupled for C11?

Yes, quite possibly.

> In any case, autoconf has to provide an easy and documented way for 
> users to get information on the C11 features available.

That should be a further set of macros, one for each such feature
that can't easily be tested with what Autoconf has now.  (There's
no need for Autoconf to worry about static_assert, for example,
since code can just use '#ifdef static_assert').