[PATCH 2/2] libXft: remove AC_PROG_CC as it overrides AC_PROG_C_C99

[Dan Nicholson]

On Wed, Jan 19, 2011 at 1:25 PM, Gaetan Nadon <memsize at videotron.ca> wrote:
> On Wed, 2011-01-19 at 12:51 -0800, Dan Nicholson wrote:
>
> This seems like more of a problem with the macros. I don't know why
> XORG_STRICT_OPTION doesn't just AC_REQUIRE AC_PROG_CC so that we don't
> get these kinds of issues.
>
> I have not found a way to avoid these issues. The last call wins.
> If C99 is invoked before AC_REQUIRE C89, C89 will win simply because
> it is not C99. They don't know about each other, even if some of the work
> they
> do is cached and reused by the other.
>
> However, for this particular case I think
> it would be better if we just moved the XORG_DEFAULT_OPTIONS call
> below AC_PROG_CC.
>
> The statements become order sensitive, which is hard to maintain, even
> when commented. The day will come where there will be a dead lock.
>
> If we comment or remove AC_PROG_CC, then it becomes
> really unclear that we're getting it implicitly through
> XORG_DEFAULT_OPTIONS.
>
> This is also true for any macro that is being invoked from
> XORG_DEFAULT_OPTIONS.
>
> The XORG_STRICT_OPTION was intended to "enforce" C99 by virtue of inclusion
> in configure.ac. It ceased to be "optional" once it got included in
> XORG_DEFAULT_OPTIONS.
>
> Other comments from reviewers so far indicate there is no objections to C99,
> with some pros and cons.
>
> The reason why AC_PROG_CC are removed is for the module to be compiled C99.
>
> If we find something better to do, it should be applied to all 240 modules,
> unless there
> is a reason to configure the modules with different compiler levels.

And if we later remove XORG_STRICT_OPTION from XORG_DEFAULT_OPTIONS
(which isn't a crazy suggestion), then there is nothing calling
AC_PROG_CC*. That's why I was suggesting to just move the
XORG_DEFAULT_OPTIONS call later so that the original call is still
there and it's not some implicit thing buried in another macro.

> To find out which version it is compiled with:
>
> grep "^CC=" `find . -name config.log -type f -print`
>
> For a C99:
>
> CC='gcc -std=gnu99'

We want to try to ensure that we get C99 if XORG_STRICT_OPTION is
used. So, if we AC_REQUIRE([AC_PROG_CC]) before
AC_REQUIRE([AC_PROG_CC_C99]) in XORG_STRICT_OPTION, then it should
ensure the ordering, right? Or can you just keep calling them and the
last one wins? I haven't checked.

--
Dan