[pulseaudio-discuss] [PATCH v3 14/24] build-sys: Move to compiling with C11 support

[Arun Raghavan]

On Thu, 2016-02-04 at 07:13 +0200, Tanu Kaskinen wrote:
> On Thu, 2016-02-04 at 10:30 +0530, Arun Raghavan wrote:
> > On 4 February 2016 at 10:22, Arun Raghavan <arun at accosted.net>
> > wrote:
> > > On Thu, 2016-02-04 at 06:04 +0200, Tanu Kaskinen wrote:
> > > > On Mon, 2016-01-18 at 13:06 +0530, arun at accosted.net wrote:
> > > > > @@ -176,6 +175,8 @@ esac
> > > > > 
> > > > >  #### Compiler flags ####
> > > > > 
> > > > > +AX_CHECK_COMPILE_FLAG([-std=c11], [CFLAGS="$CFLAGS
> > > > > -std=c11"], [],
> > > > > [-pedantic -Werror])
> > > > 
> > > > This does nothing if the compile flag isn't supported.
> > > > Shouldn't we
> > > > fail in configure if -std=c11 doesn't work?
> > > 
> > > Right, I'm rewriting this line as:
> > > 
> > > AX_CHECK_COMPILE_FLAG([-std=c11],
> > >    [CFLAGS="$CFLAGS -std=c11"],
> > >    [AC_MSG_ERROR([*** Compiler does not support -std=c11])],
> > >    [-pedantic -Werror])
> > > 
> > > > Also, I don't think we should set CFLAGS. Adding -std=c11 to
> > > > AM_CFLAGS
> > > > in src/Makefile.am seems like the right thing to do. See
> > > > https://www.gnu.org/software/automake/manual/html_node/User-Var
> > > > iables
> > > > .html#User-Variables
> > > 
> > > This would make it inconsistent with the rest of configure.ac,
> > > though.
> > > It'd be nice to change everything to use AM_CFLAGS but that
> > > should be a
> > > separate change.
> 
> I don't buy this argument. There's no consistency in the first place.
> We set some flags via CFLAGS and some via AM_CFLAGS.

Looking at this again, I don't see any place in the configure checks
where AM_CFLAGS is set (and it looks to me like that this would not be
appropriate anyway -- AM_CFLAGS seems meant to be used withing
Makefile.am, not configure.ac).

> > > One more thing that's missing in this change is an addition
> > > of ax_check_compile_flag.m4. I'll squash that in too.
> > 
> > The AX_* macros also seem to work with CFLAGS, btw.
> 
> What do you mean by that?

If you look at what AX_APPEND_COMPILE_FLAGS does, for example, it sets
CFLAGS directly.

-- Arun