[cairo] [PATCH 2/2] configure : fix unrecognized -Wno option

[Chris Wilson]

On Sun, 21 Oct 2012 12:59:06 +0200 (CEST), g.esp at free.fr wrote:
> This behavior is described in gcc-4.4 announce http://gcc.gnu.org/gcc-4.4/changes.html
> and on later versions in the manual
> http://gcc.gnu.org/onlinedocs/gcc-4.7.2/gcc/Warning-Options.html#Warning-Options
> 
> A new option has even be added after gcc-4.4 to control that behavior with -Wunknown-warning/-Wno-unknown-warning but as this new option is not know on gcc-4.4, the new option can't be used there unless using the same trick aka test if -Wunknown-warning is supported and use -Wno-unknown-warning. So there is actually no gain with that option until the last supported compiler know this new option.
> 
> Detection was made in a similar way in openssh(portable) or using makefile in linux/scripts/Kbuild.include with
> # cc-disable-warning
> # Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
> cc-disable-warning = $(call try-run,\
> 	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))

Thanks for the information. So my conclusion is that this patch looks
to be the lesser evil, and so I've applied it.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre