Re: [Qemu-devel] [PATCH] configure: use -Wwombat to test whether gcc recognizes -Wno-wombat

[Stefan Weil <sw@weilnetz.de>]

Am 27.10.2012 23:19, schrieb Peter Maydell:
> gcc will silently accept unrecognized -Wno-wombat warning suppression
> options (it only mentions them if it has to print a compiler warning
> for some other reason). Since we already run a check for whether gcc
> recognizes the warning options we use, we can easily make this use
> the positive sense of the option when checking for support for the
> suppression option. This doesn't have any effect except that it avoids
> gcc emitting extra messages about unrecognized command line options
> when it is printing other warning messages.
>
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
>   configure | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/configure b/configure
> index 37f712d..4c2ba06 100755
> --- a/configure
> +++ b/configure
> @@ -1169,7 +1169,11 @@ cat>  $TMPC<<  EOF
>   int main(void) { return 0; }
>   EOF
>   for flag in $gcc_flags; do
> -    if compile_prog "-Werror $flag" "" ; then
> +    # Use the positive sense of the flag when testing for -Wno-wombat
> +    # support (gcc will happily accept the -Wno- form of unknown
> +    # warning options).
> +    optflag="$(echo $flag | sed -e 's/^-Wno-/-W/')"
> +    if compile_prog "-Werror $optflag" "" ; then
>   	QEMU_CFLAGS="$QEMU_CFLAGS $flag"
>       fi
>   done

Yes, that's really a very simple and working solution.

Reviewed-by: Stefan Weil <sw@weilnetz.de>