Re: [Qemu-devel] [PATCH] clang: Disable warning about expansion to 'defined'

[Paolo Bonzini]

On 09/08/2016 04:35, Pranith Kumar wrote:
> Clang produces the following warning. The warning is detailed here:
> https://reviews.llvm.org/D15866. Disable the warning.
> 
> /home/pranith/devops/code/qemu/hw/display/qxl.c:507:5: warning: macro 
> expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
> #if SPICE_NEEDS_SET_MM_TIME
>     ^
> /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded 
> from macro 'SPICE_NEEDS_SET_MM_TIME'
>   (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06))
>     ^
> /home/pranith/devops/code/qemu/hw/display/qxl.c:1074:5: warning: macro 
> expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
> #if SPICE_NEEDS_SET_MM_TIME
>     ^
> /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded 
> from macro 'SPICE_NEEDS_SET_MM_TIME'
>   (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06))
> 
> Signed-off-by: Pranith Kumar <address@hidden>
> ---
>  configure | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/configure b/configure
> index f57fcc6..a1a6e3f 100755
> --- a/configure
> +++ b/configure
> @@ -3025,6 +3025,19 @@ if ! compile_prog "$glib_cflags -Werror" "$glib_libs" 
> ; then
>      fi
>  fi
>  
> +# Silence clang warnings about expansion to 'defined' in macro
> +cat > $TMPC << EOF
> +#define TEST (defined(DUMMY))
> +#if TEST
> +int main(void) { return 0; }
> +#endif
> +EOF
> +if ! compile_prog "-Werror" ; then
> +    if cc_has_warning_flag "-Wno-expansion-to-defined"; then
> +     CFLAGS="-Wno-expansion-to-defined $CFLAGS"
> +    fi
> +fi
> +
>  ##########################################
>  # SHA command probe for modules
>  if test "$modules" = yes; then
> 

Can you just add it to gcc_flags instead?

Thanks,

Paolo