Re: [PATCH v2 6/8] configure: Pass filtered QEMU_OBJCFLAGS to meson

[Paolo Bonzini]

On 2/15/22 18:01, Philippe Mathieu-Daudé via wrote:
> Filter unsupported Objective-C options, to avoid
> 'unknown-warning-option' warnings when using Clang:
>
>    [34/373] Compiling Objective-C object libcommon.fa.p/audio_coreaudio.m.o
>    warning: unknown warning option '-Wold-style-declaration'; did you mean 
> '-Wout-of-line-declaration'? [-Wunknown-warning-option]
>    warning: unknown warning option '-Wimplicit-fallthrough=2'; did you mean 
> '-Wimplicit-fallthrough'? [-Wunknown-warning-option]
>    2 warnings generated.
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Acked-by: Paolo Bonzini <pbonzini@redhat.com>

> ---
>   configure   | 23 +++++++++++++++++++++++
>   meson.build |  5 ++++-
>   2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/configure b/configure
> index 3217aa22cb..df6eaec067 100755
> --- a/configure
> +++ b/configure
> @@ -77,6 +77,7 @@ TMPB="qemu-conf"
>   TMPC="${TMPDIR1}/${TMPB}.c"
>   TMPO="${TMPDIR1}/${TMPB}.o"
>   TMPCXX="${TMPDIR1}/${TMPB}.cxx"
> +TMPM="${TMPDIR1}/${TMPB}.m"
>   TMPE="${TMPDIR1}/${TMPB}.exe"
>   
>   rm -f config.log
> @@ -148,6 +149,10 @@ do_cxx() {
>       do_compiler "$cxx" $CPU_CFLAGS "$@"
>   }
>   
> +do_objc() {
> +    do_compiler "$objcc" $CPU_CFLAGS "$@"
> +}
> +
>   # Append $2 to the variable named $1, with space separation
>   add_to() {
>       eval $1=\${$1:+\"\$$1 \"}\$2
> @@ -1616,10 +1621,27 @@ cc_has_warning_flag() {
>       compile_prog "-Werror $optflag" ""
>   }
>   
> +objcc_has_warning_flag() {
> +    cat > $TMPM <<EOF
> +int main(void) { return 0; }
> +EOF
> +
> +    # Use the positive sense of the flag when testing for -Wno-wombat
> +    # support (gcc will happily accept the -Wno- form of unknown
> +    # warning options).
> +    optflag="$(echo $1 | sed -e 's/^-Wno-/-W/')"
> +    do_objc -Werror $optflag \
> +      $OBJCFLAGS $EXTRA_OBJCFLAGS $CONFIGURE_OBJCFLAGS $QEMU_OBJCFLAGS \
> +      -o $TMPE $TMPM $QEMU_LDFLAGS
> +}
> +
>   for flag in $gcc_flags; do
>       if cc_has_warning_flag $flag ; then
>           QEMU_CFLAGS="$QEMU_CFLAGS $flag"
>       fi
> +    if objcc_has_warning_flag $flag ; then
> +        QEMU_OBJCFLAGS="$QEMU_OBJCFLAGS $flag"
> +    fi
>   done
>   
>   if test "$stack_protector" != "no"; then
> @@ -3579,6 +3601,7 @@ echo "LD=$ld" >> $config_host_mak
>   echo "CFLAGS_NOPIE=$CFLAGS_NOPIE" >> $config_host_mak
>   echo "QEMU_CFLAGS=$QEMU_CFLAGS" >> $config_host_mak
>   echo "QEMU_CXXFLAGS=$QEMU_CXXFLAGS" >> $config_host_mak
> +echo "QEMU_OBJCFLAGS=$QEMU_OBJCFLAGS" >> $config_host_mak
>   echo "GLIB_CFLAGS=$glib_cflags" >> $config_host_mak
>   echo "GLIB_LIBS=$glib_libs" >> $config_host_mak
>   echo "GLIB_VERSION=$(pkg-config --modversion glib-2.0)" >> $config_host_mak
> diff --git a/meson.build b/meson.build
> index 215c253683..7b78235a39 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -199,9 +199,11 @@ if get_option('fuzzing')
>   endif
>   
>   add_global_arguments(config_host['QEMU_CFLAGS'].split(),
> -                     native: false, language: ['c', 'objc'])
> +                     native: false, language: ['c'])
>   add_global_arguments(config_host['QEMU_CXXFLAGS'].split(),
>                        native: false, language: 'cpp')
> +add_global_arguments(config_host['QEMU_OBJCFLAGS'].split(),
> +                     native: false, language: ['objc'])
>   add_global_link_arguments(config_host['QEMU_LDFLAGS'].split(),
>                             native: false, language: ['c', 'cpp', 'objc'])
>   
> @@ -3306,6 +3308,7 @@ if link_args.length() > 0
>   endif
>   summary_info += {'QEMU_CFLAGS':       config_host['QEMU_CFLAGS']}
>   summary_info += {'QEMU_CXXFLAGS':     config_host['QEMU_CXXFLAGS']}
> +summary_info += {'QEMU_OBJCFLAGS':    config_host['QEMU_OBJCFLAGS']}
>   summary_info += {'QEMU_LDFLAGS':      config_host['QEMU_LDFLAGS']}
>   summary_info += {'profiler':          config_host.has_key('CONFIG_PROFILER')}
>   summary_info += {'link-time optimization (LTO)': get_option('b_lto')}