Re: [RFC PATCH v3 1/7] configure: Allow passing extra Objective C compiler flags

[Philippe Mathieu-Daudé]

+Paolo who I forgot to Cc.

On 1/11/22 18:16, Roman Bolshakov wrote:
> On Mon, Jan 10, 2022 at 02:09:55PM +0100, Philippe Mathieu-Daudé wrote:
>> We can pass C/CPP/LD flags via CFLAGS/CXXFLAGS/LDFLAGS environment
>> variables, or via configure --extra-cflags / --extra-cxxflags /
>> --extra-ldflags options. Provide similar behavior for Objective C:
>> use existing flags from $OBJCFLAGS, or passed via --extra-objcflags.
>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>  configure   | 8 ++++++++
>>  meson.build | 5 +++++
>>  2 files changed, 13 insertions(+)
>>
>> diff --git a/configure b/configure
>> index 0c57a063c66..adb42d8beb1 100755
>> --- a/configure
>> +++ b/configure
>> @@ -288,6 +288,7 @@ done
>>  
>>  EXTRA_CFLAGS=""
>>  EXTRA_CXXFLAGS=""
>> +EXTRA_OBJCFLAGS=""
>>  EXTRA_LDFLAGS=""
>>  
>>  xen_ctrl_version="$default_feature"
>> @@ -400,9 +401,12 @@ for opt do
>>    --extra-cflags=*)
>>      EXTRA_CFLAGS="$EXTRA_CFLAGS $optarg"
>>      EXTRA_CXXFLAGS="$EXTRA_CXXFLAGS $optarg"
>> +    EXTRA_OBJCFLAGS="$EXTRA_OBJCFLAGS $optarg"
>>      ;;
>>    --extra-cxxflags=*) EXTRA_CXXFLAGS="$EXTRA_CXXFLAGS $optarg"
>>    ;;
>> +  --extra-objcflags=*) EXTRA_OBJCFLAGS="$EXTRA_OBJCFLAGS $optarg"
>> +  ;;
>>    --extra-ldflags=*) EXTRA_LDFLAGS="$EXTRA_LDFLAGS $optarg"
>>    ;;
>>    --enable-debug-info) debug_info="yes"
>> @@ -781,6 +785,8 @@ for opt do
>>    ;;
>>    --extra-cxxflags=*)
>>    ;;
>> +  --extra-objcflags=*)
>> +  ;;
>>    --extra-ldflags=*)
>>    ;;
>>    --enable-debug-info)
>> @@ -1318,6 +1324,7 @@ Advanced options (experts only):
>>    --objcc=OBJCC            use Objective-C compiler OBJCC [$objcc]
>>    --extra-cflags=CFLAGS    append extra C compiler flags CFLAGS
>>    --extra-cxxflags=CXXFLAGS append extra C++ compiler flags CXXFLAGS
>> +  --extra-objcflags=OBJCFLAGS append extra Objective C compiler flags 
>> OBJCFLAGS
>>    --extra-ldflags=LDFLAGS  append extra linker flags LDFLAGS
>>    --cross-cc-ARCH=CC       use compiler when building ARCH guest test cases
>>    --cross-cc-flags-ARCH=   use compiler flags when building ARCH guest tests
>> @@ -3843,6 +3850,7 @@ if test "$skip_meson" = no; then
>>    echo "[built-in options]" >> $cross
>>    echo "c_args = [$(meson_quote $CFLAGS $EXTRA_CFLAGS)]" >> $cross
>>    echo "cpp_args = [$(meson_quote $CXXFLAGS $EXTRA_CXXFLAGS)]" >> $cross
>> +  test -n "$objcc" && echo "objc_args = [$(meson_quote $OBJCFLAGS 
>> $EXTRA_OBJCFLAGS)]" >> $cross
>>    echo "c_link_args = [$(meson_quote $CFLAGS $LDFLAGS $EXTRA_CFLAGS 
>> $EXTRA_LDFLAGS)]" >> $cross
>>    echo "cpp_link_args = [$(meson_quote $CXXFLAGS $LDFLAGS $EXTRA_CXXFLAGS 
>> $EXTRA_LDFLAGS)]" >> $cross
>>    echo "[binaries]" >> $cross
>> diff --git a/meson.build b/meson.build
>> index 0e52f54b100..a21305d62c1 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -3286,6 +3286,11 @@
>>                                                 + ['-O' + 
>> get_option('optimization')]
>>                                                 + (get_option('debug') ? 
>> ['-g'] : []))}
>>  endif
>> +if targetos == 'darwin'
>> +  summary_info += {'OBJCFLAGS':       ' '.join(get_option('objc_args')
>> +                                               + ['-O' + 
>> get_option('optimization')]
>> +                                               + (get_option('debug') ? 
>> ['-g'] : []))}
> 
> Hi Philippe,
> 
> You need to add something like below to actually use the flags in build:
> 
> add_global_arguments(config_host['QEMU_OBJCFLAGS'].split(),
>                      native: false, language: 'objc')


But so far we don't need any particular QEMU_OBJCFLAGS, so I rather not
add unused code. This patch simply adds passing ObjC flags from
"./configure --extra-objcflags=".

Anyway, with your/Akihiko/Christian help during review, this flag
is not necessary anymore to build softmmu/tools (I still have to
figure how to silent the "#pragma FENV_ACCESS" warning in tests),
so let forget about this patch (except if we expect macOS ObjC to
keep evolving and need a way to pass OBJCFLAGS).