Re: [PATCH v2] meson.build: Use -Wno-undef only for SDL2 versions that need it

[Thomas Huth <thuth@redhat.com>]

On 05/06/2023 10.53, Daniel P. Berrangé wrote:
> On Fri, Jun 02, 2023 at 06:34:52PM +0200, Thomas Huth wrote:
>> There is no need to disable this useful compiler warning for
>> all versions of the SDL. Unfortunately, various versions are
>> buggy (beside SDL 2.0.8, the version 2.26.0 and 2.26.1 are
>> broken, too, see https://github.com/libsdl-org/SDL/issues/6619 ),
>> but we can use a simple compiler check to see whether we need
>> the -Wno-undef or not.
>>
>> This also enables the printing of the version number with
>> good versions of the SDL in the summary of the meson output
>> again.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   v2: Compile test code instead of hard-coding the version number
>>
>>   meson.build | 14 ++++++++++----
>>   1 file changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/meson.build b/meson.build
>> index a61d3e9b06..a4c69616c3 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -1273,10 +1273,16 @@ if not get_option('sdl').auto() or have_system
>>     sdl_image = not_found
>>   endif
>>   if sdl.found()
>> -  # work around 2.0.8 bug
>> -  sdl = declare_dependency(compile_args: '-Wno-undef',
>> -                           dependencies: sdl,
>> -                           version: sdl.version())
>> +  # Some versions of SDL have problems with -Wundef
>> +  if not cc.compiles('''
>> +                     #include <SDL.h>
>> +                     #include <SDL_syswm.h>
>> +                     int main(int argc, char *argv[]) { return 0; }
>> +                     ''', dependencies: sdl, args: '-Wundef')
> 
> Don't you need to pass '-Werror' there too, otherwise -Wundef will
> merely generate an warning and still succeed.

Of course! Thank you very much ... not sure how I could have missed that 
detail :-/

  Thomas