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

["Daniel P. Berrangé" <berrange@redhat.com>]

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.

> +    sdl = declare_dependency(compile_args: '-Wno-undef',
> +                             dependencies: sdl,
> +                             version: sdl.version())
> +  endif
>    sdl_image = dependency('SDL2_image', required: get_option('sdl_image'),
>                           method: 'pkg-config')
>  else
> -- 
> 2.31.1
> 

With regards,
Daniel
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