[Mesa-dev] [PATCH] meson: do not search for needless deps

[Gert Wollny]

Am Mittwoch, den 25.10.2017, 10:24 +0200 schrieb Erik Faye-Lund:
> If we don't want to use these deps, there's no good reason to search
> for them in the first place. This should shave a bit of time for the
> initial build.
> ---
> 
> This would be a way of dealing with Gert's suggestion. Goes on top
> of the previous patch.
> 
> Thoughts?
> 
>  meson.build | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/meson.build b/meson.build
> index e842bb1652..201956c4c8 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -666,9 +666,13 @@ if with_glvnd
>  endif
>  
>  # TODO: make this conditional
> -dep_valgrind = dependency('valgrind', required : false)
> -if dep_valgrind.found() and with_valgrind
> -  pre_args += '-DHAVE_VALGRIND'
> +if with_valgrind
> +  dep_valgrind = dependency('valgrind', required : false)
> +  if dep_valgrind.found()
> +    pre_args += '-DHAVE_VALGRIND'
> +  endif
> +else
> +  dep_valgrind = []
>  endif
>  
>  # pthread stubs. Lets not and say we didn't
> @@ -681,9 +685,13 @@ dep_selinux = []
>  
>  # TODO: llvm-prefix and llvm-shared-libs
>  
> -dep_unwind = dependency('libunwind', required : false)
> -if dep_unwind.found() and with_libunwind
> -  pre_args += '-DHAVE_LIBUNWIND'
> +if with_libunwind
> +  dep_unwind = dependency('libunwind', required : false)
> +  if dep_unwind.found()
> +    pre_args += '-DHAVE_LIBUNWIND'
> +  endif
> +else
> +  dep_unwind = []
>  endif
>  
>  # TODO: flags for opengl, gles, dri

Obviously, I like this more, but after reviewing what is done with the
autotools, I think it would be preferable if meson would do the same
i.e. with autotools 

  --enable-libunwind=no -> don't use libunwind 
  --enable-libunwind=yes -> require libunwind 

and if not given, then use it if available. The "force using libunwind"
option is currently missing.

I don't know yet how to use meson properly, but I guess one could
achieve this  by something like (put in the apropriate files): 

option('with_libunwind', 
        type : 'combo', 
        choices : ['auto', 'yes', 'no'])

if with_libunwind != 'no'
  dep_unwind = dependency('libunwind', 
                           required : with_libunwind == 'yes')
  if dep_unwind.found()
    pre_args += '-DHAVE_LIBUNWIND'
  endif
else
  dep_unwind = []
endif

Best, 
Gert