meson: use a feature option for gallium-vdpau

Which we can use with the require method, and use the feature itself
as the require argument to dependency call. All of this results in less
code

Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20409>

meson.build

@@ -640,53 +640,27 @@ if with_gallium_d3d12 and not _with_gallium_d3d12_video.disabled()
   pre_args += '-DHAVE_GALLIUM_D3D12_VIDEO'
 endif
 
-_vdpau = get_option('gallium-vdpau')
+_vdpau_drivers = [
-if _vdpau == 'true'
+  with_gallium_d3d12_video,
-  _vdpau = 'enabled'
+  with_gallium_nouveau,
-  warning('gallium-vdpau option "true" deprecated, please use "enabled" instead.')
+  with_gallium_r300,
-elif _vdpau == 'false'
+  with_gallium_r600,
-  _vdpau = 'disabled'
+  with_gallium_radeonsi,
-  warning('gallium-vdpau option "false" deprecated, please use "disabled" instead.')
+  with_gallium_virgl,
-endif
+]
-if not system_has_kms_drm
-  if _vdpau == 'enabled'
-    error('VDPAU state tracker can only be build on unix-like OSes.')
-  else
-    _vdpau = 'disabled'
-  endif
-elif not with_platform_x11
-  if _vdpau == 'enabled'
-    error('VDPAU state tracker requires X11 support.')
-  else
-    _vdpau = 'disabled'
-  endif
-elif not [
-           with_gallium_d3d12_video,
-           with_gallium_nouveau,
-           with_gallium_r300,
-           with_gallium_r600,
-           with_gallium_radeonsi,
-           with_gallium_virgl,
-         ].contains(true)
-  if _vdpau == 'enabled'
-    error('VDPAU state tracker requires at least one of the following gallium drivers: r300, r600, radeonsi, nouveau, d3d12 (with option gallium-d3d12-video, virgl).')
-  else
-    _vdpau = 'disabled'
-  endif
-endif
-dep_vdpau = null_dep
-with_gallium_vdpau = false
-if _vdpau != 'disabled'
-  dep_vdpau = dependency('vdpau', version : '>= 1.1', required : _vdpau == 'enabled')
-  if dep_vdpau.found()
-    dep_vdpau = dep_vdpau.partial_dependency(compile_args : true)
-    with_gallium_vdpau = true
-  endif
-endif
 
-if with_gallium_vdpau
+vdpau = get_option('gallium-vdpau') \
+  .require(system_has_kms_drm, error_message : 'VDPAU state tracker can only be build on unix-like OSes.') \
+  .require(with_platform_x11, error_message : 'VDPAU state tracker requires X11 support.') \
+  .require(_vdpau_drivers.contains(true), error_message : 'VDPAU state tracker requires at least one of the following gallium drivers: r300, r600, radeonsi, nouveau, d3d12 (with option gallium-d3d12-video, virgl).') 
+
+dep_vdpau = dependency('vdpau', version : '>= 1.1', required : vdpau)
+if dep_vdpau.found()
+  dep_vdpau = dep_vdpau.partial_dependency(compile_args : true)
   pre_args += '-DHAVE_ST_VDPAU'
 endif
+with_gallium_vdpau = dep_vdpau.found()
+
 vdpau_drivers_path = get_option('vdpau-libs-path')
 if vdpau_drivers_path == ''
   vdpau_drivers_path = join_paths(get_option('libdir'), 'vdpau')

meson_options.txt

@@ -85,9 +85,7 @@ option(
 )
 option(
   'gallium-vdpau',
-  type : 'combo',
+  type : 'feature',
-  value : 'auto',
-  choices : ['auto', 'true', 'false', 'enabled', 'disabled'],
   description : 'enable gallium vdpau frontend.',
 )
 option(