meson: use the wayland module

This module has existed, unchanged, since Meson 0.64, and is now marked
as API stable in 1.8. It provides a number of helpers that reduce the
amount of code we need (including fiddly code about finding
wayland-scanner) by a bit, as well as some nice helpers for finding
external XML files.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35839>

meson.build

@@ -1999,13 +1999,6 @@ endif
 
 with_wayland_bind_display = with_platform_wayland and get_option('legacy-wayland').contains('bind-wayland-display')
 if with_platform_wayland
-  dep_wl_scanner = dependency('wayland-scanner', native: true)
-  prog_wl_scanner = find_program(dep_wl_scanner.get_variable(pkgconfig : 'wayland_scanner'))
-  if dep_wl_scanner.version().version_compare('>= 1.15')
-    wl_scanner_arg = 'private-code'
-  else
-    wl_scanner_arg = 'code'
-  endif
   dep_wl_protocols = dependency('wayland-protocols', version : '>= 1.41', default_options: [ 'tests=false' ])
   dep_wayland_client = dependency('wayland-client', version : '>=1.18')
   dep_wayland_server = dependency('wayland-server', version : '>=1.18')
@@ -2026,6 +2019,8 @@ if with_platform_wayland
       dependencies: dep_wayland_client)
     pre_args += ['-DHAVE_WL_CREATE_QUEUE_WITH_NAME']
   endif
+  # This can be renamed just `wayland` when we require at least 1.8
+  mod_wl = import('unstable-wayland')
 endif
 
 # Even if we find OpenMP, Gitlab CI fails to link with gcc/i386 and clang/anyarch.

src/egl/wayland/wayland-drm/meson.build

@@ -3,26 +3,10 @@
 
 inc_wayland_drm = include_directories('.')
 
-wayland_drm_protocol_c = custom_target(
+_wl_drm = mod_wl.scan_xml('wayland-drm.xml', server : true, include_core_only : false)
-  'wayland-drm-protocol.c',
+wayland_drm_protocol_c = _wl_drm[0]
-  input : 'wayland-drm.xml',
+wayland_drm_client_protocol_h = _wl_drm[1]
-  output : 'wayland-drm-protocol.c',
+wayland_drm_server_protocol_h = _wl_drm[2]
-  command : [prog_wl_scanner, wl_scanner_arg, '@INPUT@', '@OUTPUT@'],
-)
-
-wayland_drm_client_protocol_h = custom_target(
-  'wayland-drm-client-protocol.h',
-  input : 'wayland-drm.xml',
-  output : 'wayland-drm-client-protocol.h',
-  command : [prog_wl_scanner, 'client-header', '@INPUT@', '@OUTPUT@'],
-)
-
-wayland_drm_server_protocol_h = custom_target(
-  'wayland-drm-server-protocol.h',
-  input : 'wayland-drm.xml',
-  output : 'wayland-drm-server-protocol.h',
-  command : [prog_wl_scanner, 'server-header', '@INPUT@', '@OUTPUT@'],
-)
 
 libwayland_drm = static_library(
   'wayland_drm',

src/loader/meson.build

@@ -4,31 +4,18 @@
 inc_loader = include_directories('.')
 
 if with_platform_wayland
-  wp_dir = dep_wl_protocols.get_variable(pkgconfig : 'pkgdatadir', internal : 'pkgdatadir')
   wp_protos = {
-    'fifo-v1': 'staging/fifo/fifo-v1.xml',
+    'fifo-v1': mod_wl.find_protocol('fifo', state : 'staging', version : 1),
-    'commit-timing-v1': 'staging/commit-timing/commit-timing-v1.xml',
+    'commit-timing-v1': mod_wl.find_protocol('commit-timing', state : 'staging', version : 1),
-    'linux-dmabuf-unstable-v1': 'unstable/linux-dmabuf/linux-dmabuf-unstable-v1.xml',
+    'linux-dmabuf-unstable-v1': mod_wl.find_protocol('linux-dmabuf', state : 'unstable', version : 1),
-    'presentation-time': 'stable/presentation-time/presentation-time.xml',
+    'presentation-time': mod_wl.find_protocol('presentation-time'),
-    'tearing-control-v1': 'staging/tearing-control/tearing-control-v1.xml',
+    'tearing-control-v1': mod_wl.find_protocol('tearing-control', state : 'staging', version : 1),
-    'linux-drm-syncobj-v1': 'staging/linux-drm-syncobj/linux-drm-syncobj-v1.xml',
+    'linux-drm-syncobj-v1': mod_wl.find_protocol('linux-drm-syncobj', state : 'staging', version : 1),
-    'color-management-v1': 'staging/color-management/color-management-v1.xml',
+    'color-management-v1': mod_wl.find_protocol('color-management', state : 'staging', version : 1)
   }
   wp_files = {}
   foreach name, xml : wp_protos
-    code = custom_target(
+    wp_files += {name : mod_wl.scan_xml(xml, include_core_only : false)}
-      name + '-protocol.c',
-      input : files(join_paths(wp_dir, xml)),
-      output : name + '-protocol.c',
-      command : [prog_wl_scanner, wl_scanner_arg, '@INPUT@', '@OUTPUT@'],
-    )
-    header = custom_target(
-      name + '-client-protocol.h',
-      input : files(join_paths(wp_dir, xml)),
-      output : name + '-client-protocol.h',
-      command : [prog_wl_scanner, 'client-header', '@INPUT@', '@OUTPUT@'],
-    )
-    wp_files += { name: [code, header] }
   endforeach
 
   libloader_wayland_helper = static_library(