meson: Make libdisplay_info a feature option

Some features depend on libdisplay-info, and making it a feature
option should increase its visibility and adoption.

This makes it required when building with "-Dauto_features=enabled",
unless explicitly disabled with "-Dlibdisplay_info=disabled".

If "-Dauto_features=enabled" is not set, everything remains the
same.

In the future, the libdisplay_info option can be made "enabled" by
default so that it would always be required unless explicitly
disabled.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3582>

.gitlab-ci.yml

@@ -324,7 +324,7 @@ check-code-style:
       -Degl_device=true
       -Dwayland_eglstream=true
       -Dcatch=true
-      -Dlibdisplay_info=true
+      -Dlibdisplay_info=enabled
 
 .build-mutter:
   extends:

meson.build

@@ -168,10 +168,9 @@ if have_x11_client
   xau_dep = dependency('xau')
 endif
 
-have_libdisplay_info = get_option('libdisplay_info')
-if have_libdisplay_info
-  libdisplay_info_dep = dependency('libdisplay-info')
-endif
+use_libdisplay_info = get_option('libdisplay_info')
+libdisplay_info_dep = dependency('libdisplay-info', required: use_libdisplay_info)
+have_libdisplay_info = libdisplay_info_dep.found()
 
 have_gnome_desktop = get_option('libgnome_desktop')
 if have_gnome_desktop

meson_options.txt

@@ -226,7 +226,8 @@ option('catch',
 )
 
 option('libdisplay_info',
-  type: 'boolean',
-  value: false,
+  type: 'feature',
+  value: 'auto',
+  deprecated: {'true': 'enabled', 'false': 'disabled'},
   description: 'Build with or without libdisplay-info'
 )