build: Use Xwayland pkg-config if available

Xwayland in its main development branch now provides a pkg-config file
which can be used to determine Xwayland installation path and various
options enabled at build time.

Change mutter build system to optionally use that mechanism if
available. If not (as with Xwayland from the current stable branch),
keep the fallback mechanisms (basically search for the Xwayland and parse
its command line options to determine if initfd is available).

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1635>

1 files changed, 16 insertions, 4 deletions

diff --git a/meson.build b/meson.build
index 782a8e364..c9d50514e 100644
--- a/meson.build
+++ b/meson.build
@@ -392,9 +392,15 @@ endif
 
 have_xwayland_initfd = false
 if have_wayland
+  xwayland_dep = dependency('xwayland', required: false)
+
   xwayland_path = get_option('xwayland_path')
   if xwayland_path == ''
-    xwayland_path = find_program('Xwayland').path()
+    if xwayland_dep.found()
+      xwayland_path = xwayland_dep.get_pkgconfig_variable('xwayland')
+    else
+      xwayland_path = find_program('Xwayland').path()
+    endif
   endif
   cdata.set_quoted('XWAYLAND_PATH', xwayland_path)
 
@@ -409,12 +415,18 @@ if have_wayland
 
   # For Xwayland -initfd usage
   use_initfd = get_option('xwayland_initfd')
-  xwayland_options = run_command(xwayland_path, '-help')
+  if xwayland_dep.found()
+    xwayland_supports_initfd = xwayland_dep.get_pkgconfig_variable('have_initfd') == 'true'
+  else
+    xwayland_options = run_command(xwayland_path, '-help')
+    xwayland_supports_initfd = xwayland_options.stderr().contains('-initfd')
+  endif
+
   if use_initfd.auto()
-    have_xwayland_initfd = xwayland_options.stderr().contains('-initfd')
+    have_xwayland_initfd = xwayland_supports_initfd
   else
     have_xwayland_initfd = use_initfd.enabled()
-    if have_xwayland_initfd and not xwayland_options.stderr().contains('-initfd')
+    if have_xwayland_initfd and not xwayland_supports_initfd
       error('XWayland -initfd support requested but not available')
     endif
   endif