meson: Convert xwayland option to feature type

wlroots as a subproject now yields the xwayland meson option to its
parent. We need to match the type for this to work. This also adds
support for auto mode, where xwayland is used if present but no warning
is given otherwise.

.github/workflows/main.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         CC: [ gcc, clang ]
         OS: [ "alpine:edge", "archlinux:base-devel" ]
-        xwayland: [ true, false ]
+        xwayland: [ enabled, disabled ]
     container: ${{ matrix.OS }}
     env:
       CC: ${{ matrix.CC }}
@@ -54,7 +54,7 @@ jobs:
         run: git clone https://gitlab.freedesktop.org/wlroots/wlroots.git subprojects/wlroots -b 0.16.0
       - name: Check for formatting changes
         run: |
-          meson build-clang-format -Dxwayland=true
+          meson build-clang-format -Dxwayland=enabled
           ninja -C build-clang-format clang-format-check
 
   scan-build:
@@ -73,5 +73,5 @@ jobs:
         run: git clone https://gitlab.freedesktop.org/wlroots/wlroots.git subprojects/wlroots -b 0.16.0
       - name: Run scan-build
         run: |
-          meson build-scan-build -Dxwayland=true
+          meson build-scan-build -Dxwayland=enabled
           ninja -C build-scan-build scan-build

meson.build

@@ -64,9 +64,9 @@ server_protos = declare_dependency(
   sources: server_protos_headers,
 )
 
-if get_option('xwayland')
+if not get_option('xwayland').disabled()
   wlroots_has_xwayland = wlroots.get_variable(pkgconfig: 'have_xwayland', internal: 'have_xwayland') == 'true'
-  if not wlroots_has_xwayland
+  if get_option('xwayland').enabled() and not wlroots_has_xwayland
     error('Cannot build Cage with XWayland support: wlroots has been built without it')
   endif
   have_xwayland = true

meson_options.txt

@@ -1,2 +1,2 @@
 option('man-pages', type: 'feature', value: 'auto', description: 'Generate and install man pages')
-option('xwayland', type: 'boolean', value: false, description: 'Enable support for X11 applications')
+option('xwayland', type: 'feature', value: 'auto', description: 'Enable support for X11 applications')