libweston-desktop: introduce a deprecated-wl-shell option

This is the first step towards removing wl_shell support.

Add an option so that users can toggle support for the deprecated
wl_shell protocol. This lets users test their clients to make sure
they work fine without wl_shell.

The option is set to false by default.

Signed-off-by: Simon Ser <contact@emersion.fr>

libweston-desktop/libweston-desktop.c

@@ -77,12 +77,21 @@ weston_desktop_create(struct weston_compositor *compositor,
 		return NULL;
 	}
 
+#ifdef HAVE_DEPRECATED_WL_SHELL
+	weston_log("Warning: support for deprecated wl_shell interface is "
+		   "enabled. Please migrate legacy clients to xdg-shell.\n");
 	desktop->wl_shell =
 		weston_desktop_wl_shell_create(desktop, display);
 	if (desktop->wl_shell == NULL) {
 		weston_desktop_destroy(desktop);
 		return NULL;
 	}
+#else
+	weston_log("Note: support for the deprecated wl_shell interface is "
+		   "disabled. If a legacy client still needs it, it can be "
+		   "re-enabled by passing -Ddeprecated-wl-shell=true to Meson "
+		   "when building Weston.\n");
+#endif
 
 	weston_desktop_xwayland_init(desktop);
 

meson.build

@@ -139,6 +139,10 @@ if dep_xkbcommon.version().version_compare('>= 0.5.0')
 	config_h.set('HAVE_XKBCOMMON_COMPOSE', '1')
 endif
 
+if get_option('deprecated-wl-shell')
+	config_h.set('HAVE_DEPRECATED_WL_SHELL', '1')
+endif
+
 dep_wayland_server = dependency('wayland-server', version: '>= 1.18.0')
 dep_wayland_client = dependency('wayland-client', version: '>= 1.18.0')
 dep_pixman = dependency('pixman-1', version: '>= 0.25.2')

meson_options.txt

@@ -138,6 +138,13 @@ option(
 	description: 'Weston desktop shell: default helper client selection'
 )
 
+option(
+	'deprecated-wl-shell',
+	type: 'boolean',
+	value: false,
+	description: 'Enable the deprecated wl_shell protocol'
+)
+
 option(
 	'color-management-lcms',
 	type: 'boolean',