shell: Make sure the shell implementation and protocol versions match

desktop-shell/shell.c

@@ -3421,6 +3421,9 @@ xdg_shell_unversioned_dispatch(const void *implementation,
 
 #define XDG_SERVER_VERSION 1
 
+	static_assert(XDG_SERVER_VERSION == XDG_SHELL_VERSION_CURRENT,
+		      "shell implementation doesn't match protocol version");
+
 	if (args[0].i != XDG_SERVER_VERSION) {
 		wl_resource_post_error(resource,
 				       WL_DISPLAY_ERROR_INVALID_OBJECT,

src/compositor.h

@@ -45,6 +45,10 @@ extern "C" {
 
 #define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
 
+#ifndef static_assert
+#define static_assert(cond, msg)
+#endif
+
 #define container_of(ptr, type, member) ({				\
 	const __typeof__( ((type *)0)->member ) *__mptr = (ptr);	\
 	(type *)( (char *)__mptr - offsetof(type,member) );})