Patched to compile on C89 compilers.

src/video/wayland/SDL_waylandevents.c

@@ -293,13 +293,14 @@ keyboard_handle_enter(void *data, struct wl_keyboard *keyboard,
                       struct wl_array *keys)
 {
     struct SDL_WaylandInput *input = data;
+    SDL_WindowData *window;
 
     if (!surface) {
         /* enter event for a window we've just destroyed */
         return;
     }
  
-    SDL_WindowData *window = wl_surface_get_user_data(surface);
+    window = wl_surface_get_user_data(surface);
 
     input->keyboard_focus = window;
     window->keyboard_device = input;