video: simplify window-type check in SDL_CreateWindow

src/video/SDL_video.c

@@ -1597,7 +1597,7 @@ SDL_Window *
 SDL_CreateWindow(const char *title, int x, int y, int w, int h, Uint32 flags)
 {
     SDL_Window *window;
-    Uint32 graphics_flags = flags & (SDL_WINDOW_OPENGL | SDL_WINDOW_METAL | SDL_WINDOW_VULKAN);
+    Uint32 type_flags, graphics_flags = flags & (SDL_WINDOW_OPENGL | SDL_WINDOW_METAL | SDL_WINDOW_VULKAN);
 
     if (!_this) {
         /* Initialize the video system if needed */
@@ -1606,7 +1606,9 @@ SDL_CreateWindow(const char *title, int x, int y, int w, int h, Uint32 flags)
         }
     }
 
-    if ((((flags & SDL_WINDOW_UTILITY) != 0) + ((flags & SDL_WINDOW_TOOLTIP) != 0) + ((flags & SDL_WINDOW_POPUP_MENU) != 0)) > 1) {
+    /* ensure no more than one of these flags is set */
+    type_flags = flags & (SDL_WINDOW_UTILITY | SDL_WINDOW_TOOLTIP | SDL_WINDOW_POPUP_MENU);
+    if ((type_flags & (type_flags - 1)) != 0) {
         SDL_SetError("Conflicting window flags specified");
         return NULL;
     }