you're right, there is a clippy lint for it on a mutex in particular. Tbh I think it might be good to generalize it somehow? Because I think there are other cases it could bite you than just mutexes. But obviously the whole point of doing that in the first place is usually to avoid a must-use warning, so it can't be completely general.

Also, imo, that's probably a clippy lint that should be promoted to a built-in.