[eddyb]

> * It technically violates Rust's rules against private symbols in the public API, so a future version of rustc might deprecate or remove that functionality.

It's public though, just not externally reachable, the private module doesn't make the trait private.

For example, if you wanted to, you could reexport the trait in the parent module (and I guess the drawback with the "sealed" pattern is accidentally doing that when it would be unsound do because of how you relied on it being "sealed", in unsafe code).

I don't think I've heard anything about plans to restrict anything based on reachability, and it would be massively backwards-incompatible so I doubt it would even be considered for an edition.