anymap stopping being compilable in future?

[vi]

rust-lang/rust#51443

warning: the trait `any::CloneToAny` cannot be made into an object
  --> /mnt/src/git/anymap/src/any.rs:15:8
   |
15 |     fn clone_to_any_send(&self) -> Box<CloneAny + Send> where Self: Send;
   |        ^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(where_clauses_object_safety)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #51443 <https://github.com/rust-lang/rust/issues/51443>
   = note: method `clone_to_any_send` references the `Self` type in where clauses

Does anymap rely on a trick deemed unsound?

[vi]

Duplicate of #31.