We are preparing the compiler for a new trait solver, which will allow us to close a whole group of soundness bugs that have been plagueing us for years. Unfortunately this also means that a specific kind of overlapping trait impls that your crate uses is going to be rejected. Since your crate was the only crate on all of crates.io that we found to be using this pattern, we're likely going to be moving forward with doing this change. It won't break your crate for a while yet, but your crate will emit a lint that will at some point become a hard error.

See https://crater-reports.s3.amazonaws.com/pr-114023-1/try%2308441e81149850f42fc7dca57e00378ff0794572/reg/interval-map-0.1.1/log.txt for the new future incompat lint that will be emitted soon

See rust-lang/rust#114023 for the change itself and links to the reasoning for it.