The Hashtable Problem: A Litmus Test for External Impl Proposals

benschulz: > This is only true for proposals that intend to allow overlapping implementations. Right. The main problem there is that disallowing them would make most added trait implementations a breaking change for any library crates. This would not be (much of) an issue for executable-only crates, which would already cover a lot of ground in practice. There may be some ecosystem tradeoffs in terms of fewer stand-alone binaries being made also usable as libraries.