Copied from issue Fix #10415: Use `CanEqual` instead of `Eql` for multiversal equality by odersky · Pull Request #10449 · lampepfl/dotty · GitHub since it is SIP material.
Eql is a typeclass used in multi-versal equality to check that regular universal equality == is allowed. I believe that CanEqual is a better name. That way, we do not raise the expectation that this is some sort of equality typeclass.