I have a crate with a "perfect" derive macro that generates where clauses from the fields instead of putting them on the generic parameters. It is nice when it works, but yah cyclical trait matching is still a real problem. I wound up needing an attribute to manually override the bounds whenever they blow up: https://docs.rs/inpt/latest/inpt/#bounds
> In the past, we were blocked for technical reasons from expanding implied bounds and supporting perfect derive, but I believe we have resolved those issues. So now we have to think a bit about semver and decide how much explicit we want to be.