Some known issues

No support for generics

No support for supertraits

No support for constrained enum-wrapped associated types (i suppose we could "recursively" generate implementations for the new enums)

Naming several trait fn arguments _ will probably break it

Parsing is probably not resilient enough (trailing commas, etc)

Associated type enum generation probably fails if some types are equal.

Need to use absolute paths (::core::convert::From) instead of assuming it's in scope (From)

Failed TryInto conversions for associated type enums could have better errors

No support for renaming crate in Cargo.toml

register doesn't work with implement_for. I can't think of a use case though. Should it?

Currently failing on first error. Better to detect all the errors we can and output them all.

register doesn't validate the trait. Errors only show up when it is implemented.

Need to assert that all enum variant fields are different (at least symbolically) and error otherwise. (Error might be confusing now)