Sorry avsm. I looked at the patch you linked to and indeed the OCaml developers are all quite enthusiastic about improved error messages. My mistake. The only real blocker is what we both mentioned I believe, that we all want to go slow to make sure the best possible work is merged in.

By the way, the above patch is different from the one that ReasonML uses. Realistically, the work done by the Reason team is more recent and actually shipped with the BuckleScript platform, so now the blocker is, which direction does the OCaml compiler want to go in.