-{- No longer needed: evidence is in the EvBinds
- | isTcTyVar orig && isMetaTyVar orig
- = do { meta_details <- wrapTcS $ TcM.readWantedCoVar orig
- ; case meta_details of
- Flexi -> return Nothing
- Indirect tyco -> chase_ev assocs trg curr_grav
- (orig:visited) (EvCoercion tyco)
- }
--}
- | otherwise = return Nothing