'Getting info on a Kind inference bug in GHC

Edward Kmett reported a bug in kind inference which is pretty annoying for his category library some time ago.

I can't tell if this has been solved or not in some later version of GHC. It seems to be present in 8.10.7 and 9.0.2.

{-# LANGUAGE PolyKinds #-}
class D a => C (f :: k) a
class C () a => D a

data W f (a :: k) where
  MkW :: W Maybe Int -> W f a

How to get information on this (like : will it be solved or not) ?

haskell

Sources

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