Incorrect failure of type-level skolem escape check
From D1739.
When you say
undefined :: forall (v :: Levity). forall (a :: TYPE v). (?callStack :: CallStack) => a
you get a skolem escape failure because GHC things that the kind of (?callStack :: CallStack) => a is TYPE v. It should be *.
I will fix.
Edited by Ben Gamari