No levity-polymorphic arguments

As discussed in our draft paper on levity polymorphism, you cannot have a levity-polymorphic argument. Here is an example:

{-# LANGUAGE RebindableSyntax, TypeInType, ExplicitForAll #-}

module Bug where

import qualified Prelude as P
import GHC.Exts

class Num (a :: TYPE r) where
  (+) :: a -> a -> a
  fromInteger :: P.Integer -> a

foo :: forall (a :: TYPE r). Num a => a
foo = 3 + 4

HEAD panics in kindPrimRep, but the code should be rejected.

Trac metadata

Trac field	Value
Version	8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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