GHC panic with visible kind applications

Using the https://phabricator.haskell.org/D5229 diff

This is fine

{-# Language RankNTypes       #-}
{-# Language TypeApplications #-}
{-# Language PolyKinds        #-}
{-# Language GADTs            #-}

import Data.Kind

data
  App :: forall (f :: Type -> Type). Type -> Type
  where
  MkApp :: f a -> App @f a

Kind polymorphic is fine

{-# Language RankNTypes       #-}
{-# Language TypeApplications #-}
{-# Language PolyKinds        #-}
{-# Language GADTs            #-}

import Data.Kind

data
  App :: forall k (f :: k -> Type). k -> Type
  where
  MkApp :: f a -> App @k @(f :: k -> Type) (a :: k)

But offing the visibility of k fails

{-# Language RankNTypes       #-}
{-# Language TypeApplications #-}
{-# Language PolyKinds        #-}
{-# Language GADTs            #-}

import Data.Kind

data
  App :: forall (f :: k -> Type). k -> Type
  where
  MkApp :: f a -> App @(f :: k -> Type) (a :: k)

{-# Language RankNTypes       #-}
{-# Language TypeApplications #-}
{-# Language PolyKinds        #-}
{-# Language GADTs            #-}

import Data.Kind

data
  App :: forall (f :: k -> Type). k -> Type
  where
  MkApp :: f a -> App @f a

$ ghci -ignore-dot-ghci 581_bug.hs
GHCi, version 8.7.20181017: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( 581_bug.hs, interpreted )
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 8.7.20181017 for x86_64-unknown-linux):
        ASSERT failed!
  2
  1
  f_a1yB[tau:1]
  f_a1yx[sk:1]
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable
        pprPanic, called at compiler/utils/Outputable.hs:1219:5 in ghc:Outputable
        assertPprPanic, called at compiler/typecheck/TcMType.hs:778:54 in ghc:TcMType

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

> 

Trac metadata

Trac field	Value
Version	8.6.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	mnguyen
Operating system
Architecture