Incorrect parenthesization of type in error message

If you compile this program:

{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE GADTs #-}

import GHC.Exts (Constraint)

data Dict a where
  Dict :: a => Dict a

foo :: Dict (Int ~ Int) => Int
foo = undefined

In GHC 8.0.1, 8.0.2, 8.2.1, or HEAD, it will give this error message:

GHCi, version 8.3.20170509: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /home/rgscott/.ghci
[1 of 1] Compiling Main             ( Bug2.hs, interpreted )

Bug2.hs:9:8: error:
    • Expected a constraint, but ‘Dict Int ~ Int’ has kind ‘*’
    • In the type signature: foo :: Dict (Int ~ Int) => Int
  |
9 | foo :: Dict (Int ~ Int) => Int
  |        ^^^^^^^^^^^^^^^^

But Dict Int ~ Int is not parenthesized correctly!

This is a regression, as GHC 7.10.3 and earlier parenthesize it correctly:

GHCi, version 7.10.3: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( Bug2.hs, interpreted )

Bug2.hs:9:8:
    Expected a constraint, but ‘Dict (Int ~ Int)’ has kind ‘*’
    In the type signature for ‘foo’: foo :: Dict (Int ~ Int) => Int

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
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