Pretty-printer butchers function arrow fixity on GHC HEAD

This code:

{-# LANGUAGE TemplateHaskell #-}
{-# OPTIONS_GHC -ddump-splices #-}
module Bug where

$([d| f :: Either Int (Int -> Int)
      f = undefined
    |])

Pretty-prints incorrectly on GHC HEAD:

$ /opt/ghc/head/bin/ghci Bug.hs
GHCi, version 8.3.20170706: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /home/rgscott/.ghci
[1 of 1] Compiling Bug              ( Bug.hs, interpreted )
Bug.hs:(5,3)-(7,6): Splicing declarations
    [d| f_a1sG :: Either Int (Int -> Int)
        f_a1sG = undefined |]
  ======>
    f_a4bj :: Either Int Int -> Int
    f_a4bj = undefined

But not on GHC 8.2.1-rc3:

$ /opt/ghc/8.2.1/bin/ghci Bug.hs
GHCi, version 8.2.0.20170704: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /home/rgscott/.ghci
[1 of 1] Compiling Bug              ( Bug.hs, interpreted )
Bug.hs:(5,3)-(7,6): Splicing declarations
    [d| f_a1su :: Either Int (Int -> Int)
        f_a1su = undefined |]
  ======>
    f_a4aV :: Either Int (Int -> Int)
    f_a4aV = undefined

Trac metadata

Trac field	Value
Version	8.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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