Type operators are broken in GADT-style data definitions

[Rufflewind]

Problem

Type operators are broken in GADT-style data definitions. hindent removes the parentheses from them, breaking the syntax.

• I checked the issue tracker for existing issues about this problem.
• I'm using the latest version of hindent (5.3.1).

Input haskell

{-# LANGUAGE GADTs, TypeOperators #-}

data F where
  (:+) :: Int -> Int -> F

Expected output haskell

{-# LANGUAGE GADTs, TypeOperators #-}

data F where
  (:+) :: Int -> Int -> F

Actual output haskell

{-# LANGUAGE GADTs, TypeOperators #-}

data F where
  :+ :: Int -> Int -> F

[Rufflewind]

Closing as duplicate of #526.