[GHC] #7848: Missing parentheses and backticks

[GHC]

#7848: Missing parentheses and backticks
----------------------------------------------+-----------------------------
Reporter:  monoidal                           |          Owner:                  
    Type:  bug                                |         Status:  new             
Priority:  normal                             |      Component:  Compiler        
 Version:  7.6.2                              |       Keywords:                  
      Os:  Unknown/Multiple                   |   Architecture:  Unknown/Multiple
 Failure:  Incorrect warning at compile-time  |      Blockedby:                  
Blocking:                                     |        Related:                  
----------------------------------------------+-----------------------------
 In several cases, GHC does not output parentheses or backticks in error
 messages. For example, compiling this contrived file

 {{{
 data A = (:&&) Int Int | A Int Int

 x (+) ((&)@z) ((:&&) a b) (c :&& d) (e `A` f) (A g h) = y
   where infixl 3 `y`
         y _ = (&)
         {-# INLINE (&) #-}
         {-# SPECIALIZE (&) :: a #-}
         (&) = x
 }}}

 gives an error message containing:

 {{{
 x + (&@z) (:&& a b) (c :&& d) (e A f) (A g h)
   = y
   where
       infixl 3 y
       y _ = (&)
       {-# INLINE & #-}
       {-# SPECIALIZE & :: a #-}
 }}}

 Attached patch fixes this issue in several places.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7848>
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