[GHC] #15761: pprFamInstLHS drops parentheses

[GHC]

#15761: pprFamInstLHS drops parentheses
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           Reporter:  goldfire       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.6.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 If I say

 {{{#!hs
 data family (a + b) c d

 data instance (Int + Bool) Double = Float
 }}}

 GHC says

 {{{
     • Expecting one more argument to ‘Int + Bool Double’
       Expected a type, but ‘Int + Bool Double’ has kind ‘* -> *’
     • In the data instance declaration for ‘+’
 }}}

 Note the missing parens in the first line of the error.

 Will fix shortly.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15761>
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