[GHC] #8841: PatternSynonyms error gives wrong source locations

[GHC]

#8841: PatternSynonyms error gives wrong source locations
-------------------------+-------------------------------------------------
       Reporter:         |             Owner:
  Iceland_jack           |            Status:  new
           Type:  bug    |         Milestone:  7.8.1
       Priority:  low    |           Version:  7.8.1-rc2
      Component:         |  Operating System:  Linux
  Compiler               |   Type of failure:  Incorrect warning at
       Keywords:         |  compile-time
  PatternSynonyms        |         Test Case:
   Architecture:  x86    |          Blocking:
     Difficulty:         |
  Unknown                |
     Blocked By:         |
Related Tickets:         |
-------------------------+-------------------------------------------------
 Using an example from the
 [http://www.haskell.org/ghc/docs/7.8.1-rc1/html/users_guide/syntax-
 extns.html GHC user's guide] but omitting the argument to `Maybe`

 {{{
 {-# LANGUAGE PatternSynonyms #-}

 data Type = App String [Type]

 pattern Maybe = App "Maybe" [t]
 }}}

 gives the following error without the correct source locations

 {{{
 ghci> :load /tmp/failure.hs
 [1 of 1] Compiling Main             ( /tmp/failure.hs, interpreted )

 /tmp/failure.hs:1:1:
     Right-hand side of bidirectional pattern synonym cannot be used as an
 expression
       App "Maybe" [t]
 Failed, modules loaded: none.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8841>
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