[GHC] #11189: bang pattern parsing inconsistency

[GHC]

#11189: bang pattern parsing inconsistency
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           Reporter:  osa1           |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  7.11
           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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 {{{#!haskell
 -- Works
 f2 (!x, !y) = [x, y]

 -- Parse error on input '!'
 len1 lst =
   case lst of
     [] -> 0
     (!x : !xs) -> 1 + len1 xs

 -- Parse error on input '!'
 len2 [] = 0
 len2 (!x : !xs) = 1 + len xs
 }}}

 Tried with: HEAD, 7.10.2.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11189>
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