[GHC] #12484: Missing pattern synonym signatures gives incorrect fix

[GHC]

#12484: Missing pattern synonym signatures gives incorrect fix
-------------------------------------+-------------------------------------
           Reporter:  alanz          |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Incorrect
  Unknown/Multiple                   |  warning at compile-time
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #11053
Differential Rev(s):                 |         Wiki Page:
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 The following pattern definition

 {{{#!hs
 pattern RP pname help type' <- ParamDesc pname help type' Required
   where RP pname help type' = ParamDesc pname help type' Required
 }}}

 Gives the warning

 {{{
     /....../PluginTypes.hs:248:1: warning: [-Wmissing-signatures]
         Top-level binding with no type signature:
           RP :: ParamName -> ParamHelp -> ParamType -> ParamDescription
 }}}

 The required signature is in fact

 {{{#!hs
 pattern RP :: ParamName -> ParamHelp -> ParamType -> ParamDescription
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12484>
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