[GHC] #9889: Pattern synonym does not work in top-level pattern bind

[GHC]

#9889: Pattern synonym does not work in top-level pattern bind
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              Reporter:  goldfire    |            Owner:  cactus
                  Type:  bug         |           Status:  patch
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.9
  (Type checker)                     |         Keywords:  PatternSynonyms
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:  GHC         |  Related Tickets:
  rejects valid program              |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Changes (by cactus):

 * status:  new => patch


Comment:

 I've pushed a proposed fix for this to the `wip/T9889` branch, but it
 might be a bit of a sensitive change, since it requires introducing
 pattern synonym names in the renamer in a separate pass between renaming
 `TyClDecl`s and `HsValBind`s. Simon, please review.

 {{{
 commit e5f429cbc02df745df1517d53c8ca170de41757b
 Author: Dr. ERDI Gergo <gergo at erdi.hu>
 Date:   Wed Dec 17 22:09:06 2014 +0800

     Pattern synonym names need to be in scope before renaming bindings
 (#9889)

 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9889#comment:3>
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