[GHC] #9732: Pattern synonyms and unboxed values

[GHC]

#9732: Pattern synonyms and unboxed values
-------------------------------------+-------------------------------------
              Reporter:  monoidal    |            Owner:  cactus
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.8.3
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:  Compile-    |       Blocked By:
  time crash                         |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------

Comment (by cactus):

 As for the unidirectional case, I was accidentally looking at the
 simplified output instead of just the desugared one. So with this code:

 {{{
 {-# LANGUAGE PatternSynonyms, MagicHash #-}
 pattern PAT <- 0#

 f PAT = 42#
 }}}

 the Core generated for `f` is:

 {{{
 Main.f :: GHC.Prim.Int# -> GHC.Prim.Int#
 [LclIdX, Str=DmdType]
 Main.f =
   \ (ds_dpR :: GHC.Prim.Int#) ->
     break<2>()
     case (\ _ [Occ=Dead, OS=OneShot] ->
             Control.Exception.Base.patError
               @ GHC.Prim.Int# "T9732.hs:7:1-11|function f"#)
            GHC.Prim.void#
     of wild_00 { __DEFAULT ->
     (case break<1>() 42 of wild_X4 { __DEFAULT ->
      Main.$mPAT @ GHC.Prim.Int# ds_dpR wild_X4
      })
       wild_00
     }
 }}}

 which is close enough: it would be correct if only `wild_00` wasn't
 floated out...

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9732#comment:9>
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