[GHC] #14996: Typed holes are very slow

[GHC]

#14996: Typed holes are very slow
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        Reporter:  simonpj           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  TypedHoles
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by monoidal):

 Another issue is that using a standalone hole gives an error in HEAD (not
 in 8.4):

 {{{
 Prelude> _

 <interactive>:1:1: error:
     GHC internal error: ‘Ghci1.it’ is not in scope during type checking,
 but it passed the renamer
     tcl_env of environment: []
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14996#comment:2>
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