[GHC] #14618: Higher rank typechecking is broken

[GHC]

#14618: Higher rank typechecking is broken
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        Reporter:  mniip             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Richard Eisenberg <rae@…>):

 In [changeset:"722a6584bb338bc77ad978d14113b3b8e6a45cab/ghc" 722a658/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="722a6584bb338bc77ad978d14113b3b8e6a45cab"
 Fix #14618 by applying a subst in deeplyInstantiate

 Previously, we were inexplicably not applying an instantiating
 substitution to arguments in non-prenex types. It's amazing this
 has been around for so long! I guess there aren't a lot of non-prenex
 types around.

 test case: typecheck/should_fail/T14618
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14618#comment:5>
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