[GHC] #8616: "Internal error" with ScopedTypeVariables and kind variables

16 Dec 2013

      #8616: "Internal error" with ScopedTypeVariables and kind variables
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       Reporter:  goldfire          |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Compiler          |           Version:  7.7
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 When I try to compile the following nonsense with HEAD

 {{{
 {-# LANGUAGE PolyKinds, RankNTypes, ScopedTypeVariables #-}

 import Data.Proxy
 import GHC.Exts

 withSomeSing :: forall (kproxy :: k). Proxy kproxy
 withSomeSing = undefined :: (Any :: k)
 }}}

 I get this

 {{{
     GHC internal error: ‛k’ is not in scope during type checking, but it
 passed the renamer
     tcl_env of environment: [(a4XG, Type variable ‛kproxy’ = kproxy),
                              (r4MW,
                               Identifier[withSomeSing::forall (k :: BOX)
 (kproxy :: k).
                                                        Proxy k kproxy,
 <NotTopLevel>])]
     In the kind ‛k’
     In an expression type signature: (Any :: k)
     In the expression: undefined :: (Any :: k)
 }}}

 The code is very bogus, but so is GHC's response.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8616
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