[GHC] #9190: Iface type variable out of scope: s

[GHC]

#9190: Iface type variable out of scope:  s
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        Reporter:  nomeata           |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.9
      Resolution:                    |         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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Comment (by nomeata):

 If the above interface output is indeed a symptom of something being
 wrong, then this module (extracted from math-functions) suffices to
 reproduce it (still needs vector-th-unbox, slowly working towards less
 dependencies). I cannot trigger the the actual error with that, though.

 {{{
 {-# LANGUAGE MultiParamTypeClasses, TemplateHaskell, TypeFamilies #-}
 module T9190a where

 import Data.Vector.Unboxed.Deriving (derivingUnbox)

 data KBNSum = KBNSum Double Double

 derivingUnbox "KBNSum"
     [t| KBNSum -> (Double, Double) |]
     [| \ (KBNSum a b) -> (a, b) |]
     [| \ (a, b) -> KBNSum a b |]
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9190#comment:7>
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