[GHC] #8066: Compiler Panic When Using Instance Derivation With Singletons

[GHC]

#8066: Compiler Panic When Using Instance Derivation With Singletons
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        Reporter:  tvynr               |            Owner:
            Type:  bug                 |           Status:  new
        Priority:  normal              |        Milestone:
       Component:  Compiler            |          Version:  7.6.3
      Resolution:                      |         Keywords:
Operating System:  Unknown/Multiple    |     Architecture:
 Type of failure:  Compile-time crash  |  Unknown/Multiple
       Test Case:                      |       Difficulty:  Unknown
        Blocking:                      |       Blocked By:
                                       |  Related Tickets:
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Comment (by simonpj):

 The HEAD gives
 {{{
 T8066.hs:42:22:
     No instance for (SingE QualForm (KindOf QualForm a))
       arising from the 'deriving' clause of a data type declaration
     Possible fix:
       use a standalone 'deriving instance' declaration,
         so you can specify the instance context yourself
     When deriving the instance for (Show (TVar a))
 }}}
 Does that seem more reasonable?  We've fixed lots of kind-related bugs in
 7.6.

 If the error looks ok, can we close the ticket?

 Simon

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8066#comment:2>
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