[GHC] #9922: Partial type signatures + extensions panic

[GHC]

#9922: Partial type signatures + extensions panic
-------------------------------------+-------------------------------------
       Reporter:  monoidal           |                   Owner:
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  Compiler (Type     |                 Version:  7.9
  checker)                           |        Operating System:
       Keywords:                     |  Unknown/Multiple
   Architecture:  Unknown/Multiple   |         Type of failure:  Compile-
     Difficulty:  Unknown            |  time crash
     Blocked By:                     |               Test Case:
Related Tickets:                     |                Blocking:
                                     |  Differential Revisions:
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 Partial type signatures combined with the following GHC extensions cause a
 panic:

 {{{#!hs
 class C a where default f :: _       -- DefaultSignatures

 instance Num Bool where negate :: _  -- InstanceSigs

 deriving instance _                  -- StandaloneDeriving
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9922>
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