[GHC] #11136: Associated type family: panic due to mismatch in arity of default instances

[GHC]

#11136: Associated type family: panic due to mismatch in arity of default instances
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        Reporter:  airini            |                Owner:  simonpj
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.10.2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"49aae125686db914a73199d4f789370313892f8f/ghc" 49aae12/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="49aae125686db914a73199d4f789370313892f8f"
 Check arity on default decl for assoc types

 Fixes Trac #11136.  We should check arity before
 doing tcTyClTyVars, because the latter crahes if
 the arity isn't right.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11136#comment:2>
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