[GHC] #8359: ConstraintKinds require UndecidableInstances when it doesn't need it

[GHC]

#8359: ConstraintKinds require UndecidableInstances when it doesn't need it
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        Reporter:  thomaseding                |            Owner:  simonpj
            Type:  bug                        |           Status:  new
        Priority:  normal                     |        Milestone:
       Component:  Compiler                   |          Version:  7.4.2
      Resolution:                             |         Keywords:
Operating System:  Unknown/Multiple           |     Architecture:
 Type of failure:  GHC rejects valid program  |  Unknown/Multiple
       Test Case:                             |       Difficulty:  Unknown
        Blocking:                             |       Blocked By:
                                              |  Related Tickets:
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Comment (by unknown <simonpj@?>):

 In [changeset:4407614cb19a65ddb2f9ede4778a0b47396f8ec9/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="4407614cb19a65ddb2f9ede4778a0b47396f8ec9"
 Look inside tuple predicates when checking instance declaration contexts

 This fixes Trac #8359
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8359#comment:3>
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