[GHC] #9167: Associated type is accepted even without mentioning class parameters

[GHC]

#9167: Associated type is accepted even without mentioning class parameters
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        Reporter:  goldfire                      |            Owner:
            Type:  bug                           |           Status:
        Priority:  low                           |  closed
       Component:  Compiler                      |        Milestone:
      Resolution:  fixed                         |          Version:  7.8.2
Operating System:  Unknown/Multiple              |         Keywords:
 Type of failure:  None/Unknown                  |     Architecture:
       Test Case:                                |  Unknown/Multiple
  indexed_types/should_fail/T9167                |       Difficulty:
        Blocking:                                |  Unknown
                                                 |       Blocked By:
                                                 |  Related Tickets:
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Comment (by archblob):

 The error message now says
 {{{
 The associated type ‘F’
     mentions none of the type variables of the class ‘C k a’
     In the class declaration for ‘C’
 }}}
 but
 {{{#!haskell
 class C (a :: k) where
   type F (b :: k)
 }}}
 is accepted although none of the class type variables are mentioned in the
 definition for `F` . If this is the intended behavior maybe the error
 message should say type or kind variables.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9167#comment:4>
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