[GHC] #11540: ghc accepts non-standard type without language extension

[GHC]

#11540: ghc accepts non-standard type without language extension
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           Reporter:  augustss       |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  7.8.4
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Ghc accepts this
 {{{
 f :: Eq a => Eq b => a -> b -> Bool
 f a b = a==a && b==b
 }}}
 The nested contexts should require some language extension.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11540>
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