[GHC] #7854: Constrained method type accepted in Haskell 98 mode

[GHC]

#7854: Constrained method type accepted in Haskell 98 mode
-------------------------------------+-------------------------------------
        Reporter:  refold            |                   Owner:  thomie
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Compiler (Type    |                 Version:  7.6.3
  checker)                           |                Keywords:  newcomer
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------
Changes (by thomie):

 * owner:   => thomie
 * component:  Compiler => Compiler (Type checker)
 * milestone:   => 7.12.1


Comment:

 More bugs. GHC only rejects the following program when
 `-XConstrainedClassMethods` is turned on. It should however always reject
 it, because `op` doesn't mention any type variables of `Foo`.
 {{{#!hs
 module ShouldFail where
 class Foo a where
   op :: Eq a => Int
 }}}

 I'm working on this.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7854#comment:9>
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