[GHC] #10722: GHC accepts "instance forall b. Blah []"

[GHC]

#10722: GHC accepts "instance forall b. Blah []"
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        Reporter:  osa1              |                   Owner:
            Type:  bug               |                  Status:  closed
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:  invalid           |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"d7ced09a0a8d9e0f3c6631e2814078145036c90a/ghc"
 d7ced09a/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d7ced09a0a8d9e0f3c6631e2814078145036c90a"
 Minor improvement to user guide

 Specify that the type variables for a class/instance decl scope
 over the body even without a 'forall'.

 Provoked by Trac #10722.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10722#comment:6>
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