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

[GHC]

#10722: GHC accepts "instance forall b. Blah []"
-------------------------------------+-------------------------------------
        Reporter:  osa1              |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by rwbarton):

 Well I don't care exactly how it is implemented, but logically it is a
 parse error yes. It is the same category of error as
 {{{
 instance Int -> Blah [] where ...
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10722#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler