[GHC] #12716: Suggest ScopedTypeVariables when type variable not in scope

[GHC]

#12716: Suggest ScopedTypeVariables when type variable not in scope
-------------------------------------+-------------------------------------
        Reporter:  ezyang            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by thomie):

 Duplicate of #9244 (and #1316, #3691, #11438, #10581, #11539, ...).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12716#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler