[GHC] #15927: Weird interaction between fundeps and overlappable instances

[GHC]

#15927: Weird interaction between fundeps and overlappable instances
-------------------------------------+-------------------------------------
        Reporter:  Darwin226         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.3
       Component:  Compiler          |              Version:  8.6.2
      Resolution:                    |             Keywords:
                                     |  FunctionalDependencies
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  10675, 15632      |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Darwin226):

 Well, since the mtl default is to no only disallow multiple states of the
 same type, but multiple states of ANY type, I wouldn't really call this
 non-scaleable. It's strictly more flexible than mtl.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15927#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler