[GHC] #13293: ConstrainedClassMethods makes GeneralizedNewtypeDeriving fail

[GHC]

#13293: ConstrainedClassMethods makes GeneralizedNewtypeDeriving fail
-------------------------------------+-------------------------------------
        Reporter:  j.waldmann        |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2
      Resolution:  duplicate         |             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:                    |
-------------------------------------+-------------------------------------
Changes (by rwbarton):

 * status:  new => closed
 * resolution:   => duplicate


Comment:

 This is a duplicate of #12768; see there for much discussion.

 The short version is: while it would arguably be correct to be able to use
 GND in this particular case of a class with a method which is constrained
 by the same class, it's not useful enough to add special logic to GHC to
 handle it.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13293#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler