[GHC] #13333: Typeable regression in GHC HEAD

[GHC]

#13333: Typeable regression in GHC HEAD
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  8.1
  checker)                           |
      Resolution:                    |             Keywords:  typeable
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3424
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 >  The end result is that c2 = c1. And then, when c2 gets put in the inert
 set, its kind still mentions unzonked variables. (Even though the
 associated ctPred is just fine.)

 I don't see the problem.  See `Note [Ct/evidence invariant]` in
 `TcRnTypes`.  The types in evidence terms are no zonked, and that should
 not matter one whit.

 Can you explain more precisely what actually goes wrong and why?

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13333#comment:10>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler