[GHC] #7090: Panic "mkCoVarLCo" with ConstraintKinds and type-level equality

[GHC]

#7090: Panic "mkCoVarLCo" with ConstraintKinds and type-level equality
---------------------------------+------------------------------------------
    Reporter:  goldfire          |       Owner:  dimitris          
        Type:  bug               |      Status:  new               
    Priority:  normal            |   Milestone:                    
   Component:  Compiler          |     Version:  7.5               
    Keywords:  ConstraintKinds   |          Os:  Unknown/Multiple  
Architecture:  Unknown/Multiple  |     Failure:  Compile-time crash
  Difficulty:  Unknown           |    Testcase:                    
   Blockedby:                    |    Blocking:                    
     Related:                    |  
---------------------------------+------------------------------------------

Comment(by simonpj@…):

 commit d6918e9072e421178d59cd13ee352337a4090c39
 {{{
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Thu Aug 23 11:04:22 2012 +0100

     Don't assume that coercion variables have (~) types

     The constraint solver doesn't zonk the types of coercion variables
     so we can't assume that a coercion variable will have a (~) type.

     Fixes Trac #7090.

  compiler/typecheck/TcEvidence.lhs |   17 ++++++++---------
  1 files changed, 8 insertions(+), 9 deletions(-)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7090#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler