[GHC] #7368: kindFunResult panic in the

[GHC]

#7368: kindFunResult panic in the
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    Reporter:  ChrisN                   |       Owner:                             
        Type:  bug                      |      Status:  new                        
    Priority:  normal                   |   Milestone:                             
   Component:  Compiler (Type checker)  |     Version:  7.6.1                      
    Keywords:  Kinds, kindfunresult     |          Os:  Unknown/Multiple           
Architecture:  Unknown/Multiple         |     Failure:  Compile-time crash         
  Difficulty:  Unknown                  |    Testcase:  typecheck/should_fail/T7368
   Blockedby:                           |    Blocking:                             
     Related:                           |  
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Comment(by simonpj@…):

 commit be5cc2e33aa8e54299527af9b91e659d54c4cde5
 {{{
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Wed Dec 19 23:49:47 2012 +0000

     Fix TcUnify.matchExpectedTyConApp so that it returns types of
 compatible kinds

     This fixes Trac #7368. The problem was that we were matching
        Bad w ~ f (Bad f)
     where (f :: * -> *).  Thta leads to (w ~ Bad f), which is
     ill-kinded, but matchExpectedTyConApp was returning the (Bad f)
     as the argument type, and that was being used to instanatiate
     w in the data constructor type, which is very bad.

     The code also becomes simpler and easier to understand, which is
     an excellent thing.

  compiler/typecheck/TcUnify.lhs |   81
 ++++++++++++++++++++--------------------
  1 files changed, 40 insertions(+), 41 deletions(-)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7368#comment:6>
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