[GHC] #7453: unsafe coerce without extensions

[GHC]

#7453: unsafe coerce without extensions
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Reporter:  guest                        |          Owner:                         
    Type:  bug                          |         Status:  new                    
Priority:  normal                       |      Component:  Compiler (Type checker)
 Version:  7.6.1                        |       Keywords:                         
      Os:  Unknown/Multiple             |   Architecture:  Unknown/Multiple       
 Failure:  GHC accepts invalid program  |      Blockedby:                         
Blocking:                               |        Related:                         
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Comment(by ion1):

 This has some security implications as well.

 {{{
 % mueval -e 'let unsafeCoerce v = z where z :: v; z = v where aux = const
 v in (unsafeCoerce (putStrLn "evil IO action") :: () -> ()) ()'
 evil IO action
 ()
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7453#comment:7>
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