[GHC] #7643: Kind application error

[GHC]

#7643: Kind application error
----------------------------------------+-----------------------------------
    Reporter:  gmainland                |       Owner:                  
        Type:  bug                      |      Status:  new             
    Priority:  normal                   |   Milestone:                  
   Component:  Compiler (Type checker)  |     Version:  7.6.1           
    Keywords:                           |          Os:  Unknown/Multiple
Architecture:  Unknown/Multiple         |     Failure:  None/Unknown    
  Difficulty:  Unknown                  |    Testcase:                  
   Blockedby:                           |    Blocking:                  
     Related:  #7354                    |  
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Changes (by simonpj):

  * difficulty:  => Unknown


Comment:

 There really is an underlying issue here, about how inference interacts
 with sub-kinding. Sigh.

 It is shown up here becuase you are doing `unsafeCoerce#` on an unlifted
 type, which is a deeply dangerous thing to do.  Better to do it on a
 lifted type.

 Try using this definition of `setIntByteArray#`, which actually uses one
 fewer `unsafeCoerce#` calls:
 {{{
 setIntByteArray# :: MutableByteArray# s -> Int# -> Int# -> Int -> State# s
 -> State# s
 setIntByteArray# arr# i# n# (I# x#) s#  =
     case unsafeCoerce# (internal (setIntArray# arr# i# n# x#)) s# of
       (# s1#, _ #) -> s1#
 }}}
 That makes the attached `Main.hs` compile fine.

 Don't close the ticket though.  The underlying problem (dark corner though
 it is) remains.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7643#comment:2>
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