[GHC] #9035: ghci sometimes displays Word32 as Word64

[GHC]

#9035: ghci sometimes displays Word32 as Word64
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        Reporter:  MikeIzbicki                  |            Owner:
            Type:  bug                          |           Status:  closed
        Priority:  normal                       |        Milestone:
       Component:  GHCi                         |          Version:  7.8.2
      Resolution:  invalid                      |         Keywords:
Operating System:  Linux                        |     Architecture:  x86_64
 Type of failure:  Incorrect result at runtime  |  (amd64)
       Test Case:                               |       Difficulty:
        Blocking:                               |  Unknown
                                                |       Blocked By:
                                                |  Related Tickets:
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Comment (by MikeIzbicki):

 Replying to [comment:2 igloo]:
 > This use of `unsafeCoerce` is not safe: See
 [http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.7.0.0
 /Unsafe-Coerce.html this] which links to
 [http://www.haskell.org/ghc/docs/latest/html/libraries/ghc-prim-0.3.1.0
 /GHC-Prim.html#v:unsafeCoerce-35- here] for more details.

 I don't understand why it is incorrect.  Is it because the float is boxed?
 We can easily change the code to:

 {{{
 float2word32 :: Float -> Word32
 float2word32 (F# f#) = W32# (unsafeCoerce# f#)
 }}}

 Now, we are casting between two unboxed types of the same size, which is
 explicitly allowed.  The results, however, are exactly the same as before.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9035#comment:3>
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