[GHC] #9306: Crash when shifting Integers too much

[GHC]

#9306: Crash when shifting Integers too much
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        Reporter:  dfeuer            |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  libraries/base    |          Version:  7.8.3
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  Runtime crash     |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by hvr):

 The problem here is that the shift amount is of type `Int`, so
 `fromIntegral (maxBound::Int) + 1` is actually `minBound`, so the code

 {{{#!hs
 okay = 1000 `shiftR` (fromIntegral (maxBound::Int) + 1) :: Integer
 tooFar = 1 `shiftR` (fromIntegral (maxBound::Int) + 2) :: Integer
 }}}

 is the same as

 {{{#!hs
 okay = 1000 `shiftR` minBound :: Integer
 tooFar = 1 `shiftR` (minBound + 1) :: Integer
 }}}

 And both should have overflowed, as you are effectively requesting a left-
 shift by a *huge* amount

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9306#comment:1>
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