[GHC] #10571: GHC 7.10.1 segfaults when shiftL-ing Integers by negative amounts

[GHC]

#10571: GHC 7.10.1 segfaults when shiftL-ing Integers by negative amounts
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        Reporter:  anders_           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  MacOS X           |            Architecture:  x86_64
 Type of failure:  Runtime crash     |  (amd64)
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Changes (by rwbarton):

 * cc: hvr (added)
 * priority:  normal => high


Comment:

 The documentation for `shiftL` does say "the specified number of bits
 (which must be non-negative)", so the first case might be okay, but
 crashing is too much.

 The whole `shift`/`shiftL`/`shiftR` thing seems a little dubious to me in
 general, but surely for Integer we should test the sign of the shift in
 `shiftL`/`shiftR` and produce the expected result.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10571#comment:1>
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