Int64.toInteger

GHCi, version 6.8.2: http://www.haskell.org/ghc/  :? for help
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Prelude> 0 == (-1 `Data.Bits.shift` 32 :: Data.Int.Int64)
False
Prelude> 0 == toInteger (-1 `Data.Bits.shift` 32 :: Data.Int.Int64)
True
-- ^^^ BUG

The problem appears to be in the recently changed rts/PrimOps.cmm::int64ToIntegerzh_fast:

   if ( hi != 0 && hi != 0xFFFFFFFF )  { 
      words_needed = 2;
   } else { 
       // minimum is one word
       words_needed = 1;
   }

So, 0xFFFFFFFF00000000 becomes 0.

Trac metadata

Trac field	Value
Version	6.8.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Runtime System
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