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Segfault when using enumFromTo with maxBound as upper bound #188
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This only happens with optimizations enabled for me. Looking at the core it seems like what's happening is the counter from 0 to 255 is being incremented by one and then being compared with
<=to 255. I think that the counter is overflowing back to 0 and so the code writes past the end of the allocated vector (which I checked is correctly allocated to 256 elements).I also get a segmentation fault from this simpler code:
main :: IO () main = do let t = V.enumFromTo 255 255 :: V.Vector Word8 t `seq` putStrLn "Thawing succeeded"
- changed the title
[-]Segfault when thawing enumFromTo of Word8's[/-][+]Segfault when using enumFromTo with maxBound as upper bound[/+]on Nov 30, 2017 I updated the ticket title because this isn't specific to thaw, or to Word8, it is reproducible with Word16, Word32, etc as long as the upper bound is set to
maxBoundI have also updated the code.
Do we know what's broken? Tracing along the
enumFromToimplementation, I get to a corresponding function on (monadic) bundles. But that just callsfromList [x .. y].Is it
unstreamthat's broken?The bug is in this code: https://github.com/haskell/vector/blob/master/Data/Vector/Fusion/Bundle/Monadic.hs#L758-L767
Specifically the
+1on this line is overflowing.https://github.com/haskell/vector/blob/master/Data/Vector/Fusion/Bundle/Monadic.hs#L766
The bug is also present in the specialized code for
Inthttps://github.com/haskell/vector/blob/master/Data/Vector/Fusion/Bundle/Monadic.hs#L809-L824
booo, this needs to be fixed, adding to action list :)
brr, this has been languishing for too long
- added a commit that references this issue
on Jan 31, 2020 this should be resolved in master now
I get a segfault when running the following code:
I now use
enumFromNas a workaround, that works.This happens with
vector-0.12.0.1from hackage.