Panic - Messed up size accounting

[weaversa]

I ran across this panic today. I'm sorry I don't have a ready example.

Revision: UNKNOWN
Branch: UNKNOWN
Location: lookupSeqMap
Message: Messed up size accounting
        Nat 2
         2
CallStack (from HasCallStack):
  panic, called at src/Cryptol/Utils/Panic.hs:21:9 in cryptol-3.0.0.99-inplace:Cryptol.Utils.Panic
  panic, called at src/Cryptol/Backend/SeqMap.hs:100:28 in cryptol-3.0.0.99-inplace:Cryptol.Backend.SeqMap

[weaversa]

The code that caused this worked w/ 2.13, but panics on 3.0

[yav]

I suspect the issue is here:

cryptol/src/Cryptol/Backend/SeqMap.hs

Line 100 in 383a597

(\j -> panic "lookupSeqMap" ["Messed up size accounting", show sz, show j])))

We should only panic if the index is in bounds. Otherwise, we should throw an exception that the index is out of bounds.

[yav]

Another issue with this code is that it has a race condition if it is used with parallel evalution (e.g., parmap)