ArrayIndexOutOfBoundsException in ByteStack

[djspiewak]

Look I don't even know…

java.lang.ArrayIndexOutOfBoundsException: Index -268435455 out of bounds for length 402653184
  | => tat cats.effect.ByteStack$.push(ByteStack.scala:59)
	at cats.effect.IOFiber.runLoop(IOFiber.scala:560)
	at cats.effect.IOFiber.autoCedeR(IOFiber.scala:1439)
	at cats.effect.IOFiber.run(IOFiber.scala:119)
	at cats.effect.unsafe.WorkerThread.run(WorkerThread.scala:743)

See DispatcherSpec on the aioobe-reproduction tag at https://github.com/djspiewak/cats-effect

[durban]

I can't reproduce this (I get OutOfMemoryErrors), but that exception more or less seems like what should happen if the size (stack(0)) overflowed from Int.MaxValue to Int.MinValue.

If in push the val c is Int.MinValue, then val s = (c >> 3) + 1 will be -268435455 (the same as in the exception), which is used as an index in line 59.

[armanbilge]

Unless we want to add our own bounds check that gives a more helpful error message, can we close this?

[durban]

We could detect the overflow earlier, by using Math.addExact.