I remember using g++ on Windows (via cygwin or something) and writing a function that was supposed to return a Boolean, but sometimes didn't return any value at

I remember using g++ on Windows (via cygwin or something) and writing a function that was supposed to return a Boolean, but sometimes didn't return any value at all. Real spaghetti, in university, no less. Throwaway code, in my defense. Turns out the code not only escaped detection, but the resulting binary always returned the same Boolean value when the code path where no return should be made were run. Don't think I've seen one since, though I have found a nasty footgun in Scala where if you do a fold of a parallel collection, you can give the fold a starting value, which will be supplied to all the executing threads. The result therefore depends on how many cores you have running. Sadly I suspect that one's in spec.