Undefined behavior isn't a feature. A spec isn't an implementation, either.
All behavior in an implementation can be teased-out if given sufficient time.
> if you were an alien trying to reconstruct it, for example - you'd hit serious problems.
I can't speak to alien minds. Considering the feats of reverse-engineering I've seen in the IT world (software security, semiconductor reverse-engineering) or cryptography (the breaking the Japanese Purple cipher in WWII, for example) I think it's safe to say humans are really, really good at reverse-engineering other human-created systems from close-to-nothing. Starting with documentation would be a step-up.
All behavior in an implementation can be teased-out if given sufficient time.
> if you were an alien trying to reconstruct it, for example - you'd hit serious problems.
I can't speak to alien minds. Considering the feats of reverse-engineering I've seen in the IT world (software security, semiconductor reverse-engineering) or cryptography (the breaking the Japanese Purple cipher in WWII, for example) I think it's safe to say humans are really, really good at reverse-engineering other human-created systems from close-to-nothing. Starting with documentation would be a step-up.