[vinkelhake]

With clang 3.5 on x86-64 Linux I also get an infinite loop.

Compiled with GCC, it doesn't go into an infinite loop. Zed seems to think this makes your example a "fail". This is curious since the whole quibble is about functions that work in some context but fail when brought into a different context.

Edit: FWIW, safercopy also has undefined behavior when from_length and to_length are larger than MAX_INT.

[mikeash]

It's only curious if you think Zed is honestly trying to figure out the truth, rather that "prove" he's right. That assumption is clearly shown to be wrong by this comment thread.