[steveklabnik]

(bounds checks are not removed in release mode, you have to use unsafe to not have the bounds check)

On the /r/rust thread, folks provided examples of why fastmath would produce UB in safe Rust.

[stefs]

ah, i think i meant overflow checks. and thanks for the pointer, i'll have a look.

[steveklabnik]

ah yes, overflow checks are not in release mode today. They may be in the future. And overflow isn't UB, it's two's compliment wrapping.