Keep in mind it's UB to be:

> Executing code compiled with target features that the current thread of execution does not support

I.e. calling AVX512 on Neon architecture.

You need to wrap it in target attributes to even dream of it being safe.

This particular UB is not one of the subtle cases. You will almost certainly get illegal instruction signals if you mess this up.

Is rust UB different from C UB? C UB must be avoided at all costs even if you think you know the actual behavior.

It is not.