Safer languages manage similar optimizations without having to rely on UB.

Well, yes, safer languages prevent pointer forging statically, so provenance is trivially enforced.

And I believe that provenance is an issue in unsafe rust.

	▲	tialaramex 4 days ago \| parent [-]
		Unlike C++ and (until Martin's work is moved to the actual language ISO document rather than separate) C the Rust language actually has a definition for how provenance is supposed to work. https://doc.rust-lang.org/std/ptr/index.html#provenance The definition isn't deemed complete because of aliasing. AIUI The definition we have is adequate if you're OK with treating all edge cases for "Is this an alias?" as "Yes" but eventually Rust will also need to carefully nail down all those edge cases so that you can tread closer without falling off.