Now-safe `cpuid` triggers `unused_unsafe`

[mkroening]

@joshtriplett wrote in rust-lang/rust#146560 (comment):

That said, counterproposal: rather than a target feature, can we transition to cpuid being universally safe (using the mechanisms we normally use to move something from unsafe to safe without provoking widespread warnings about unused unsafe)?

cpuid currently triggers unused_unsafe (see rust-osdev/x86_64#575). Is this intentional?

[RalfJung]

Thanks for reporting this! This seems like an oversight indeed. Cc @sayantn

That said, I am honestly not entirely sure which mechanisms Josh is referring to here...

[tgross35]

I think the unused_unsafe is actually useful here - isn't it useful to know that those functions can get rid of their only unsafe block?

[mkroening]

Yes, that's useful. Though, it requires allowing the lint on crates that support older rust versions where unsafe is needed. For me it is fine either way. I just wanted to make sure this is not an oversight.