Naked functions do not require unsafety

[nagisa]

RFC states that naked functions must either not contain any “safe” blocks or be unsafe themselves. Currently, code like

#![feature(asm, naked_functions)]

#[naked]
extern "win64" fn naked(x: u32) -> u32 {
    x + 1
}

is accepted.

[nagisa]

cc #32408

[steveklabnik]

Triage: still reproduces today

[npmccallum]

@nagisa @steveklabnik I propose we reject this bug in light of the Constrained Naked RFC. There is nothing which prevents a naked function from being safe.