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A-const-evalArea: Constant evaluation, covers all const contexts (static, const fn, ...)Area: Constant evaluation, covers all const contexts (static, const fn, ...)E-easyCall for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue.Call for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue.E-needs-testCall for participation: An issue has been fixed and does not reproduce, but no test has been added.Call for participation: An issue has been fixed and does not reproduce, but no test has been added.
Description
Some people were of the opinion that this shouldn't work, but it currently does. playground:
#![feature(atomic_integers, const_fn)]
use std::sync::atomic::AtomicUsize;
use std::sync::atomic::Ordering;
const unsafe fn transmute(x: *mut u8) -> usize {
union T {
a: *mut u8,
b: usize
}
T { a: x }.b
}
const BAR: *mut u8 = ((|| 3) as fn() -> i32) as *mut u8;
const FOO: AtomicUsize = AtomicUsize::new(unsafe { transmute(BAR) });
// static FOO: AtomicUsize = AtomicUsize::new(unsafe { transmute(BAR) }); // ALSO OK
// const BAZ: AtomicUsize = AtomicUsize::new(BAR as usize); ERRORs
fn main() {
let l = FOO.load(Ordering::Relaxed);
let l: fn() -> i32 = unsafe { std::mem::transmute(l) };
assert_eq!(l(), 3);
}
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A-const-evalArea: Constant evaluation, covers all const contexts (static, const fn, ...)Area: Constant evaluation, covers all const contexts (static, const fn, ...)E-easyCall for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue.Call for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue.E-needs-testCall for participation: An issue has been fixed and does not reproduce, but no test has been added.Call for participation: An issue has been fixed and does not reproduce, but no test has been added.