rust/tests/ui/rfcs/rfc-2632-const-trait-impl/effects/helloworld.rs

//@ check-pass

// gate-test-effects
// ^ effects doesn't have a gate so we will trick tidy into thinking this is a gate test

#![feature(const_trait_impl, effects, core_intrinsics, const_eval_select)]

// ensure we are passing in the correct host effect in always const contexts.

pub const fn hmm<T>() -> usize {
    // FIXME(const_trait_impl): maybe we should have a way to refer to the (hidden) effect param
    fn one() -> usize { 1 }
    const fn zero() -> usize { 0 }
    unsafe {
        std::intrinsics::const_eval_select((), zero, one)
    }
}

const _: () = {
    let x = hmm::<()>();
    assert!(0 == x);
};

pub const fn uwu(x: [u8; hmm::<()>()]) {
    let [] = x;
}

fn main() {}