conditional-drop.rs

//@ run-pass

//@ revisions: default nomiropt
//@[nomiropt]compile-flags: -Z mir-opt-level=0

#![feature(coroutines, coroutine_trait, stmt_expr_attributes)]

use std::ops::Coroutine;
use std::pin::Pin;
use std::sync::atomic::{AtomicUsize, Ordering};

static A: AtomicUsize = AtomicUsize::new(0);

struct B;

impl Drop for B {
    fn drop(&mut self) {
        A.fetch_add(1, Ordering::SeqCst);
    }
}


fn test() -> bool { true }
fn test2() -> bool { false }

fn main() {
    t1();
    t2();
}

fn t1() {
    let mut a = #[coroutine] || {
        let b = B;
        if test() {
            drop(b);
        }
        yield;
    };

    let n = A.load(Ordering::SeqCst);
    Pin::new(&mut a).resume(());
    assert_eq!(A.load(Ordering::SeqCst), n + 1);
    Pin::new(&mut a).resume(());
    assert_eq!(A.load(Ordering::SeqCst), n + 1);
}

fn t2() {
    let mut a = #[coroutine] || {
        let b = B;
        if test2() {
            drop(b);
        }
        yield;
    };

    let n = A.load(Ordering::SeqCst);
    Pin::new(&mut a).resume(());
    assert_eq!(A.load(Ordering::SeqCst), n);
    Pin::new(&mut a).resume(());
    assert_eq!(A.load(Ordering::SeqCst), n + 1);
}