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//@ edition:2018
// Test that we get the expected borrow check errors when an async
// function (which takes multiple lifetimes) only returns data from
// one of them.
async fn multiple_named_lifetimes<'a, 'b>(a: &'a u8, _: &'b u8) -> &'a u8 {
a
}
// Both are borrowed whilst the future is live.
async fn future_live() {
let mut a = 22;
let mut b = 44;
let future = multiple_named_lifetimes(&a, &b);
a += 1; //~ ERROR cannot assign
b += 1; //~ ERROR cannot assign
let p = future.await;
drop(p);
}
// Just the return value is live after future is awaited.
async fn just_return_live() {
let mut a = 22;
let mut b = 44;
let future = multiple_named_lifetimes(&a, &b);
let p = future.await;
a += 1; //~ ERROR cannot assign
b += 1;
drop(p);
}
// Once `p` is dead, both `a` and `b` are unborrowed.
async fn after_both_dead() {
let mut a = 22;
let mut b = 44;
let future = multiple_named_lifetimes(&a, &b);
let p = future.await;
drop(p);
a += 1;
b += 1;
}
fn main() { }
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