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// Test that we don't duplicate storage for futures moved around in .await, and
// for futures moved into other futures.
//
// The exact sizes can change by a few bytes (we'd like to know when they do).
// What we don't want to see is the wrong multiple of 1024 (the size of BigFut)
// being reflected in the size.
//
// See issue #59123 for a full explanation.
// needs-unwind Size of Futures change on panic=abort
// run-pass
// edition:2018
use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};
const BIG_FUT_SIZE: usize = 1024;
struct BigFut(#[allow(unused_tuple_struct_fields)] [u8; BIG_FUT_SIZE]);
impl BigFut {
fn new() -> Self {
BigFut([0; BIG_FUT_SIZE])
}
}
impl Drop for BigFut {
fn drop(&mut self) {}
}
impl Future for BigFut {
type Output = ();
fn poll(self: Pin<&mut Self>, _ctx: &mut Context<'_>) -> Poll<Self::Output> {
Poll::Ready(())
}
}
#[allow(dead_code)]
struct Joiner {
a: Option<BigFut>,
b: Option<BigFut>,
c: Option<BigFut>,
}
impl Future for Joiner {
type Output = ();
fn poll(self: Pin<&mut Self>, _ctx: &mut Context<'_>) -> Poll<Self::Output> {
Poll::Ready(())
}
}
fn noop() {}
async fn single() {
let x = BigFut::new();
x.await;
}
async fn single_with_noop() {
let x = BigFut::new();
noop();
x.await;
}
async fn joined() {
let a = BigFut::new();
let b = BigFut::new();
let c = BigFut::new();
let joiner = Joiner {
a: Some(a),
b: Some(b),
c: Some(c),
};
joiner.await
}
async fn joined_with_noop() {
let a = BigFut::new();
let b = BigFut::new();
let c = BigFut::new();
let joiner = Joiner {
a: Some(a),
b: Some(b),
c: Some(c),
};
noop();
joiner.await
}
async fn mixed_sizes() {
let a = BigFut::new();
let b = BigFut::new();
let c = BigFut::new();
let d = BigFut::new();
let e = BigFut::new();
let joiner = Joiner {
a: Some(a),
b: Some(b),
c: Some(c),
};
d.await;
e.await;
joiner.await;
}
fn main() {
assert_eq!(1025, std::mem::size_of_val(&single()));
assert_eq!(1026, std::mem::size_of_val(&single_with_noop()));
assert_eq!(3076, std::mem::size_of_val(&joined()));
assert_eq!(3076, std::mem::size_of_val(&joined_with_noop()));
assert_eq!(6157, std::mem::size_of_val(&mixed_sizes()));
}
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