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// Test that we don't store uninitialized locals in futures from `async fn`.
//
// 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 `Big`)
// being reflected in the size.
// ignore-emscripten (sizes don't match)
// run-pass
// edition:2018
#![allow(unused_variables, unused_assignments)]
use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};
const BIG_FUT_SIZE: usize = 1024;
struct Big(#[allow(unused_tuple_struct_fields)] [u8; BIG_FUT_SIZE]);
impl Big {
fn new() -> Self {
Big([0; BIG_FUT_SIZE])
}
}
impl Drop for Big {
fn drop(&mut self) {}
}
#[allow(dead_code)]
struct Joiner {
a: Option<Big>,
b: Option<Big>,
c: Option<Big>,
}
impl Future for Joiner {
type Output = ();
fn poll(self: Pin<&mut Self>, _ctx: &mut Context<'_>) -> Poll<Self::Output> {
Poll::Ready(())
}
}
fn noop() {}
async fn fut() {}
async fn single() {
let x;
fut().await;
x = Big::new();
}
async fn single_with_noop() {
let x;
fut().await;
noop();
x = Big::new();
noop();
}
async fn joined() {
let joiner;
let a = Big::new();
let b = Big::new();
let c = Big::new();
fut().await;
noop();
joiner = Joiner { a: Some(a), b: Some(b), c: Some(c) };
noop();
}
async fn joined_with_noop() {
let joiner;
let a = Big::new();
let b = Big::new();
let c = Big::new();
fut().await;
noop();
joiner = Joiner { a: Some(a), b: Some(b), c: Some(c) };
noop();
}
async fn join_retval() -> Joiner {
let a = Big::new();
let b = Big::new();
let c = Big::new();
fut().await;
noop();
Joiner { a: Some(a), b: Some(b), c: Some(c) }
}
fn main() {
assert_eq!(2, std::mem::size_of_val(&single()));
assert_eq!(3, std::mem::size_of_val(&single_with_noop()));
assert_eq!(3078, std::mem::size_of_val(&joined()));
assert_eq!(3078, std::mem::size_of_val(&joined_with_noop()));
assert_eq!(3074, std::mem::size_of_val(&join_retval()));
}
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