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//@ run-pass
// Test that we don't duplicate storage for a variable that is moved to another
// binding. This used to happen in the presence of unwind and drop edges (see
// `complex` below.)
//
// The exact sizes here can change (we'd like to know when they do). What we
// don't want to see is the `complex` coroutine size being upwards of 2048 bytes
// (which would indicate it is reserving space for two copies of Foo.)
//
// See issue #59123 for a full explanation.
//@ edition:2018
//@ needs-unwind Size of Closures change on panic=abort
#![feature(coroutines, coroutine_trait)]
use std::ops::Coroutine;
const FOO_SIZE: usize = 1024;
struct Foo(#[allow(dead_code)] [u8; FOO_SIZE]);
impl Drop for Foo {
fn drop(&mut self) {}
}
fn move_before_yield() -> impl Coroutine<Yield = (), Return = ()> {
static || {
let first = Foo([0; FOO_SIZE]);
let _second = first;
yield;
// _second dropped here
}
}
fn noop() {}
fn move_before_yield_with_noop() -> impl Coroutine<Yield = (), Return = ()> {
static || {
let first = Foo([0; FOO_SIZE]);
noop();
let _second = first;
yield;
// _second dropped here
}
}
// Today we don't have NRVO (we allocate space for both `first` and `second`,)
// but we can overlap `first` with `_third`.
fn overlap_move_points() -> impl Coroutine<Yield = (), Return = ()> {
static || {
let first = Foo([0; FOO_SIZE]);
yield;
let second = first;
yield;
let _third = second;
yield;
}
}
fn overlap_x_and_y() -> impl Coroutine<Yield = (), Return = ()> {
static || {
let x = Foo([0; FOO_SIZE]);
yield;
drop(x);
let y = Foo([0; FOO_SIZE]);
yield;
drop(y);
}
}
fn main() {
assert_eq!(1025, std::mem::size_of_val(&move_before_yield()));
assert_eq!(1026, std::mem::size_of_val(&move_before_yield_with_noop()));
assert_eq!(2051, std::mem::size_of_val(&overlap_move_points()));
assert_eq!(1026, std::mem::size_of_val(&overlap_x_and_y()));
}
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