diff --git a/src/test/run-pass/async-await/async-fn-size-moved-locals.rs b/src/test/run-pass/async-await/async-fn-size-moved-locals.rs new file mode 100644 index 0000000000000..139be7fe0132b --- /dev/null +++ b/src/test/run-pass/async-await/async-fn-size-moved-locals.rs @@ -0,0 +1,98 @@ +// 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. + +// edition:2018 + +#![feature(async_await)] + +use std::future::Future; +use std::pin::Pin; +use std::task::{Context, Poll}; + +const BIG_FUT_SIZE: usize = 1024; +struct BigFut([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 { + Poll::Ready(()) + } +} + +#[allow(dead_code)] +struct Joiner { + a: Option, + b: Option, + c: Option, +} + +impl Future for Joiner { + type Output = (); + + fn poll(self: Pin<&mut Self>, _ctx: &mut Context<'_>) -> Poll { + 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 +} + +fn main() { + assert_eq!(1028, std::mem::size_of_val(&single())); + assert_eq!(1032, std::mem::size_of_val(&single_with_noop())); + assert_eq!(3084, std::mem::size_of_val(&joined())); + assert_eq!(3084, std::mem::size_of_val(&joined_with_noop())); +} diff --git a/src/test/run-pass/generator/size-moved-locals.rs b/src/test/run-pass/generator/size-moved-locals.rs new file mode 100644 index 0000000000000..9aa7ad02f3eec --- /dev/null +++ b/src/test/run-pass/generator/size-moved-locals.rs @@ -0,0 +1,48 @@ +// 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` generator 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 + +#![feature(generators, generator_trait)] + +use std::ops::Generator; + +const FOO_SIZE: usize = 1024; +struct Foo([u8; FOO_SIZE]); + +impl Drop for Foo { + fn drop(&mut self) {} +} + +fn simple() -> impl Generator { + static || { + let first = Foo([0; FOO_SIZE]); + let _second = first; + yield; + // _second dropped here + } +} + +fn noop() {} + +fn complex() -> impl Generator { + static || { + let first = Foo([0; FOO_SIZE]); + noop(); + let _second = first; + yield; + // _second dropped here + } +} + +fn main() { + assert_eq!(1028, std::mem::size_of_val(&simple())); + assert_eq!(1032, std::mem::size_of_val(&complex())); +}