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Rollup merge of #52995 - cramertj:smaller-await, r=withoutboats

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Remove unnecessary local in await! generator

This makes `async { await!(future::ready(())) }` 4 bytes instead of 16. [Playground example](http://play.rust-lang.org/?gist=54c075599b9ff390fe505c75d6b98feb&version=nightly&mode=debug&edition=2018)
This commit is contained in:
kennytm 2018-08-04 14:35:53 +08:00 • committed by GitHub
commit 59bfa8a884
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2 changed files with 11 additions and 8 deletions
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4
src/libstd/future.rs
View file

@ -108,9 +108,9 @@ where
#[unstable(feature = "gen_future", issue = "50547")]
/// Polls a future in the current thread-local task context.
pub fn poll_in_task_cx<F>(f: &mut PinMut<F>) -> Poll<F::Output>
pub fn poll_in_task_cx<F>(f: PinMut<F>) -> Poll<F::Output>
where
F: Future
{
get_task_cx(|cx| f.reborrow().poll(cx))
get_task_cx(|cx| f.poll(cx))
}

15
src/libstd/macros.rs
View file

@ -227,14 +227,17 @@ macro_rules! eprintln {
macro_rules! await {
($e:expr) => { {
let mut pinned = $e;
let mut pinned = unsafe { $crate::mem::PinMut::new_unchecked(&mut pinned) };
loop {
match $crate::future::poll_in_task_cx(&mut pinned) {
// FIXME(cramertj) prior to stabilizing await, we have to ensure that this
// can't be used to create a generator on stable via `|| await!()`.
$crate::task::Poll::Pending => yield,
$crate::task::Poll::Ready(x) => break x,
if let $crate::task::Poll::Ready(x) =
$crate::future::poll_in_task_cx(unsafe {
$crate::mem::PinMut::new_unchecked(&mut pinned)
})
{
break x;
}
// FIXME(cramertj) prior to stabilizing await, we have to ensure that this
// can't be used to create a generator on stable via `|| await!()`.
yield
}
} }
}