diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs index 85d10872b3d..9fb318e2ae7 100644 --- a/compiler/rustc_hir/src/lang_items.rs +++ b/compiler/rustc_hir/src/lang_items.rs @@ -208,6 +208,10 @@ language_item_table! { FnMut, sym::fn_mut, fn_mut_trait, Target::Trait, GenericRequirement::Exact(1); FnOnce, sym::fn_once, fn_once_trait, Target::Trait, GenericRequirement::Exact(1); + AsyncFn, sym::async_fn, async_fn_trait, Target::Trait, GenericRequirement::Exact(1); + AsyncFnMut, sym::async_fn_mut, async_fn_mut_trait, Target::Trait, GenericRequirement::Exact(1); + AsyncFnOnce, sym::async_fn_once, async_fn_once_trait, Target::Trait, GenericRequirement::Exact(1); + FnOnceOutput, sym::fn_once_output, fn_once_output, Target::AssocTy, GenericRequirement::None; Iterator, sym::iterator, iterator_trait, Target::Trait, GenericRequirement::Exact(0); diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs index d486f069989..9dc365526d4 100644 --- a/compiler/rustc_hir_typeck/src/callee.rs +++ b/compiler/rustc_hir_typeck/src/callee.rs @@ -220,6 +220,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { (self.tcx.lang_items().fn_trait(), Ident::with_dummy_span(sym::call), true), (self.tcx.lang_items().fn_mut_trait(), Ident::with_dummy_span(sym::call_mut), true), (self.tcx.lang_items().fn_once_trait(), Ident::with_dummy_span(sym::call_once), false), + (self.tcx.lang_items().async_fn_trait(), Ident::with_dummy_span(sym::async_call), true), + ( + self.tcx.lang_items().async_fn_mut_trait(), + Ident::with_dummy_span(sym::async_call_mut), + true, + ), + ( + self.tcx.lang_items().async_fn_once_trait(), + Ident::with_dummy_span(sym::async_call_once), + false, + ), ] { let Some(trait_def_id) = opt_trait_def_id else { continue }; diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index 68a83aadeba..efd5e3727b9 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -425,8 +425,14 @@ symbols! { assume, assume_init, async_await, + async_call, + async_call_mut, + async_call_once, async_closure, + async_fn, async_fn_in_trait, + async_fn_mut, + async_fn_once, async_fn_track_caller, async_for_loop, async_iterator, diff --git a/library/core/src/ops/async_function.rs b/library/core/src/ops/async_function.rs new file mode 100644 index 00000000000..965873f163e --- /dev/null +++ b/library/core/src/ops/async_function.rs @@ -0,0 +1,108 @@ +use crate::future::Future; +use crate::marker::Tuple; + +/// An async-aware version of the [`Fn`](crate::ops::Fn) trait. +/// +/// All `async fn` and functions returning futures implement this trait. +#[unstable(feature = "async_fn_traits", issue = "none")] +#[rustc_paren_sugar] +#[fundamental] +#[must_use = "async closures are lazy and do nothing unless called"] +#[cfg_attr(not(bootstrap), lang = "async_fn")] +pub trait AsyncFn: AsyncFnMut { + /// Future returned by [`AsyncFn::async_call`]. + #[unstable(feature = "async_fn_traits", issue = "none")] + type CallFuture<'a>: Future + where + Self: 'a; + + /// Call the [`AsyncFn`], returning a future which may borrow from the called closure. + #[unstable(feature = "async_fn_traits", issue = "none")] + extern "rust-call" fn async_call(&self, args: Args) -> Self::CallFuture<'_>; +} + +/// An async-aware version of the [`FnMut`](crate::ops::FnMut) trait. +/// +/// All `async fn` and functions returning futures implement this trait. +#[unstable(feature = "async_fn_traits", issue = "none")] +#[rustc_paren_sugar] +#[fundamental] +#[must_use = "async closures are lazy and do nothing unless called"] +#[cfg_attr(not(bootstrap), lang = "async_fn_mut")] +pub trait AsyncFnMut: AsyncFnOnce { + /// Future returned by [`AsyncFnMut::async_call_mut`]. + #[unstable(feature = "async_fn_traits", issue = "none")] + type CallMutFuture<'a>: Future + where + Self: 'a; + + /// Call the [`AsyncFnMut`], returning a future which may borrow from the called closure. + #[unstable(feature = "async_fn_traits", issue = "none")] + extern "rust-call" fn async_call_mut(&mut self, args: Args) -> Self::CallMutFuture<'_>; +} + +/// An async-aware version of the [`FnOnce`](crate::ops::FnOnce) trait. +/// +/// All `async fn` and functions returning futures implement this trait. +#[unstable(feature = "async_fn_traits", issue = "none")] +#[rustc_paren_sugar] +#[fundamental] +#[must_use = "async closures are lazy and do nothing unless called"] +#[cfg_attr(not(bootstrap), lang = "async_fn_once")] +pub trait AsyncFnOnce { + /// Future returned by [`AsyncFnOnce::async_call_once`]. + #[unstable(feature = "async_fn_traits", issue = "none")] + type CallOnceFuture: Future; + + /// Output type of the called closure's future. + #[unstable(feature = "async_fn_traits", issue = "none")] + type Output; + + /// Call the [`AsyncFnOnce`], returning a future which may move out of the called closure. + #[unstable(feature = "async_fn_traits", issue = "none")] + extern "rust-call" fn async_call_once(self, args: Args) -> Self::CallOnceFuture; +} + +mod impls { + use super::{AsyncFn, AsyncFnMut, AsyncFnOnce}; + use crate::future::Future; + use crate::marker::Tuple; + + #[unstable(feature = "async_fn_traits", issue = "none")] + impl, A: Tuple> AsyncFn for F + where + >::Output: Future, + { + type CallFuture<'a> = >::Output where Self: 'a; + + extern "rust-call" fn async_call(&self, args: A) -> Self::CallFuture<'_> { + self.call(args) + } + } + + #[unstable(feature = "async_fn_traits", issue = "none")] + impl, A: Tuple> AsyncFnMut for F + where + >::Output: Future, + { + type CallMutFuture<'a> = >::Output where Self: 'a; + + extern "rust-call" fn async_call_mut(&mut self, args: A) -> Self::CallMutFuture<'_> { + self.call_mut(args) + } + } + + #[unstable(feature = "async_fn_traits", issue = "none")] + impl, A: Tuple> AsyncFnOnce for F + where + >::Output: Future, + { + type CallOnceFuture = >::Output; + + type Output = <>::Output as Future>::Output; + + extern "rust-call" fn async_call_once(self, args: A) -> Self::CallOnceFuture { + self.call_once(args) + } + } +} diff --git a/library/core/src/ops/mod.rs b/library/core/src/ops/mod.rs index 35654d0b853..4289a86f89b 100644 --- a/library/core/src/ops/mod.rs +++ b/library/core/src/ops/mod.rs @@ -139,6 +139,7 @@ #![stable(feature = "rust1", since = "1.0.0")] mod arith; +mod async_function; mod bit; mod control_flow; mod coroutine; @@ -173,6 +174,9 @@ pub use self::drop::Drop; #[stable(feature = "rust1", since = "1.0.0")] pub use self::function::{Fn, FnMut, FnOnce}; +#[unstable(feature = "async_fn_traits", issue = "none")] +pub use self::async_function::{AsyncFn, AsyncFnMut, AsyncFnOnce}; + #[stable(feature = "rust1", since = "1.0.0")] pub use self::index::{Index, IndexMut}; diff --git a/tests/ui/async-await/async-fn/simple.rs b/tests/ui/async-await/async-fn/simple.rs new file mode 100644 index 00000000000..99a5d56a309 --- /dev/null +++ b/tests/ui/async-await/async-fn/simple.rs @@ -0,0 +1,16 @@ +// edition: 2021 +// check-pass + +#![feature(async_fn_traits)] + +use std::ops::AsyncFn; + +async fn foo() {} + +async fn call_asyncly(f: impl AsyncFn(i32) -> i32) -> i32 { + f(1).await +} + +fn main() { + let fut = call_asyncly(|x| async move { x + 1 }); +} diff --git a/tests/ui/did_you_mean/bad-assoc-ty.stderr b/tests/ui/did_you_mean/bad-assoc-ty.stderr index 3c474d19d1d..eed01267224 100644 --- a/tests/ui/did_you_mean/bad-assoc-ty.stderr +++ b/tests/ui/did_you_mean/bad-assoc-ty.stderr @@ -191,7 +191,14 @@ error[E0223]: ambiguous associated type --> $DIR/bad-assoc-ty.rs:33:10 | LL | type H = Fn(u8) -> (u8)::Output; - | ^^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<(dyn Fn(u8) -> u8 + 'static) as IntoFuture>::Output` + | ^^^^^^^^^^^^^^^^^^^^^^ + | +help: use fully-qualified syntax + | +LL | type H = <(dyn Fn(u8) -> u8 + 'static) as AsyncFnOnce>::Output; + | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +LL | type H = <(dyn Fn(u8) -> u8 + 'static) as IntoFuture>::Output; + | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error[E0223]: ambiguous associated type --> $DIR/bad-assoc-ty.rs:39:19