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Split out async_fn_in_trait into a separate feature

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PR #101224 added support for async fn in trait desuraging behind the
return_position_impl_trait_in_trait feature.

Split this out so that it's behind its own feature gate, since async fn
in trait doesn't need to follow the same stabilization schedule.
This commit is contained in:
Dan Johnson 2022-08-18 16:27:16 -07:00
parent 9062b780b3
commit d0a07495be
13 changed files with 133 additions and 19 deletions
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23
compiler/rustc_ast_lowering/src/lib.rs
View file

@ -332,6 +332,15 @@ impl FnDeclKind {
_ => false,
}
}
fn async_fn_allowed(&self, tcx: TyCtxt<'_>) -> bool {
match self {
FnDeclKind::Fn | FnDeclKind::Inherent => true,
FnDeclKind::Impl if tcx.features().async_fn_in_trait => true,
FnDeclKind::Trait if tcx.features().async_fn_in_trait => true,
_ => false,
}
}
}
#[derive(Copy, Clone)]
@ -1692,14 +1701,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}));
let output = if let Some((ret_id, span)) = make_ret_async {
if !kind.impl_trait_allowed(self.tcx) {
if !kind.async_fn_allowed(self.tcx) {
match kind {
FnDeclKind::Trait | FnDeclKind::Impl => {
self.tcx
.sess
.create_feature_err(
TraitFnAsync { fn_span, span },
sym::return_position_impl_trait_in_trait,
sym::async_fn_in_trait,
)
.emit();
}
@ -1917,9 +1926,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
let future_bound = this.lower_async_fn_output_type_to_future_bound(
output,
span,
ImplTraitContext::ReturnPositionOpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
in_trait,
if in_trait && !this.tcx.features().return_position_impl_trait_in_trait {
ImplTraitContext::Disallowed(ImplTraitPosition::TraitReturn)
} else {
ImplTraitContext::ReturnPositionOpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
in_trait,
}
},
);

2
compiler/rustc_feature/src/active.rs
View file

@ -312,6 +312,8 @@ declare_features! (
(active, associated_type_defaults, "1.2.0", Some(29661), None),
/// Allows `async || body` closures.
(active, async_closure, "1.37.0", Some(62290), None),
/// Alows async functions to be declared, implemented, and used in traits.
(incomplete, async_fn_in_trait, "CURRENT_RUSTC_VERSION", Some(91611), None),
/// Allows `extern "C-unwind" fn` to enable unwinding across ABI boundaries.
(active, c_unwind, "1.52.0", Some(74990), None),
/// Allows using C-variadics.

1
compiler/rustc_span/src/symbol.rs
View file

@ -396,6 +396,7 @@ symbols! {
assume_init,
async_await,
async_closure,
async_fn_in_trait,
atomic,
atomic_mod,
atomics,

6
src/test/ui/async-await/async-trait-fn.stderr
View file

@ -9,7 +9,7 @@ LL | async fn foo() {}
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/async-trait-fn.rs:5:5
@ -22,7 +22,7 @@ LL | async fn bar(&self) {}
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/async-trait-fn.rs:7:5
@ -35,7 +35,7 @@ LL | async fn baz() {
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0308]: mismatched types
--> $DIR/async-trait-fn.rs:3:20

2
src/test/ui/async-await/edition-deny-async-fns-2015.stderr
View file

@ -90,7 +90,7 @@ LL | async fn foo() {}
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0308]: mismatched types
--> $DIR/edition-deny-async-fns-2015.rs:18:20

25
src/test/ui/async-await/feature-gate-async_fn_in_trait.rs Normal file
View file

@ -0,0 +1,25 @@
// edition:2021
// RPITIT is not enough to allow use of async functions
#![allow(incomplete_features)]
#![feature(return_position_impl_trait_in_trait)]
trait T {
async fn foo(); //~ ERROR functions in traits cannot be declared `async`
}
// Both return_position_impl_trait_in_trait and async_fn_in_trait are required for this (see also
// feature-gate-return_position_impl_trait_in_trait.rs)
trait T2 {
async fn foo() -> impl Sized; //~ ERROR functions in traits cannot be declared `async`
}
trait T3 {
fn foo() -> impl std::future::Future<Output = ()>;
}
impl T3 for () {
async fn foo() {} //~ ERROR functions in traits cannot be declared `async`
}
fn main() {}

42
src/test/ui/async-await/feature-gate-async_fn_in_trait.stderr Normal file
View file

@ -0,0 +1,42 @@
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/feature-gate-async_fn_in_trait.rs:8:5
|
LL | async fn foo();
| -----^^^^^^^^^^
| |
| `async` because of this
|
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/feature-gate-async_fn_in_trait.rs:14:5
|
LL | async fn foo() -> impl Sized;
| -----^^^^^^^^^^^^^^^^^^^^^^^^
| |
| `async` because of this
|
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/feature-gate-async_fn_in_trait.rs:22:5
|
LL | async fn foo() {}
| -----^^^^^^^^^
| |
| `async` because of this
|
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0706`.

2
src/test/ui/async-await/issues/issue-95307.stderr
View file

@ -9,7 +9,7 @@ LL | async fn new() -> [u8; _];
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/issue-95307.rs:7:28

13
src/test/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.rs
View file

@ -1,5 +1,18 @@
// edition:2021
// async_fn_in_trait is not enough to allow use of RPITIT
#![allow(incomplete_features)]
#![feature(async_fn_in_trait)]
trait Foo {
fn bar() -> impl Sized; //~ ERROR `impl Trait` only allowed in function and inherent method return types, not in trait method return
fn baz() -> Box<impl std::fmt::Display>; //~ ERROR `impl Trait` only allowed in function and inherent method return types, not in trait method return
}
// Both return_position_impl_trait_in_trait and async_fn_in_trait are required for this (see also
// feature-gate-async_fn_in_trait.rs)
trait AsyncFoo {
async fn bar() -> impl Sized; //~ ERROR `impl Trait` only allowed in function and inherent method return types, not in trait method return
}
fn main() {}

22
src/test/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.stderr
View file

@ -1,5 +1,5 @@
error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
--> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:2:17
--> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:8:17
|
LL | fn bar() -> impl Sized;
| ^^^^^^^^^^
@ -7,6 +7,24 @@ LL | fn bar() -> impl Sized;
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
error: aborting due to previous error
error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
--> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:9:21
|
LL | fn baz() -> Box<impl std::fmt::Display>;
| ^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
--> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:15:23
|
LL | async fn bar() -> impl Sized;
| ^^^^^^^^^^
|
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0562`.

8
src/test/ui/parser/fn-header-semantic-fail.stderr
View file

@ -147,7 +147,7 @@ LL | async fn ft1();
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/fn-header-semantic-fail.rs:21:9
@ -160,7 +160,7 @@ LL | const async unsafe extern "C" fn ft5();
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/fn-header-semantic-fail.rs:29:9
@ -173,7 +173,7 @@ LL | async fn ft1() {}
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/fn-header-semantic-fail.rs:33:9
@ -186,7 +186,7 @@ LL | const async unsafe extern "C" fn ft5() {}
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0391]: cycle detected when computing type of `main::ff5::{opaque#0}`
--> $DIR/fn-header-semantic-fail.rs:12:44

4
src/test/ui/resolve/issue-70736-async-fn-no-body-def-collector.stderr
View file

@ -33,7 +33,7 @@ LL | async fn associated();
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
--> $DIR/issue-70736-async-fn-no-body-def-collector.rs:15:5
@ -46,7 +46,7 @@ LL | async fn associated();
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error: aborting due to 5 previous errors

2
src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr
View file

@ -51,7 +51,7 @@ LL | trait C{async fn new(val: T) {}
= note: `async` trait functions are not currently supported
= note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
warning: changes to closure capture in Rust 2021 will affect drop order
--> $DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs:6:57