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Auto merge of #115864 - compiler-errors:rpitit-sugg, r=estebank 

Suggest desugaring to return-position `impl Future` when an `async fn` in trait fails an auto trait bound

First commit allows us to store the span of the `async` keyword in HIR.

Second commit implements a suggestion to desugar an `async fn` to a return-position `impl Future` in trait to slightly improve the `Send` situation being discussed in #115822.

This suggestion is only made when `#![feature(return_type_notation)]` is not enabled -- if it is, we should instead suggest an appropriate where-clause bound.
This commit is contained in:
bors 2023-09-21 21:12:32 +00:00
parent f73d376fb6 9072415252
commit b3aa8e7168
31 changed files with 348 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
compiler/rustc_ast_lowering/src/item.rs
View File

@ -1308,7 +1308,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
fn lower_asyncness(&mut self, a: Async) -> hir::IsAsync {
match a {
Async::Yes { .. } => hir::IsAsync::Async,
Async::Yes { span, .. } => hir::IsAsync::Async(span),
Async::No => hir::IsAsync::NotAsync,
}
}

2
compiler/rustc_borrowck/src/diagnostics/region_name.rs
View File

@ -302,7 +302,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
if free_region.bound_region.is_named() {
// A named region that is actually named.
Some(RegionName { name, source: RegionNameSource::NamedFreeRegion(span) })
} else if let hir::IsAsync::Async = tcx.asyncness(self.mir_hir_id().owner) {
} else if tcx.asyncness(self.mir_hir_id().owner).is_async() {
// If we spuriously thought that the region is named, we should let the
// system generate a true name for error messages. Currently this can
// happen if we have an elided name in an async fn for example: the

18
compiler/rustc_hir/src/hir.rs
View File

@ -2853,13 +2853,13 @@ impl ImplicitSelfKind {
#[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Debug)]
#[derive(HashStable_Generic)]
pub enum IsAsync {
Async,
Async(Span),
NotAsync,
}
impl IsAsync {
pub fn is_async(self) -> bool {
self == IsAsync::Async
matches!(self, IsAsync::Async(_))
}
}
@ -3296,7 +3296,7 @@ pub struct FnHeader {
impl FnHeader {
pub fn is_async(&self) -> bool {
matches!(&self.asyncness, IsAsync::Async)
matches!(&self.asyncness, IsAsync::Async(_))
}
pub fn is_const(&self) -> bool {
@ -4091,10 +4091,10 @@ mod size_asserts {
static_assert_size!(GenericBound<'_>, 48);
static_assert_size!(Generics<'_>, 56);
static_assert_size!(Impl<'_>, 80);
static_assert_size!(ImplItem<'_>, 80);
static_assert_size!(ImplItemKind<'_>, 32);
static_assert_size!(Item<'_>, 80);
static_assert_size!(ItemKind<'_>, 48);
static_assert_size!(ImplItem<'_>, 88);
static_assert_size!(ImplItemKind<'_>, 40);
static_assert_size!(Item<'_>, 88);
static_assert_size!(ItemKind<'_>, 56);
static_assert_size!(Local<'_>, 64);
static_assert_size!(Param<'_>, 32);
static_assert_size!(Pat<'_>, 72);
@ -4105,8 +4105,8 @@ mod size_asserts {
static_assert_size!(Res, 12);
static_assert_size!(Stmt<'_>, 32);
static_assert_size!(StmtKind<'_>, 16);
static_assert_size!(TraitItem<'_>, 80);
static_assert_size!(TraitItemKind<'_>, 40);
static_assert_size!(TraitItem<'_>, 88);
static_assert_size!(TraitItemKind<'_>, 48);
static_assert_size!(Ty<'_>, 48);
static_assert_size!(TyKind<'_>, 32);
// tidy-alphabetical-end

2
compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
View File

@ -595,7 +595,7 @@ fn compare_asyncness<'tcx>(
trait_m: ty::AssocItem,
delay: bool,
) -> Result<(), ErrorGuaranteed> {
if tcx.asyncness(trait_m.def_id) == hir::IsAsync::Async {
if tcx.asyncness(trait_m.def_id).is_async() {
match tcx.fn_sig(impl_m.def_id).skip_binder().skip_binder().output().kind() {
ty::Alias(ty::Opaque, ..) => {
// allow both `async fn foo()` and `fn foo() -> impl Future`

4
compiler/rustc_hir_analysis/src/check/entry.rs
View File

@ -112,7 +112,7 @@ fn check_main_fn_ty(tcx: TyCtxt<'_>, main_def_id: DefId) {
}
let main_asyncness = tcx.asyncness(main_def_id);
if let hir::IsAsync::Async = main_asyncness {
if main_asyncness.is_async() {
let asyncness_span = main_fn_asyncness_span(tcx, main_def_id);
tcx.sess.emit_err(errors::MainFunctionAsync { span: main_span, asyncness: asyncness_span });
error = true;
@ -212,7 +212,7 @@ fn check_start_fn_ty(tcx: TyCtxt<'_>, start_def_id: DefId) {
});
error = true;
}
if let hir::IsAsync::Async = sig.header.asyncness {
if sig.header.asyncness.is_async() {
let span = tcx.def_span(it.owner_id);
tcx.sess.emit_err(errors::StartAsync { span: span });
error = true;

2
compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
View File

@ -1213,7 +1213,7 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
&& let Some(generics) = self.tcx.hir().get_generics(self.tcx.local_parent(param_id))
&& let Some(param) = generics.params.iter().find(|p| p.def_id == param_id)
&& param.is_elided_lifetime()
&& let hir::IsAsync::NotAsync = self.tcx.asyncness(lifetime_ref.hir_id.owner.def_id)
&& !self.tcx.asyncness(lifetime_ref.hir_id.owner.def_id).is_async()
&& !self.tcx.features().anonymous_lifetime_in_impl_trait
{
let mut diag = rustc_session::parse::feature_err(

2
compiler/rustc_hir_pretty/src/lib.rs
View File

@ -2304,7 +2304,7 @@ impl<'a> State<'a> {
match header.asyncness {
hir::IsAsync::NotAsync => {}
hir::IsAsync::Async => self.word_nbsp("async"),
hir::IsAsync::Async(_) => self.word_nbsp("async"),
}
self.print_unsafety(header.unsafety);

4
compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
View File

@ -987,10 +987,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let bound_vars = self.tcx.late_bound_vars(fn_id);
let ty = self.tcx.erase_late_bound_regions(Binder::bind_with_vars(ty, bound_vars));
let ty = match self.tcx.asyncness(fn_id.owner) {
hir::IsAsync::Async => self.get_impl_future_output_ty(ty).unwrap_or_else(|| {
ty::Asyncness::Yes => self.get_impl_future_output_ty(ty).unwrap_or_else(|| {
span_bug!(fn_decl.output.span(), "failed to get output type of async function")
}),
hir::IsAsync::NotAsync => ty,
ty::Asyncness::No => ty,
};
let ty = self.normalize(expr.span, ty);
if self.can_coerce(found, ty) {

3
compiler/rustc_lint/src/builtin.rs
View File

@ -41,7 +41,6 @@ use crate::{
},
EarlyContext, EarlyLintPass, LateContext, LateLintPass, Level, LintContext,
};
use hir::IsAsync;
use rustc_ast::attr;
use rustc_ast::tokenstream::{TokenStream, TokenTree};
use rustc_ast::visit::{FnCtxt, FnKind};
@ -1294,7 +1293,7 @@ impl<'tcx> LateLintPass<'tcx> for UngatedAsyncFnTrackCaller {
span: Span,
def_id: LocalDefId,
) {
if fn_kind.asyncness() == IsAsync::Async
if fn_kind.asyncness().is_async()
&& !cx.tcx.features().async_fn_track_caller
// Now, check if the function has the `#[track_caller]` attribute
&& let Some(attr) = cx.tcx.get_attr(def_id, sym::track_caller)

2
compiler/rustc_metadata/src/rmeta/mod.rs
View File

@ -439,7 +439,7 @@ define_tables! {
coerce_unsized_info: Table<DefIndex, LazyValue<ty::adjustment::CoerceUnsizedInfo>>,
mir_const_qualif: Table<DefIndex, LazyValue<mir::ConstQualifs>>,
rendered_const: Table<DefIndex, LazyValue<String>>,
asyncness: Table<DefIndex, hir::IsAsync>,
asyncness: Table<DefIndex, ty::Asyncness>,
fn_arg_names: Table<DefIndex, LazyArray<Ident>>,
generator_kind: Table<DefIndex, LazyValue<hir::GeneratorKind>>,
trait_def: Table<DefIndex, LazyValue<ty::TraitDef>>,

6
compiler/rustc_metadata/src/rmeta/table.rs
View File

@ -205,9 +205,9 @@ fixed_size_enum! {
}
fixed_size_enum! {
hir::IsAsync {
( NotAsync )
( Async )
ty::Asyncness {
( Yes )
( No )
}
}

1
compiler/rustc_middle/src/query/erase.rs
View File

@ -265,6 +265,7 @@ trivial! {
rustc_middle::ty::adjustment::CoerceUnsizedInfo,
rustc_middle::ty::AssocItem,
rustc_middle::ty::AssocItemContainer,
rustc_middle::ty::Asyncness,
rustc_middle::ty::BoundVariableKind,
rustc_middle::ty::DeducedParamAttrs,
rustc_middle::ty::Destructor,

2
compiler/rustc_middle/src/query/mod.rs
View File

@ -731,7 +731,7 @@ rustc_queries! {
separate_provide_extern
}
query asyncness(key: DefId) -> hir::IsAsync {
query asyncness(key: DefId) -> ty::Asyncness {
desc { |tcx| "checking if the function is async: `{}`", tcx.def_path_str(key) }
separate_provide_extern
}

13
compiler/rustc_middle/src/ty/mod.rs
View File

@ -280,6 +280,19 @@ impl fmt::Display for ImplPolarity {
}
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable, Debug)]
#[derive(TypeFoldable, TypeVisitable)]
pub enum Asyncness {
Yes,
No,
}
impl Asyncness {
pub fn is_async(self) -> bool {
matches!(self, Asyncness::Yes)
}
}
#[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, Encodable, Decodable, HashStable)]
pub enum Visibility<Id = LocalDefId> {
/// Visible everywhere (including in other crates).

1
compiler/rustc_middle/src/ty/parameterized.rs
View File

@ -62,6 +62,7 @@ trivially_parameterized_over_tcx! {
crate::middle::resolve_bound_vars::ObjectLifetimeDefault,
crate::mir::ConstQualifs,
ty::AssocItemContainer,
ty::Asyncness,
ty::DeducedParamAttrs,
ty::Generics,
ty::ImplPolarity,

1
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
View File

@ -987,6 +987,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
}
self.explain_hrtb_projection(&mut err, trait_predicate, obligation.param_env, &obligation.cause);
self.suggest_desugaring_async_fn_in_trait(&mut err, trait_ref);
// Return early if the trait is Debug or Display and the invocation
// originates within a standard library macro, because the output

6
compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
View File

@ -104,7 +104,9 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(sig, _, body_id), .. }) => {
self.describe_generator(*body_id).or_else(|| {
Some(match sig.header {
hir::FnHeader { asyncness: hir::IsAsync::Async, .. } => "an async function",
hir::FnHeader { asyncness: hir::IsAsync::Async(_), .. } => {
"an async function"
}
_ => "a function",
})
})
@ -118,7 +120,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
..
}) => self.describe_generator(*body_id).or_else(|| {
Some(match sig.header {
hir::FnHeader { asyncness: hir::IsAsync::Async, .. } => "an async method",
hir::FnHeader { asyncness: hir::IsAsync::Async(_), .. } => "an async method",
_ => "a method",
})
}),

136
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View File

@ -414,6 +414,12 @@ pub trait TypeErrCtxtExt<'tcx> {
param_env: ty::ParamEnv<'tcx>,
cause: &ObligationCause<'tcx>,
);
fn suggest_desugaring_async_fn_in_trait(
&self,
err: &mut Diagnostic,
trait_ref: ty::PolyTraitRef<'tcx>,
);
}
fn predicate_constraint(generics: &hir::Generics<'_>, pred: ty::Predicate<'_>) -> (Span, String) {
@ -4100,6 +4106,136 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
});
}
}
fn suggest_desugaring_async_fn_in_trait(
&self,
err: &mut Diagnostic,
trait_ref: ty::PolyTraitRef<'tcx>,
) {
// Don't suggest if RTN is active -- we should prefer a where-clause bound instead.
if self.tcx.features().return_type_notation {
return;
}
let trait_def_id = trait_ref.def_id();
// Only suggest specifying auto traits
if !self.tcx.trait_is_auto(trait_def_id) {
return;
}
// Look for an RPITIT
let ty::Alias(ty::Projection, alias_ty) = trait_ref.self_ty().skip_binder().kind() else {
return;
};
let Some(ty::ImplTraitInTraitData::Trait { fn_def_id, opaque_def_id }) =
self.tcx.opt_rpitit_info(alias_ty.def_id)
else {
return;
};
let auto_trait = self.tcx.def_path_str(trait_def_id);
// ... which is a local function
let Some(fn_def_id) = fn_def_id.as_local() else {
// If it's not local, we can at least mention that the method is async, if it is.
if self.tcx.asyncness(fn_def_id).is_async() {
err.span_note(
self.tcx.def_span(fn_def_id),
format!(
"`{}::{}` is an `async fn` in trait, which does not \
automatically imply that its future is `{auto_trait}`",
alias_ty.trait_ref(self.tcx),
self.tcx.item_name(fn_def_id)
),
);
}
return;
};
let Some(hir::Node::TraitItem(item)) = self.tcx.hir().find_by_def_id(fn_def_id) else {
return;
};
// ... whose signature is `async` (i.e. this is an AFIT)
let (sig, body) = item.expect_fn();
let hir::IsAsync::Async(async_span) = sig.header.asyncness else {
return;
};
let Ok(async_span) =
self.tcx.sess.source_map().span_extend_while(async_span, |c| c.is_whitespace())
else {
return;
};
let hir::FnRetTy::Return(hir::Ty { kind: hir::TyKind::OpaqueDef(def, ..), .. }) =
sig.decl.output
else {
// This should never happen, but let's not ICE.
return;
};
// Check that this is *not* a nested `impl Future` RPIT in an async fn
// (i.e. `async fn foo() -> impl Future`)
if def.owner_id.to_def_id() != opaque_def_id {
return;
}
let future = self.tcx.hir().item(*def).expect_opaque_ty();
let Some(hir::GenericBound::LangItemTrait(_, _, _, generics)) = future.bounds.get(0) else {
// `async fn` should always lower to a lang item bound... but don't ICE.
return;
};
let Some(hir::TypeBindingKind::Equality { term: hir::Term::Ty(future_output_ty) }) =
generics.bindings.get(0).map(|binding| binding.kind)
else {
// Also should never happen.
return;
};
let function_name = self.tcx.def_path_str(fn_def_id);
let mut sugg = if future_output_ty.span.is_empty() {
vec![
(async_span, String::new()),
(
future_output_ty.span,
format!(" -> impl std::future::Future<Output = ()> + {auto_trait}"),
),
]
} else {
vec![
(
future_output_ty.span.shrink_to_lo(),
"impl std::future::Future<Output = ".to_owned(),
),
(future_output_ty.span.shrink_to_hi(), format!("> + {auto_trait}")),
(async_span, String::new()),
]
};
// If there's a body, we also need to wrap it in `async {}`
if let hir::TraitFn::Provided(body) = body {
let body = self.tcx.hir().body(*body);
let body_span = body.value.span;
let body_span_without_braces =
body_span.with_lo(body_span.lo() + BytePos(1)).with_hi(body_span.hi() - BytePos(1));
if body_span_without_braces.is_empty() {
sugg.push((body_span_without_braces, " async {} ".to_owned()));
} else {
sugg.extend([
(body_span_without_braces.shrink_to_lo(), "async {".to_owned()),
(body_span_without_braces.shrink_to_hi(), "} ".to_owned()),
]);
}
}
err.multipart_suggestion(
format!(
"`{auto_trait}` can be made part of the associated future's \
guarantees for all implementations of `{function_name}`"
),
sugg,
Applicability::MachineApplicable,
);
}
}
/// Add a hint to add a missing borrow or remove an unnecessary one.

7
compiler/rustc_ty_utils/src/ty.rs
View File

@ -296,9 +296,12 @@ fn issue33140_self_ty(tcx: TyCtxt<'_>, def_id: DefId) -> Option<EarlyBinder<Ty<'
}
/// Check if a function is async.
fn asyncness(tcx: TyCtxt<'_>, def_id: LocalDefId) -> hir::IsAsync {
fn asyncness(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Asyncness {
let node = tcx.hir().get_by_def_id(def_id);
node.fn_sig().map_or(hir::IsAsync::NotAsync, |sig| sig.header.asyncness)
node.fn_sig().map_or(ty::Asyncness::No, |sig| match sig.header.asyncness {
hir::IsAsync::Async(_) => ty::Asyncness::Yes,
hir::IsAsync::NotAsync => ty::Asyncness::No,
})
}
fn unsizing_params_for_adt<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> BitSet<u32> {

8
src/librustdoc/clean/types.rs
View File

@ -31,7 +31,7 @@ use rustc_resolve::rustdoc::{
use rustc_session::Session;
use rustc_span::hygiene::MacroKind;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{self, FileName, Loc};
use rustc_span::{self, FileName, Loc, DUMMY_SP};
use rustc_target::abi::VariantIdx;
use rustc_target::spec::abi::Abi;
@ -622,7 +622,7 @@ impl Item {
fn build_fn_header(
def_id: DefId,
tcx: TyCtxt<'_>,
asyncness: hir::IsAsync,
asyncness: ty::Asyncness,
) -> hir::FnHeader {
let sig = tcx.fn_sig(def_id).skip_binder();
let constness =
@ -631,6 +631,10 @@ impl Item {
} else {
hir::Constness::NotConst
};
let asyncness = match asyncness {
ty::Asyncness::Yes => hir::IsAsync::Async(DUMMY_SP),
ty::Asyncness::No => hir::IsAsync::NotAsync,
};
hir::FnHeader { unsafety: sig.unsafety(), abi: sig.abi(), constness, asyncness }
}
let header = match *self.kind {

2
src/librustdoc/html/format.rs
View File

@ -1599,7 +1599,7 @@ impl PrintWithSpace for hir::Unsafety {
impl PrintWithSpace for hir::IsAsync {
fn print_with_space(&self) -> &str {
match self {
hir::IsAsync::Async => "async ",
hir::IsAsync::Async(_) => "async ",
hir::IsAsync::NotAsync => "",
}
}

7
src/tools/clippy/clippy_lints/src/redundant_closure_call.rs
View File

@ -10,6 +10,7 @@ use rustc_hir::intravisit::{Visitor as HirVisitor, Visitor};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::nested_filter;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
@ -84,7 +85,7 @@ fn find_innermost_closure<'tcx>(
cx: &LateContext<'tcx>,
mut expr: &'tcx hir::Expr<'tcx>,
mut steps: usize,
) -> Option<(&'tcx hir::Expr<'tcx>, &'tcx hir::FnDecl<'tcx>, hir::IsAsync)> {
) -> Option<(&'tcx hir::Expr<'tcx>, &'tcx hir::FnDecl<'tcx>, ty::Asyncness)> {
let mut data = None;
while let hir::ExprKind::Closure(closure) = expr.kind
@ -98,9 +99,9 @@ fn find_innermost_closure<'tcx>(
{
expr = body.value;
data = Some((body.value, closure.fn_decl, if is_async_closure(body) {
hir::IsAsync::Async
ty::Asyncness::Yes
} else {
hir::IsAsync::NotAsync
ty::Asyncness::No
}));
steps -= 1;
}

6
src/tools/clippy/clippy_utils/src/lib.rs
View File

@ -90,7 +90,7 @@ use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
use rustc_hir::LangItem::{OptionNone, OptionSome, ResultErr, ResultOk};
use rustc_hir::{
self as hir, def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Closure, Destination, Expr,
ExprField, ExprKind, FnDecl, FnRetTy, GenericArgs, HirId, Impl, ImplItem, ImplItemKind, ImplItemRef, IsAsync, Item,
ExprField, ExprKind, FnDecl, FnRetTy, GenericArgs, HirId, Impl, ImplItem, ImplItemKind, ImplItemRef, Item,
ItemKind, LangItem, Local, MatchSource, Mutability, Node, OwnerId, Param, Pat, PatKind, Path, PathSegment, PrimTy,
QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitItemRef, TraitRef, TyKind, UnOp,
};
@ -1958,8 +1958,8 @@ pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>,
/// Checks if the given function kind is an async function.
pub fn is_async_fn(kind: FnKind<'_>) -> bool {
match kind {
FnKind::ItemFn(_, _, header) => header.asyncness == IsAsync::Async,
FnKind::Method(_, sig) => sig.header.asyncness == IsAsync::Async,
FnKind::ItemFn(_, _, header) => header.asyncness .is_async(),
FnKind::Method(_, sig) => sig.header.asyncness.is_async(),
FnKind::Closure => false,
}
}

7
tests/ui/async-await/in-trait/auxiliary/foreign-async-fn.rs Normal file
View File

@ -0,0 +1,7 @@
// edition:2021
#![feature(async_fn_in_trait)]
pub trait Foo {
async fn test();
}

5
tests/ui/async-await/in-trait/missing-send-bound.stderr
View File

@ -15,6 +15,11 @@ note: required by a bound in `assert_is_send`
|
LL | fn assert_is_send(_: impl Send) {}
| ^^^^ required by this bound in `assert_is_send`
help: `Send` can be made part of the associated future's guarantees for all implementations of `Foo::bar`
|
LL - async fn bar();
LL + fn bar() -> impl std::future::Future<Output = ()> + Send;
|
error: aborting due to previous error

20
tests/ui/async-await/in-trait/send-on-async-fn-in-trait.fixed Normal file
View File

@ -0,0 +1,20 @@
// run-rustfix
// edition: 2021
#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
#![allow(unused)]
trait Foo {
fn test() -> impl std::future::Future<Output = ()> + Send { async {} }
fn test2() -> impl std::future::Future<Output = i32> + Send {async { 1 + 2 } }
}
fn bar<T: Foo>() {
fn needs_send(_: impl Send) {}
needs_send(T::test());
//~^ ERROR `impl Future<Output = ()>` cannot be sent between threads safely
needs_send(T::test2());
//~^ ERROR `impl Future<Output = i32>` cannot be sent between threads safely
}
fn main() {}

20
tests/ui/async-await/in-trait/send-on-async-fn-in-trait.rs Normal file
View File

@ -0,0 +1,20 @@
// run-rustfix
// edition: 2021
#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
#![allow(unused)]
trait Foo {
async fn test() -> () {}
async fn test2() -> i32 { 1 + 2 }
}
fn bar<T: Foo>() {
fn needs_send(_: impl Send) {}
needs_send(T::test());
//~^ ERROR `impl Future<Output = ()>` cannot be sent between threads safely
needs_send(T::test2());
//~^ ERROR `impl Future<Output = i32>` cannot be sent between threads safely
}
fn main() {}

43
tests/ui/async-await/in-trait/send-on-async-fn-in-trait.stderr Normal file
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@ -0,0 +1,43 @@
error[E0277]: `impl Future<Output = ()>` cannot be sent between threads safely
--> $DIR/send-on-async-fn-in-trait.rs:14:16
|
LL | needs_send(T::test());
| ---------- ^^^^^^^^^ `impl Future<Output = ()>` cannot be sent between threads safely
| |
| required by a bound introduced by this call
|
= help: the trait `Send` is not implemented for `impl Future<Output = ()>`
note: required by a bound in `needs_send`
--> $DIR/send-on-async-fn-in-trait.rs:13:27
|
LL | fn needs_send(_: impl Send) {}
| ^^^^ required by this bound in `needs_send`
help: `Send` can be made part of the associated future's guarantees for all implementations of `Foo::test`
|
LL - async fn test() -> () {}
LL + fn test() -> impl std::future::Future<Output = ()> + Send { async {} }
|
error[E0277]: `impl Future<Output = i32>` cannot be sent between threads safely
--> $DIR/send-on-async-fn-in-trait.rs:16:16
|
LL | needs_send(T::test2());
| ---------- ^^^^^^^^^^ `impl Future<Output = i32>` cannot be sent between threads safely
| |
| required by a bound introduced by this call
|
= help: the trait `Send` is not implemented for `impl Future<Output = i32>`
note: required by a bound in `needs_send`
--> $DIR/send-on-async-fn-in-trait.rs:13:27
|
LL | fn needs_send(_: impl Send) {}
| ^^^^ required by this bound in `needs_send`
help: `Send` can be made part of the associated future's guarantees for all implementations of `Foo::test2`
|
LL - async fn test2() -> i32 { 1 + 2 }
LL + fn test2() -> impl std::future::Future<Output = i32> + Send {async { 1 + 2 } }
|
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0277`.

15
tests/ui/async-await/in-trait/send-on-foreign-async-fn-in-trait.rs Normal file
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@ -0,0 +1,15 @@
// aux-build:foreign-async-fn.rs
// edition:2021
#![feature(async_fn_in_trait)]
extern crate foreign_async_fn;
use foreign_async_fn::Foo;
fn bar<T: Foo>() {
fn needs_send(_: impl Send) {}
needs_send(T::test());
//~^ ERROR `impl Future<Output = ()>` cannot be sent between threads safely
}
fn main() {}

23
tests/ui/async-await/in-trait/send-on-foreign-async-fn-in-trait.stderr Normal file
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@ -0,0 +1,23 @@
error[E0277]: `impl Future<Output = ()>` cannot be sent between threads safely
--> $DIR/send-on-foreign-async-fn-in-trait.rs:11:16
|
LL | needs_send(T::test());
| ---------- ^^^^^^^^^ `impl Future<Output = ()>` cannot be sent between threads safely
| |
| required by a bound introduced by this call
|
= help: the trait `Send` is not implemented for `impl Future<Output = ()>`
note: `<T as Foo>::test` is an `async fn` in trait, which does not automatically imply that its future is `Send`
--> $DIR/auxiliary/foreign-async-fn.rs:6:5
|
LL | async fn test();
| ^^^^^^^^^^^^^^^^
note: required by a bound in `needs_send`
--> $DIR/send-on-foreign-async-fn-in-trait.rs:10:27
|
LL | fn needs_send(_: impl Send) {}
| ^^^^ required by this bound in `needs_send`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0277`.

32
tests/ui/stats/hir-stats.stderr
View File

@ -146,33 +146,33 @@ hir-stats - Trait 192 ( 2.1%) 4
hir-stats WherePredicate 192 ( 2.1%) 3 64
hir-stats - BoundPredicate 192 ( 2.1%) 3
hir-stats Block 288 ( 3.2%) 6 48
hir-stats Pat 360 ( 4.0%) 5 72
hir-stats Pat 360 ( 3.9%) 5 72
hir-stats - Wild 72 ( 0.8%) 1
hir-stats - Struct 72 ( 0.8%) 1
hir-stats - Binding 216 ( 2.4%) 3
hir-stats GenericParam 400 ( 4.4%) 5 80
hir-stats Generics 560 ( 6.2%) 10 56
hir-stats Ty 720 ( 8.0%) 15 48
hir-stats Generics 560 ( 6.1%) 10 56
hir-stats Ty 720 ( 7.9%) 15 48
hir-stats - Ptr 48 ( 0.5%) 1
hir-stats - Ref 48 ( 0.5%) 1
hir-stats - Path 624 ( 6.9%) 13
hir-stats Expr 768 ( 8.5%) 12 64
hir-stats - Path 624 ( 6.8%) 13
hir-stats Expr 768 ( 8.4%) 12 64
hir-stats - Path 64 ( 0.7%) 1
hir-stats - Struct 64 ( 0.7%) 1
hir-stats - Match 64 ( 0.7%) 1
hir-stats - InlineAsm 64 ( 0.7%) 1
hir-stats - Lit 128 ( 1.4%) 2
hir-stats - Block 384 ( 4.2%) 6
hir-stats Item 880 ( 9.7%) 11 80
hir-stats - Trait 80 ( 0.9%) 1
hir-stats - Enum 80 ( 0.9%) 1
hir-stats - ExternCrate 80 ( 0.9%) 1
hir-stats - ForeignMod 80 ( 0.9%) 1
hir-stats - Impl 80 ( 0.9%) 1
hir-stats - Fn 160 ( 1.8%) 2
hir-stats - Use 320 ( 3.5%) 4
hir-stats Path 1_240 (13.7%) 31 40
hir-stats PathSegment 1_920 (21.2%) 40 48
hir-stats Item 968 (10.6%) 11 88
hir-stats - Trait 88 ( 1.0%) 1
hir-stats - Enum 88 ( 1.0%) 1
hir-stats - ExternCrate 88 ( 1.0%) 1
hir-stats - ForeignMod 88 ( 1.0%) 1
hir-stats - Impl 88 ( 1.0%) 1
hir-stats - Fn 176 ( 1.9%) 2
hir-stats - Use 352 ( 3.9%) 4
hir-stats Path 1_240 (13.6%) 31 40
hir-stats PathSegment 1_920 (21.0%) 40 48
hir-stats ----------------------------------------------------------------
hir-stats Total 9_048
hir-stats Total 9_136
hir-stats