Make async/await lowering use resume arguments
This commit is contained in:
Jonas Schievink
parent
18adc45a26
commit
dfcfa170f5
5 changed files with 86 additions and 23 deletions
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@ -10,6 +10,7 @@ use rustc_hir as hir;
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use rustc_hir::def::Res;
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use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned};
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use rustc_span::symbol::{sym, Symbol};
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use rustc_span::DUMMY_SP;
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impl<'hir> LoweringContext<'_, 'hir> {
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fn lower_exprs(&mut self, exprs: &[AstP<Expr>]) -> &'hir [hir::Expr<'hir>] {
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@ -483,14 +484,44 @@ impl<'hir> LoweringContext<'_, 'hir> {
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Some(ty) => FnRetTy::Ty(ty),
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None => FnRetTy::Default(span),
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};
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let ast_decl = FnDecl { inputs: vec![], output };
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let task_context_id = self.resolver.next_node_id();
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let task_context_hid = self.lower_node_id(task_context_id);
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let ast_decl = FnDecl {
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inputs: vec![Param {
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attrs: AttrVec::new(),
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ty: AstP(Ty {
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id: self.resolver.next_node_id(),
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kind: TyKind::Infer,
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span: DUMMY_SP,
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}),
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pat: AstP(Pat {
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id: task_context_id,
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kind: PatKind::Ident(
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BindingMode::ByValue(Mutability::Mut),
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Ident::with_dummy_span(sym::_task_context),
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None,
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),
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span: DUMMY_SP,
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}),
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id: self.resolver.next_node_id(),
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span: DUMMY_SP,
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is_placeholder: false,
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}],
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output,
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};
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let decl = self.lower_fn_decl(&ast_decl, None, /* impl trait allowed */ false, None);
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let body_id = self.lower_fn_body(&ast_decl, |this| {
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this.generator_kind = Some(hir::GeneratorKind::Async(async_gen_kind));
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body(this)
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let old_ctx = this.task_context;
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this.task_context = Some(task_context_hid);
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let res = body(this);
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this.task_context = old_ctx;
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res
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});
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// `static || -> <ret_ty> { body }`:
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// `static |task_context| -> <ret_ty> { body }`:
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let generator_kind = hir::ExprKind::Closure(
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capture_clause,
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decl,
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@ -523,9 +554,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
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/// ```rust
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/// match <expr> {
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/// mut pinned => loop {
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/// match ::std::future::poll_with_tls_context(unsafe {
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/// <::std::pin::Pin>::new_unchecked(&mut pinned)
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/// }) {
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/// match unsafe { ::std::future::poll_with_context(
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/// <::std::pin::Pin>::new_unchecked(&mut pinned),
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/// task_context,
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/// ) } {
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/// ::std::task::Poll::Ready(result) => break result,
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/// ::std::task::Poll::Pending => {}
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/// }
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@ -561,12 +593,23 @@ impl<'hir> LoweringContext<'_, 'hir> {
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let (pinned_pat, pinned_pat_hid) =
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self.pat_ident_binding_mode(span, pinned_ident, hir::BindingAnnotation::Mutable);
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// ::std::future::poll_with_tls_context(unsafe {
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// ::std::pin::Pin::new_unchecked(&mut pinned)
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// })`
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let task_context_ident = Ident::with_dummy_span(sym::_task_context);
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// unsafe {
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// ::std::future::poll_with_context(
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// ::std::pin::Pin::new_unchecked(&mut pinned),
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// task_context,
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// )
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// }
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let poll_expr = {
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let pinned = self.expr_ident(span, pinned_ident, pinned_pat_hid);
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let ref_mut_pinned = self.expr_mut_addr_of(span, pinned);
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let task_context = if let Some(task_context_hid) = self.task_context {
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self.expr_ident_mut(span, task_context_ident, task_context_hid)
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} else {
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// Use of `await` outside of an async context, we cannot use `task_context` here.
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self.expr_err(span)
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};
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let pin_ty_id = self.next_id();
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let new_unchecked_expr_kind = self.expr_call_std_assoc_fn(
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pin_ty_id,
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@ -575,14 +618,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
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"new_unchecked",
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arena_vec![self; ref_mut_pinned],
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);
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let new_unchecked =
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self.arena.alloc(self.expr(span, new_unchecked_expr_kind, ThinVec::new()));
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let unsafe_expr = self.expr_unsafe(new_unchecked);
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self.expr_call_std_path(
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let new_unchecked = self.expr(span, new_unchecked_expr_kind, ThinVec::new());
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let call = self.expr_call_std_path(
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gen_future_span,
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&[sym::future, sym::poll_with_tls_context],
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arena_vec![self; unsafe_expr],
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)
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&[sym::future, sym::poll_with_context],
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arena_vec![self; new_unchecked, task_context],
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);
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self.arena.alloc(self.expr_unsafe(call))
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};
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// `::std::task::Poll::Ready(result) => break result`
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@ -629,12 +671,27 @@ impl<'hir> LoweringContext<'_, 'hir> {
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hir::ExprKind::Yield(unit, hir::YieldSource::Await),
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ThinVec::new(),
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);
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self.stmt_expr(span, yield_expr)
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let yield_expr = self.arena.alloc(yield_expr);
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if let Some(task_context_hid) = self.task_context {
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let lhs = self.expr_ident(span, task_context_ident, task_context_hid);
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let assign = self.expr(
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span,
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hir::ExprKind::Assign(lhs, yield_expr, span),
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AttrVec::new(),
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);
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self.stmt_expr(span, assign)
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} else {
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// Use of `await` outside of an async context. Return `yield_expr` so that we can
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// proceed with type checking.
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self.stmt(span, hir::StmtKind::Semi(yield_expr))
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}
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};
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let loop_block = self.block_all(span, arena_vec![self; inner_match_stmt, yield_stmt], None);
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let loop_block =
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self.block_all(span, arena_vec![self; inner_match_stmt, yield_stmt], None);
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// loop { .. }
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// loop { ...; task_context = yield (); }
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let loop_expr = self.arena.alloc(hir::Expr {
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hir_id: loop_hir_id,
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kind: hir::ExprKind::Loop(loop_block, None, hir::LoopSource::Loop),
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@ -809,7 +809,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
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}
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/// Construct `ExprKind::Err` for the given `span`.
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fn expr_err(&mut self, span: Span) -> hir::Expr<'hir> {
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crate fn expr_err(&mut self, span: Span) -> hir::Expr<'hir> {
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self.expr(span, hir::ExprKind::Err, AttrVec::new())
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}
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@ -117,6 +117,10 @@ struct LoweringContext<'a, 'hir: 'a> {
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generator_kind: Option<hir::GeneratorKind>,
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/// When inside an `async` context, this is the `HirId` of the
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/// `task_context` local bound to the resume argument of the generator.
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task_context: Option<hir::HirId>,
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/// Used to get the current `fn`'s def span to point to when using `await`
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/// outside of an `async fn`.
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current_item: Option<Span>,
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@ -295,6 +299,7 @@ pub fn lower_crate<'a, 'hir>(
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item_local_id_counters: Default::default(),
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node_id_to_hir_id: IndexVec::new(),
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generator_kind: None,
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task_context: None,
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current_item: None,
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lifetimes_to_define: Vec::new(),
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is_collecting_in_band_lifetimes: false,
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@ -544,7 +544,7 @@ symbols! {
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plugin_registrar,
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plugins,
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Poll,
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poll_with_tls_context,
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poll_with_context,
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powerpc_target_feature,
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precise_pointer_size_matching,
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pref_align_of,
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@ -720,6 +720,7 @@ symbols! {
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target_has_atomic_load_store,
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target_thread_local,
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task,
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_task_context,
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tbm_target_feature,
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termination_trait,
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termination_trait_test,
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@ -33,10 +33,10 @@ error[E0277]: the trait bound `[closure@$DIR/issue-62009-1.rs:16:5: 16:15]: std:
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LL | (|_| 2333).await;
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| ^^^^^^^^^^^^^^^^ the trait `std::future::Future` is not implemented for `[closure@$DIR/issue-62009-1.rs:16:5: 16:15]`
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::: $SRC_DIR/libstd/future.rs:LL:COL
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::: $SRC_DIR/libcore/future/mod.rs:LL:COL
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LL | F: Future,
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| ------ required by this bound in `std::future::poll_with_tls_context`
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| ------ required by this bound in `std::future::poll_with_context`
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error: aborting due to 4 previous errors
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