lowering: move lower_await -> expr.rs
This commit is contained in:
Mazdak Farrokhzad
parent
548e3090c2
commit
e450dcaf8e
2 changed files with 160 additions and 163 deletions
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@ -5125,168 +5125,6 @@ impl<'a> LoweringContext<'a> {
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ThinVec::new()));
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P(self.expr_call(e.span, from_err, hir_vec![e]))
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}
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fn lower_await(
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&mut self,
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await_span: Span,
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expr: &ast::Expr,
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) -> hir::ExprKind {
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// to:
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//
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// {
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// let mut pinned = <expr>;
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// 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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// ::std::task::Poll::Ready(result) => break result,
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// ::std::task::Poll::Pending => {},
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// }
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// yield ();
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// }
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// }
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match self.generator_kind {
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Some(hir::GeneratorKind::Async) => {},
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Some(hir::GeneratorKind::Gen) |
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None => {
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let mut err = struct_span_err!(
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self.sess,
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await_span,
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E0728,
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"`await` is only allowed inside `async` functions and blocks"
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);
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err.span_label(await_span, "only allowed inside `async` functions and blocks");
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if let Some(item_sp) = self.current_item {
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err.span_label(item_sp, "this is not `async`");
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}
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err.emit();
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}
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}
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let span = self.mark_span_with_reason(
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DesugaringKind::Await,
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await_span,
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None,
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);
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let gen_future_span = self.mark_span_with_reason(
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DesugaringKind::Await,
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await_span,
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self.allow_gen_future.clone(),
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);
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// let mut pinned = <expr>;
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let expr = P(self.lower_expr(expr));
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let pinned_ident = Ident::with_empty_ctxt(sym::pinned);
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let (pinned_pat, pinned_pat_hid) = self.pat_ident_binding_mode(
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span,
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pinned_ident,
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hir::BindingAnnotation::Mutable,
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);
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let pinned_let = self.stmt_let_pat(
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ThinVec::new(),
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span,
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Some(expr),
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pinned_pat,
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hir::LocalSource::AwaitDesugar,
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);
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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 poll_expr = {
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let pinned = P(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 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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span,
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&[sym::pin, sym::Pin],
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"new_unchecked",
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hir_vec![ref_mut_pinned],
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);
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let new_unchecked = P(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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P(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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hir_vec![unsafe_expr],
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))
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};
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// `::std::task::Poll::Ready(result) => break result`
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let loop_node_id = self.sess.next_node_id();
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let loop_hir_id = self.lower_node_id(loop_node_id);
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let ready_arm = {
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let x_ident = Ident::with_empty_ctxt(sym::result);
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let (x_pat, x_pat_hid) = self.pat_ident(span, x_ident);
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let x_expr = P(self.expr_ident(span, x_ident, x_pat_hid));
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let ready_pat = self.pat_std_enum(
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span,
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&[sym::task, sym::Poll, sym::Ready],
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hir_vec![x_pat],
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);
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let break_x = self.with_loop_scope(loop_node_id, |this| {
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let expr_break = hir::ExprKind::Break(
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this.lower_loop_destination(None),
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Some(x_expr),
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);
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P(this.expr(await_span, expr_break, ThinVec::new()))
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});
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self.arm(hir_vec![ready_pat], break_x)
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};
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// `::std::task::Poll::Pending => {}`
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let pending_arm = {
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let pending_pat = self.pat_std_enum(
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span,
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&[sym::task, sym::Poll, sym::Pending],
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hir_vec![],
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);
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let empty_block = P(self.expr_block_empty(span));
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self.arm(hir_vec![pending_pat], empty_block)
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};
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let match_stmt = {
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let match_expr = self.expr_match(
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span,
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poll_expr,
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hir_vec![ready_arm, pending_arm],
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hir::MatchSource::AwaitDesugar,
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);
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self.stmt_expr(span, match_expr)
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};
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let yield_stmt = {
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let unit = self.expr_unit(span);
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let yield_expr = self.expr(
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span,
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hir::ExprKind::Yield(P(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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};
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let loop_block = P(self.block_all(
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span,
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hir_vec![match_stmt, yield_stmt],
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None,
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));
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let loop_expr = P(hir::Expr {
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hir_id: loop_hir_id,
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node: hir::ExprKind::Loop(
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loop_block,
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None,
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hir::LoopSource::Loop,
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),
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span,
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attrs: ThinVec::new(),
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});
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hir::ExprKind::Block(
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P(self.block_all(span, hir_vec![pinned_let], Some(loop_expr))),
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None,
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)
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}
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}
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fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
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@ -263,7 +263,7 @@ impl LoweringContext<'_> {
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})
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})
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}
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ExprKind::Await(ref expr) => self.lower_await(e.span, expr),
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ExprKind::Await(ref expr) => self.lower_expr_await(e.span, expr),
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ExprKind::Closure(
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capture_clause, asyncness, movability, ref decl, ref body, fn_decl_span
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) => if let IsAsync::Async { closure_id, .. } = asyncness {
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@ -375,6 +375,165 @@ impl LoweringContext<'_> {
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}
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}
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/// Desugar `<expr>.await` into:
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/// ```rust
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/// {
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/// let mut pinned = <expr>;
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/// 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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/// ::std::task::Poll::Ready(result) => break result,
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/// ::std::task::Poll::Pending => {},
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/// }
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/// yield ();
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/// }
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/// }
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/// ```
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fn lower_expr_await(&mut self, await_span: Span, expr: &Expr) -> hir::ExprKind {
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match self.generator_kind {
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Some(hir::GeneratorKind::Async) => {},
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Some(hir::GeneratorKind::Gen) |
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None => {
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let mut err = struct_span_err!(
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self.sess,
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await_span,
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E0728,
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"`await` is only allowed inside `async` functions and blocks"
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);
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err.span_label(await_span, "only allowed inside `async` functions and blocks");
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if let Some(item_sp) = self.current_item {
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err.span_label(item_sp, "this is not `async`");
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}
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err.emit();
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}
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}
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let span = self.mark_span_with_reason(
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DesugaringKind::Await,
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await_span,
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None,
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);
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let gen_future_span = self.mark_span_with_reason(
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DesugaringKind::Await,
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await_span,
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self.allow_gen_future.clone(),
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);
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// let mut pinned = <expr>;
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let expr = P(self.lower_expr(expr));
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let pinned_ident = Ident::with_empty_ctxt(sym::pinned);
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let (pinned_pat, pinned_pat_hid) = self.pat_ident_binding_mode(
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span,
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pinned_ident,
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hir::BindingAnnotation::Mutable,
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);
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let pinned_let = self.stmt_let_pat(
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ThinVec::new(),
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span,
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Some(expr),
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pinned_pat,
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hir::LocalSource::AwaitDesugar,
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);
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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 poll_expr = {
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let pinned = P(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 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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span,
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&[sym::pin, sym::Pin],
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"new_unchecked",
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hir_vec![ref_mut_pinned],
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);
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let new_unchecked = P(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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P(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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hir_vec![unsafe_expr],
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))
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};
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// `::std::task::Poll::Ready(result) => break result`
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let loop_node_id = self.sess.next_node_id();
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let loop_hir_id = self.lower_node_id(loop_node_id);
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let ready_arm = {
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let x_ident = Ident::with_empty_ctxt(sym::result);
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let (x_pat, x_pat_hid) = self.pat_ident(span, x_ident);
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let x_expr = P(self.expr_ident(span, x_ident, x_pat_hid));
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let ready_pat = self.pat_std_enum(
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span,
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&[sym::task, sym::Poll, sym::Ready],
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hir_vec![x_pat],
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);
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let break_x = self.with_loop_scope(loop_node_id, |this| {
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let expr_break = hir::ExprKind::Break(
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this.lower_loop_destination(None),
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Some(x_expr),
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);
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P(this.expr(await_span, expr_break, ThinVec::new()))
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});
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self.arm(hir_vec![ready_pat], break_x)
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};
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// `::std::task::Poll::Pending => {}`
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let pending_arm = {
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let pending_pat = self.pat_std_enum(
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span,
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&[sym::task, sym::Poll, sym::Pending],
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hir_vec![],
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);
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let empty_block = P(self.expr_block_empty(span));
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self.arm(hir_vec![pending_pat], empty_block)
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};
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let match_stmt = {
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let match_expr = self.expr_match(
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span,
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poll_expr,
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hir_vec![ready_arm, pending_arm],
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hir::MatchSource::AwaitDesugar,
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);
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self.stmt_expr(span, match_expr)
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};
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let yield_stmt = {
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let unit = self.expr_unit(span);
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let yield_expr = self.expr(
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span,
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hir::ExprKind::Yield(P(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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};
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let loop_block = P(self.block_all(
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span,
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hir_vec![match_stmt, yield_stmt],
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None,
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));
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let loop_expr = P(hir::Expr {
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hir_id: loop_hir_id,
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node: hir::ExprKind::Loop(
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loop_block,
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None,
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hir::LoopSource::Loop,
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),
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span,
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attrs: ThinVec::new(),
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});
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hir::ExprKind::Block(
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P(self.block_all(span, hir_vec![pinned_let], Some(loop_expr))),
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None,
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)
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}
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fn lower_expr_closure(
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&mut self,
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capture_clause: CaptureBy,
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