From f640438b402b6507e734862026b0b004090c8ac0 Mon Sep 17 00:00:00 2001 From: Esteban Kuber Date: Tue, 16 Nov 2021 20:07:23 +0000 Subject: [PATCH] Keep info on pre-desugaring expression for better "incorrect `.await`" suggestion Keep the `HirId` of `.await`ed expressions so in the case of a `fn` call on on a sync `fn`, we can suggest maybe turning it into an `async fn`. --- compiler/rustc_ast_lowering/src/expr.rs | 51 +++++++++++++++---- compiler/rustc_ast_lowering/src/lib.rs | 11 ++-- compiler/rustc_hir/src/hir.rs | 14 ++--- compiler/rustc_hir_pretty/src/lib.rs | 2 +- compiler/rustc_lint/src/array_into_iter.rs | 2 +- compiler/rustc_middle/src/traits/mod.rs | 2 +- compiler/rustc_save_analysis/src/sig.rs | 2 +- .../src/traits/error_reporting/suggestions.rs | 38 +++++++++++++- compiler/rustc_typeck/src/astconv/mod.rs | 2 +- compiler/rustc_typeck/src/check/expr.rs | 7 +-- .../rustc_typeck/src/check/fn_ctxt/_impl.rs | 3 +- .../rustc_typeck/src/check/fn_ctxt/checks.rs | 4 +- src/test/ui/async-await/unnecessary-await.rs | 14 +++++ .../ui/async-await/unnecessary-await.stderr | 22 ++++++++ 14 files changed, 138 insertions(+), 36 deletions(-) create mode 100644 src/test/ui/async-await/unnecessary-await.rs create mode 100644 src/test/ui/async-await/unnecessary-await.stderr diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs index 2cf0dbaf425..16fdd714575 100644 --- a/compiler/rustc_ast_lowering/src/expr.rs +++ b/compiler/rustc_ast_lowering/src/expr.rs @@ -479,8 +479,12 @@ impl<'hir> LoweringContext<'_, 'hir> { expr: &'hir hir::Expr<'hir>, overall_span: Span, ) -> &'hir hir::Expr<'hir> { - let constructor = - self.arena.alloc(self.expr_lang_item_path(method_span, lang_item, ThinVec::new())); + let constructor = self.arena.alloc(self.expr_lang_item_path( + method_span, + lang_item, + ThinVec::new(), + None, + )); self.expr_call(overall_span, constructor, std::slice::from_ref(expr)) } @@ -584,8 +588,12 @@ impl<'hir> LoweringContext<'_, 'hir> { // `future::from_generator`: let unstable_span = self.mark_span_with_reason(DesugaringKind::Async, span, self.allow_gen_future.clone()); - let gen_future = - self.expr_lang_item_path(unstable_span, hir::LangItem::FromGenerator, ThinVec::new()); + let gen_future = self.expr_lang_item_path( + unstable_span, + hir::LangItem::FromGenerator, + ThinVec::new(), + None, + ); // `future::from_generator(generator)`: hir::ExprKind::Call(self.arena.alloc(gen_future), arena_vec![self; generator]) @@ -657,16 +665,19 @@ impl<'hir> LoweringContext<'_, 'hir> { span, hir::LangItem::PinNewUnchecked, arena_vec![self; ref_mut_pinned], + Some(expr.hir_id), ); let get_context = self.expr_call_lang_item_fn_mut( gen_future_span, hir::LangItem::GetContext, arena_vec![self; task_context], + Some(expr.hir_id), ); let call = self.expr_call_lang_item_fn( span, hir::LangItem::FuturePoll, arena_vec![self; new_unchecked, get_context], + Some(expr.hir_id), ); self.arena.alloc(self.expr_unsafe(call)) }; @@ -679,7 +690,12 @@ impl<'hir> LoweringContext<'_, 'hir> { let (x_pat, x_pat_hid) = self.pat_ident(span, x_ident); let x_expr = self.expr_ident(span, x_ident, x_pat_hid); let ready_field = self.single_pat_field(span, x_pat); - let ready_pat = self.pat_lang_item_variant(span, hir::LangItem::PollReady, ready_field); + let ready_pat = self.pat_lang_item_variant( + span, + hir::LangItem::PollReady, + ready_field, + Some(expr.hir_id), + ); let break_x = self.with_loop_scope(loop_node_id, move |this| { let expr_break = hir::ExprKind::Break(this.lower_loop_destination(None), Some(x_expr)); @@ -690,7 +706,12 @@ impl<'hir> LoweringContext<'_, 'hir> { // `::std::task::Poll::Pending => {}` let pending_arm = { - let pending_pat = self.pat_lang_item_variant(span, hir::LangItem::PollPending, &[]); + let pending_pat = self.pat_lang_item_variant( + span, + hir::LangItem::PollPending, + &[], + Some(expr.hir_id), + ); let empty_block = self.expr_block_empty(span); self.arm(pending_pat, empty_block) }; @@ -1161,7 +1182,8 @@ impl<'hir> LoweringContext<'_, 'hir> { fn lower_expr_range_closed(&mut self, span: Span, e1: &Expr, e2: &Expr) -> hir::ExprKind<'hir> { let e1 = self.lower_expr_mut(e1); let e2 = self.lower_expr_mut(e2); - let fn_path = hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, self.lower_span(span)); + let fn_path = + hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, self.lower_span(span), None); let fn_expr = self.arena.alloc(self.expr(span, hir::ExprKind::Path(fn_path), ThinVec::new())); hir::ExprKind::Call(fn_expr, arena_vec![self; e1, e2]) @@ -1195,7 +1217,7 @@ impl<'hir> LoweringContext<'_, 'hir> { ); hir::ExprKind::Struct( - self.arena.alloc(hir::QPath::LangItem(lang_item, self.lower_span(span))), + self.arena.alloc(hir::QPath::LangItem(lang_item, self.lower_span(span), None)), fields, None, ) @@ -1390,6 +1412,7 @@ impl<'hir> LoweringContext<'_, 'hir> { head_span, hir::LangItem::IteratorNext, arena_vec![self; ref_mut_iter], + None, ); let arms = arena_vec![self; none_arm, some_arm]; @@ -1418,6 +1441,7 @@ impl<'hir> LoweringContext<'_, 'hir> { head_span, hir::LangItem::IntoIterIntoIter, arena_vec![self; head], + None, ) }; @@ -1473,6 +1497,7 @@ impl<'hir> LoweringContext<'_, 'hir> { unstable_span, hir::LangItem::TryTraitBranch, arena_vec![self; sub_expr], + None, ) }; @@ -1629,8 +1654,10 @@ impl<'hir> LoweringContext<'_, 'hir> { span: Span, lang_item: hir::LangItem, args: &'hir [hir::Expr<'hir>], + hir_id: Option, ) -> hir::Expr<'hir> { - let path = self.arena.alloc(self.expr_lang_item_path(span, lang_item, ThinVec::new())); + let path = + self.arena.alloc(self.expr_lang_item_path(span, lang_item, ThinVec::new(), hir_id)); self.expr_call_mut(span, path, args) } @@ -1639,8 +1666,9 @@ impl<'hir> LoweringContext<'_, 'hir> { span: Span, lang_item: hir::LangItem, args: &'hir [hir::Expr<'hir>], + hir_id: Option, ) -> &'hir hir::Expr<'hir> { - self.arena.alloc(self.expr_call_lang_item_fn_mut(span, lang_item, args)) + self.arena.alloc(self.expr_call_lang_item_fn_mut(span, lang_item, args, hir_id)) } fn expr_lang_item_path( @@ -1648,10 +1676,11 @@ impl<'hir> LoweringContext<'_, 'hir> { span: Span, lang_item: hir::LangItem, attrs: AttrVec, + hir_id: Option, ) -> hir::Expr<'hir> { self.expr( span, - hir::ExprKind::Path(hir::QPath::LangItem(lang_item, self.lower_span(span))), + hir::ExprKind::Path(hir::QPath::LangItem(lang_item, self.lower_span(span), hir_id)), attrs, ) } diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs index c04b0471cb7..e03e82b2b77 100644 --- a/compiler/rustc_ast_lowering/src/lib.rs +++ b/compiler/rustc_ast_lowering/src/lib.rs @@ -2127,21 +2127,21 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { fn pat_cf_continue(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> { let field = self.single_pat_field(span, pat); - self.pat_lang_item_variant(span, hir::LangItem::ControlFlowContinue, field) + self.pat_lang_item_variant(span, hir::LangItem::ControlFlowContinue, field, None) } fn pat_cf_break(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> { let field = self.single_pat_field(span, pat); - self.pat_lang_item_variant(span, hir::LangItem::ControlFlowBreak, field) + self.pat_lang_item_variant(span, hir::LangItem::ControlFlowBreak, field, None) } fn pat_some(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> { let field = self.single_pat_field(span, pat); - self.pat_lang_item_variant(span, hir::LangItem::OptionSome, field) + self.pat_lang_item_variant(span, hir::LangItem::OptionSome, field, None) } fn pat_none(&mut self, span: Span) -> &'hir hir::Pat<'hir> { - self.pat_lang_item_variant(span, hir::LangItem::OptionNone, &[]) + self.pat_lang_item_variant(span, hir::LangItem::OptionNone, &[], None) } fn single_pat_field( @@ -2164,8 +2164,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { span: Span, lang_item: hir::LangItem, fields: &'hir [hir::PatField<'hir>], + hir_id: Option, ) -> &'hir hir::Pat<'hir> { - let qpath = hir::QPath::LangItem(lang_item, self.lower_span(span)); + let qpath = hir::QPath::LangItem(lang_item, self.lower_span(span), hir_id); self.pat(span, hir::PatKind::Struct(qpath, fields, false)) } diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs index fdf7a8102a0..01d95f71c9b 100644 --- a/compiler/rustc_hir/src/hir.rs +++ b/compiler/rustc_hir/src/hir.rs @@ -1627,13 +1627,13 @@ pub fn is_range_literal(expr: &Expr<'_>) -> bool { | LangItem::RangeFrom | LangItem::RangeFull | LangItem::RangeToInclusive, - _, + .. ) ), // `..=` desugars into `::std::ops::RangeInclusive::new(...)`. ExprKind::Call(ref func, _) => { - matches!(func.kind, ExprKind::Path(QPath::LangItem(LangItem::RangeInclusiveNew, _))) + matches!(func.kind, ExprKind::Path(QPath::LangItem(LangItem::RangeInclusiveNew, ..))) } _ => false, @@ -1788,8 +1788,8 @@ pub enum QPath<'hir> { /// the `X` and `Y` nodes each being a `TyKind::Path(QPath::TypeRelative(..))`. TypeRelative(&'hir Ty<'hir>, &'hir PathSegment<'hir>), - /// Reference to a `#[lang = "foo"]` item. - LangItem(LangItem, Span), + /// Reference to a `#[lang = "foo"]` item. `HirId` of the inner expr. + LangItem(LangItem, Span, Option), } impl<'hir> QPath<'hir> { @@ -1798,7 +1798,7 @@ impl<'hir> QPath<'hir> { match *self { QPath::Resolved(_, path) => path.span, QPath::TypeRelative(qself, ps) => qself.span.to(ps.ident.span), - QPath::LangItem(_, span) => span, + QPath::LangItem(_, span, _) => span, } } @@ -1808,7 +1808,7 @@ impl<'hir> QPath<'hir> { match *self { QPath::Resolved(_, path) => path.span, QPath::TypeRelative(qself, _) => qself.span, - QPath::LangItem(_, span) => span, + QPath::LangItem(_, span, _) => span, } } @@ -1818,7 +1818,7 @@ impl<'hir> QPath<'hir> { match *self { QPath::Resolved(_, path) => path.segments.last().unwrap().ident.span, QPath::TypeRelative(_, segment) => segment.ident.span, - QPath::LangItem(_, span) => span, + QPath::LangItem(_, span, _) => span, } } } diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs index 65cdf10f901..389e3845c56 100644 --- a/compiler/rustc_hir_pretty/src/lib.rs +++ b/compiler/rustc_hir_pretty/src/lib.rs @@ -1731,7 +1731,7 @@ impl<'a> State<'a> { colons_before_params, ) } - hir::QPath::LangItem(lang_item, span) => { + hir::QPath::LangItem(lang_item, span, _) => { self.word("#[lang = \""); self.print_ident(Ident::new(lang_item.name(), span)); self.word("\"]"); diff --git a/compiler/rustc_lint/src/array_into_iter.rs b/compiler/rustc_lint/src/array_into_iter.rs index 4a24f803e84..b6151757588 100644 --- a/compiler/rustc_lint/src/array_into_iter.rs +++ b/compiler/rustc_lint/src/array_into_iter.rs @@ -52,7 +52,7 @@ impl<'tcx> LateLintPass<'tcx> for ArrayIntoIter { if let hir::ExprKind::Call(path, [arg]) = &arg.kind { if let hir::ExprKind::Path(hir::QPath::LangItem( hir::LangItem::IntoIterIntoIter, - _, + .., )) = &path.kind { self.for_expr_span = arg.span; diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs index 079899ac494..a5bd246712b 100644 --- a/compiler/rustc_middle/src/traits/mod.rs +++ b/compiler/rustc_middle/src/traits/mod.rs @@ -348,7 +348,7 @@ pub enum ObligationCauseCode<'tcx> { /// If `X` is the concrete type of an opaque type `impl Y`, then `X` must implement `Y` OpaqueType, - AwaitableExpr, + AwaitableExpr(Option), ForLoopIterator, diff --git a/compiler/rustc_save_analysis/src/sig.rs b/compiler/rustc_save_analysis/src/sig.rs index 7864b47ab0a..1d9c44bffa3 100644 --- a/compiler/rustc_save_analysis/src/sig.rs +++ b/compiler/rustc_save_analysis/src/sig.rs @@ -286,7 +286,7 @@ impl<'hir> Sig for hir::Ty<'hir> { refs: vec![SigElement { id, start, end }], }) } - hir::TyKind::Path(hir::QPath::LangItem(lang_item, _)) => { + hir::TyKind::Path(hir::QPath::LangItem(lang_item, _, _)) => { Ok(text_sig(format!("#[lang = \"{}\"]", lang_item.name()))) } hir::TyKind::TraitObject(bounds, ..) => { diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index 9893e5143fc..ede8511d815 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -886,7 +886,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { ) { let span = obligation.cause.span; - if let ObligationCauseCode::AwaitableExpr = obligation.cause.code { + if let ObligationCauseCode::AwaitableExpr(hir_id) = obligation.cause.code { // FIXME: use `obligation.predicate.kind()...trait_ref.self_ty()` to see if we have `()` // and if not maybe suggest doing something else? If we kept the expression around we // could also check if it is an fn call (very likely) and suggest changing *that*, if @@ -897,6 +897,40 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { String::new(), Applicability::MachineApplicable, ); + // FIXME: account for associated `async fn`s. + let hir = self.tcx.hir(); + if let Some(node) = hir_id.and_then(|hir_id| hir.find(hir_id)) { + if let hir::Node::Expr(hir::Expr { + span, kind: hir::ExprKind::Call(base, _), .. + }) = node + { + if let ty::PredicateKind::Trait(pred) = + obligation.predicate.kind().skip_binder() + { + err.span_label(*span, &format!("this call returns `{}`", pred.self_ty())); + } + if let Some(typeck_results) = + self.in_progress_typeck_results.map(|t| t.borrow()) + { + let ty = typeck_results.expr_ty_adjusted(base); + if let ty::FnDef(def_id, _substs) = ty.kind() { + if let Some(hir::Node::Item(hir::Item { span, ident, .. })) = + hir.get_if_local(*def_id) + { + err.span_suggestion_verbose( + span.shrink_to_lo(), + &format!( + "alternatively, consider making `fn {}` asynchronous", + ident + ), + "async ".to_string(), + Applicability::MaybeIncorrect, + ); + } + } + } + } + } } } @@ -1962,7 +1996,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { | ObligationCauseCode::ReturnType | ObligationCauseCode::ReturnValue(_) | ObligationCauseCode::BlockTailExpression(_) - | ObligationCauseCode::AwaitableExpr + | ObligationCauseCode::AwaitableExpr(_) | ObligationCauseCode::ForLoopIterator | ObligationCauseCode::QuestionMark | ObligationCauseCode::LetElse => {} diff --git a/compiler/rustc_typeck/src/astconv/mod.rs b/compiler/rustc_typeck/src/astconv/mod.rs index 752183365d6..8a44874bb47 100644 --- a/compiler/rustc_typeck/src/astconv/mod.rs +++ b/compiler/rustc_typeck/src/astconv/mod.rs @@ -2362,7 +2362,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { .map(|(ty, _, _)| ty) .unwrap_or_else(|_| tcx.ty_error()) } - hir::TyKind::Path(hir::QPath::LangItem(lang_item, span)) => { + hir::TyKind::Path(hir::QPath::LangItem(lang_item, span, _)) => { let def_id = tcx.require_lang_item(lang_item, Some(span)); let (substs, _) = self.create_substs_for_ast_path( span, diff --git a/compiler/rustc_typeck/src/check/expr.rs b/compiler/rustc_typeck/src/check/expr.rs index 311106474be..bc6ad3c9686 100644 --- a/compiler/rustc_typeck/src/check/expr.rs +++ b/compiler/rustc_typeck/src/check/expr.rs @@ -277,8 +277,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { ExprKind::AddrOf(kind, mutbl, oprnd) => { self.check_expr_addr_of(kind, mutbl, oprnd, expected, expr) } - ExprKind::Path(QPath::LangItem(lang_item, _)) => { - self.check_lang_item_path(lang_item, expr) + ExprKind::Path(QPath::LangItem(lang_item, _, hir_id)) => { + self.check_lang_item_path(lang_item, expr, hir_id) } ExprKind::Path(ref qpath) => self.check_expr_path(qpath, expr, &[]), ExprKind::InlineAsm(asm) => self.check_expr_asm(asm), @@ -498,8 +498,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { &self, lang_item: hir::LangItem, expr: &'tcx hir::Expr<'tcx>, + hir_id: Option, ) -> Ty<'tcx> { - self.resolve_lang_item_path(lang_item, expr.span, expr.hir_id).1 + self.resolve_lang_item_path(lang_item, expr.span, expr.hir_id, hir_id).1 } pub(crate) fn check_expr_path( diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs index b437d4c5c2e..ab2d5286907 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs @@ -791,6 +791,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { lang_item: hir::LangItem, span: Span, hir_id: hir::HirId, + expr_hir_id: Option, ) -> (Res, Ty<'tcx>) { let def_id = self.tcx.require_lang_item(lang_item, Some(span)); let def_kind = self.tcx.def_kind(def_id); @@ -809,7 +810,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { def_id, &substs, match lang_item { - hir::LangItem::FuturePoll => ObligationCauseCode::AwaitableExpr, + hir::LangItem::FuturePoll => ObligationCauseCode::AwaitableExpr(expr_hir_id), hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => { ObligationCauseCode::ForLoopIterator } diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs index 4cb597cb6d6..b2641726075 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs @@ -938,8 +938,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { (result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)), ty) } - QPath::LangItem(lang_item, span) => { - self.resolve_lang_item_path(lang_item, span, hir_id) + QPath::LangItem(lang_item, span, id) => { + self.resolve_lang_item_path(lang_item, span, hir_id, id) } } } diff --git a/src/test/ui/async-await/unnecessary-await.rs b/src/test/ui/async-await/unnecessary-await.rs new file mode 100644 index 00000000000..70c38aaeb25 --- /dev/null +++ b/src/test/ui/async-await/unnecessary-await.rs @@ -0,0 +1,14 @@ +// edition:2018 + +async fn foo () { } +fn bar () -> impl std::future::Future { async {} } +fn boo () {} + +async fn baz() -> std::io::Result<()> { + foo().await; + boo().await; //~ ERROR `()` is not a future + bar().await; + std::io::Result::Ok(()) +} + +fn main() {} \ No newline at end of file diff --git a/src/test/ui/async-await/unnecessary-await.stderr b/src/test/ui/async-await/unnecessary-await.stderr new file mode 100644 index 00000000000..4caa15e67b7 --- /dev/null +++ b/src/test/ui/async-await/unnecessary-await.stderr @@ -0,0 +1,22 @@ +error[E0277]: `()` is not a future + --> $DIR/unnecessary-await.rs:9:10 + | +LL | boo().await; + | -----^^^^^^ `()` is not a future + | | + | this call returns `()` + | + = help: the trait `Future` is not implemented for `()` +help: do not `.await` the expression + | +LL - boo().await; +LL + boo(); + | +help: alternatively, consider making `fn boo` asynchronous + | +LL | async fn boo () {} + | +++++ + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`.