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Keep info on pre-desugaring expression for better "incorrect .await" suggestion

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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`.
This commit is contained in:
Esteban Kuber 2021-11-16 20:07:23 +00:00
parent d45e030c04
commit f640438b40
14 changed files with 138 additions and 36 deletions
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51
compiler/rustc_ast_lowering/src/expr.rs
View File

@ -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::HirId>,
) -> 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::HirId>,
) -> &'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::HirId>,
) -> 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,
)
}

11
compiler/rustc_ast_lowering/src/lib.rs
View File

@ -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::HirId>,
) -> &'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))
}

14
compiler/rustc_hir/src/hir.rs
View File

@ -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<HirId>),
}
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,
}
}
}

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

@ -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("\"]");

2
compiler/rustc_lint/src/array_into_iter.rs
View File

@ -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;

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

@ -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<hir::HirId>),
ForLoopIterator,

2
compiler/rustc_save_analysis/src/sig.rs
View File

@ -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, ..) => {

38
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View File

@ -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 => {}

2
compiler/rustc_typeck/src/astconv/mod.rs
View File

@ -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,

7
compiler/rustc_typeck/src/check/expr.rs
View File

@ -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<hir::HirId>,
) -> 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(

3
compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
View File

@ -791,6 +791,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
lang_item: hir::LangItem,
span: Span,
hir_id: hir::HirId,
expr_hir_id: Option<hir::HirId>,
) -> (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
}

4
compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
View File

@ -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)
}
}
}

14
src/test/ui/async-await/unnecessary-await.rs Normal file
View File

@ -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() {}

22
src/test/ui/async-await/unnecessary-await.stderr Normal file
View File

@ -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`.