bjoernager/rust
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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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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 => {}