diff options
4 files changed, 55 insertions, 7 deletions
diff --git a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs index aaab89ace0a..bd43d3c01e2 100644 --- a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs +++ b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs @@ -429,6 +429,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> { body_id: Option<hir::BodyId>, span: Span, arg: GenericArg<'tcx>, + impl_candidates: Vec<ty::TraitRef<'tcx>>, error_code: TypeAnnotationNeeded, ) -> DiagnosticBuilder<'tcx> { let arg = self.resolve_vars_if_possible(arg); @@ -653,7 +654,44 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> { }; err.span_label(pattern.span, msg); } else if let Some(e) = local_visitor.found_method_call { - if let ExprKind::MethodCall(segment, ..) = &e.kind { + if let ExprKind::MethodCall(segment, _, exprs, _) = &e.kind { + // Suggest impl candidates: + // + // error[E0283]: type annotations needed + // --> $DIR/E0283.rs:35:24 + // | + // LL | let bar = foo_impl.into() * 1u32; + // | ---------^^^^-- + // | | | + // | | cannot infer type for type parameter `T` declared on the trait `Into` + // | this method call resolves to `T` + // | help: specify type like: `<Impl as Into<u32>>::into(foo_impl)` + // | + // = note: cannot satisfy `Impl: Into<_>` + if !impl_candidates.is_empty() && e.span.contains(span) { + if let Some(expr) = exprs.first() { + if let ExprKind::Path(hir::QPath::Resolved(_, path)) = expr.kind { + if let [path_segment] = &path.segments[..] { + let candidate_len = impl_candidates.len(); + let suggestions = impl_candidates.iter().map(|candidate| { + format!( + "{}::{}({})", + candidate, segment.ident, path_segment.ident + ) + }); + err.span_suggestions( + e.span, + &format!( + "use the fully qualified path for the potential candidate{}", + pluralize!(candidate_len), + ), + suggestions, + Applicability::MaybeIncorrect, + ); + } + } + }; + } // Suggest specifying type params or point out the return type of the call: // // error[E0282]: type annotations needed diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs index 3eeb5038f36..a42a05c5f02 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs @@ -1498,11 +1498,18 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> { // check upstream for type errors and don't add the obligations to // begin with in those cases. if self.tcx.lang_items().sized_trait() == Some(trait_ref.def_id()) { - self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0282).emit(); + self.emit_inference_failure_err(body_id, span, subst, vec![], ErrorCode::E0282) + .emit(); return; } - let mut err = - self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0283); + let impl_candidates = self.find_similar_impl_candidates(trait_ref); + let mut err = self.emit_inference_failure_err( + body_id, + span, + subst, + impl_candidates, + ErrorCode::E0283, + ); err.note(&format!("cannot satisfy `{}`", predicate)); if let ObligationCauseCode::ItemObligation(def_id) = obligation.cause.code { self.suggest_fully_qualified_path(&mut err, def_id, span, trait_ref.def_id()); @@ -1566,7 +1573,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> { return; } - self.emit_inference_failure_err(body_id, span, arg, ErrorCode::E0282) + self.emit_inference_failure_err(body_id, span, arg, vec![], ErrorCode::E0282) } ty::PredicateKind::Subtype(data) => { @@ -1577,7 +1584,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> { let SubtypePredicate { a_is_expected: _, a, b } = data; // both must be type variables, or the other would've been instantiated assert!(a.is_ty_var() && b.is_ty_var()); - self.emit_inference_failure_err(body_id, span, a.into(), ErrorCode::E0282) + self.emit_inference_failure_err(body_id, span, a.into(), vec![], ErrorCode::E0282) } ty::PredicateKind::Projection(data) => { let trait_ref = bound_predicate.rebind(data).to_poly_trait_ref(self.tcx); @@ -1592,6 +1599,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> { body_id, span, self_ty.into(), + vec![], ErrorCode::E0284, ); err.note(&format!("cannot satisfy `{}`", predicate)); diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs index 5a372c0aaab..c491ba30841 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs @@ -1479,7 +1479,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { ty } else { if !self.is_tainted_by_errors() { - self.emit_inference_failure_err((**self).body_id, sp, ty.into(), E0282) + self.emit_inference_failure_err((**self).body_id, sp, ty.into(), vec![], E0282) .note("type must be known at this point") .emit(); } diff --git a/compiler/rustc_typeck/src/check/writeback.rs b/compiler/rustc_typeck/src/check/writeback.rs index 6edce62f76b..9e6bf5ce52d 100644 --- a/compiler/rustc_typeck/src/check/writeback.rs +++ b/compiler/rustc_typeck/src/check/writeback.rs @@ -694,6 +694,7 @@ impl<'cx, 'tcx> Resolver<'cx, 'tcx> { Some(self.body.id()), self.span.to_span(self.tcx), t.into(), + vec![], E0282, ) .emit(); @@ -707,6 +708,7 @@ impl<'cx, 'tcx> Resolver<'cx, 'tcx> { Some(self.body.id()), self.span.to_span(self.tcx), c.into(), + vec![], E0282, ) .emit(); |