X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=compiler%2Frustc_trait_selection%2Fsrc%2Ftraits%2Ferror_reporting%2Fmod.rs;h=cc61e18743133c94ba0f5951a290937a8516f04d;hb=07fd8089a45cb917ae85eb06e33374db159332e3;hp=56dea916b305f447d03c63cc09016bf058e51f5b;hpb=d1449560e31f7f801d81268a3dad783181656dff;p=rust.git

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 56dea916b30..cc61e187431 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -9,7 +9,7 @@
 };
 use crate::infer::error_reporting::{TyCategory, TypeAnnotationNeeded as ErrorCode};
 use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use crate::infer::{self, InferCtxt, TyCtxtInferExt};
+use crate::infer::{self, InferCtxt};
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
 use crate::traits::query::normalize::QueryNormalizeExt as _;
 use crate::traits::specialize::to_pretty_impl_header;
@@ -1607,7 +1607,7 @@ fn report_projection_error(
                         | ObligationCauseCode::ObjectCastObligation(..)
                         | ObligationCauseCode::OpaqueType
                 );
-                let expected_ty = data.term.ty().unwrap();
+                let expected_ty = data.term.ty().unwrap_or_else(|| self.tcx.ty_error());
 
                 // constrain inference variables a bit more to nested obligations from normalize so
                 // we can have more helpful errors.
@@ -1810,7 +1810,8 @@ fn find_similar_impl_candidates(
         &self,
         trait_pred: ty::PolyTraitPredicate<'tcx>,
     ) -> Vec<ImplCandidate<'tcx>> {
-        self.tcx
+        let mut candidates: Vec<_> = self
+            .tcx
             .all_impls(trait_pred.def_id())
             .filter_map(|def_id| {
                 if self.tcx.impl_polarity(def_id) == ty::ImplPolarity::Negative
@@ -1826,7 +1827,14 @@ fn find_similar_impl_candidates(
                 self.fuzzy_match_tys(trait_pred.skip_binder().self_ty(), imp.self_ty(), false)
                     .map(|similarity| ImplCandidate { trait_ref: imp, similarity })
             })
-            .collect()
+            .collect();
+        if candidates.iter().any(|c| matches!(c.similarity, CandidateSimilarity::Exact { .. })) {
+            // If any of the candidates is a perfect match, we don't want to show all of them.
+            // This is particularly relevant for the case of numeric types (as they all have the
+            // same cathegory).
+            candidates.retain(|c| matches!(c.similarity, CandidateSimilarity::Exact { .. }));
+        }
+        candidates
     }
 
     fn report_similar_impl_candidates(
@@ -1934,14 +1942,6 @@ fn report_similar_impl_candidates(
             return report(normalized_impl_candidates, err);
         }
 
-        let normalize = |candidate| {
-            let infcx = self.tcx.infer_ctxt().build();
-            infcx
-                .at(&ObligationCause::dummy(), ty::ParamEnv::empty())
-                .query_normalize(candidate)
-                .map_or(candidate, |normalized| normalized.value)
-        };
-
         // Sort impl candidates so that ordering is consistent for UI tests.
         // because the ordering of `impl_candidates` may not be deterministic:
         // https://github.com/rust-lang/rust/pull/57475#issuecomment-455519507
@@ -1951,7 +1951,11 @@ fn report_similar_impl_candidates(
         let mut normalized_impl_candidates_and_similarities = impl_candidates
             .into_iter()
             .map(|ImplCandidate { trait_ref, similarity }| {
-                let normalized = normalize(trait_ref);
+                // FIXME(compiler-errors): This should be using `NormalizeExt::normalize`
+                let normalized = self
+                    .at(&ObligationCause::dummy(), ty::ParamEnv::empty())
+                    .query_normalize(trait_ref)
+                    .map_or(trait_ref, |normalized| normalized.value);
                 (similarity, normalized)
             })
             .collect::<Vec<_>>();