Prefer lower TraitUpcasting candidates

2025-01-14 17:54:53 +00:00
parent 2ae9916816
commit bf545ce2fe
6 changed files with 54 additions and 6 deletions
--- a/compiler/rustc_trait_selection/src/solve/select.rs
+++ b/compiler/rustc_trait_selection/src/solve/select.rs
@@ -117,6 +117,10 @@ fn candidate_should_be_dropped_in_favor_of<'tcx>(
            CandidateSource::BuiltinImpl(BuiltinImplSource::Object(a)),
            CandidateSource::BuiltinImpl(BuiltinImplSource::Object(b)),
        ) => a >= b,
+        (
+            CandidateSource::BuiltinImpl(BuiltinImplSource::TraitUpcasting(a)),
+            CandidateSource::BuiltinImpl(BuiltinImplSource::TraitUpcasting(b)),
+        ) => a >= b,
        // Prefer dyn candidates over non-dyn candidates. This is necessary to
        // handle the unsoundness between `impl<T: ?Sized> Any for T` and `dyn Any: Any`.
        (