diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src')
3 files changed, 17 insertions, 1 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/select.rs b/compiler/rustc_trait_selection/src/solve/select.rs index 1661852903c..b0b6274907d 100644 --- 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`. ( diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs index 3619d16cde2..0ccb0fc0615 100644 --- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs +++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs @@ -1090,7 +1090,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { )? .expect("did not expect ambiguity during confirmation"); - Ok(ImplSource::Builtin(BuiltinImplSource::TraitUpcasting, nested)) + Ok(ImplSource::Builtin(BuiltinImplSource::TraitUpcasting(idx), nested)) } fn confirm_builtin_unsize_candidate( diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index 9e7da5eb368..5581ea46882 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -1895,6 +1895,18 @@ impl<'tcx> SelectionContext<'_, 'tcx> { Some(None) => {} None => return None, } + // Same for upcasting. + let upcast_bound = candidates + .iter() + .filter_map(|c| { + if let TraitUpcastingUnsizeCandidate(i) = c.candidate { Some(i) } else { None } + }) + .try_reduce(|c1, c2| if has_non_region_infer { None } else { Some(c1.min(c2)) }); + match upcast_bound { + Some(Some(index)) => return Some(TraitUpcastingUnsizeCandidate(index)), + Some(None) => {} + None => return None, + } // Finally, handle overlapping user-written impls. let impls = candidates.iter().filter_map(|c| { |