diff options
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs | 143 |
1 files changed, 81 insertions, 62 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs index 5d0b9dd41b2..99d0a383109 100644 --- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs +++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs @@ -66,71 +66,90 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { let def_id = obligation.predicate.def_id(); let tcx = self.tcx(); - if tcx.is_lang_item(def_id, LangItem::Copy) { - debug!(obligation_self_ty = ?obligation.predicate.skip_binder().self_ty()); - - // User-defined copy impls are permitted, but only for - // structs and enums. - self.assemble_candidates_from_impls(obligation, &mut candidates); - - // For other types, we'll use the builtin rules. - let copy_conditions = self.copy_clone_conditions(obligation); - self.assemble_builtin_bound_candidates(copy_conditions, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::DiscriminantKind) { - // `DiscriminantKind` is automatically implemented for every type. - candidates.vec.push(BuiltinCandidate { has_nested: false }); - } else if tcx.is_lang_item(def_id, LangItem::PointeeTrait) { - // `Pointee` is automatically implemented for every type. - candidates.vec.push(BuiltinCandidate { has_nested: false }); - } else if tcx.is_lang_item(def_id, LangItem::Sized) { - self.assemble_builtin_sized_candidate(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::Unsize) { - self.assemble_candidates_for_unsizing(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::Destruct) { - self.assemble_const_destruct_candidates(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::TransmuteTrait) { - // User-defined transmutability impls are permitted. - self.assemble_candidates_from_impls(obligation, &mut candidates); - self.assemble_candidates_for_transmutability(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::Tuple) { - self.assemble_candidate_for_tuple(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::FnPtrTrait) { - self.assemble_candidates_for_fn_ptr_trait(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::BikeshedGuaranteedNoDrop) { - self.assemble_candidates_for_bikeshed_guaranteed_no_drop_trait( - obligation, - &mut candidates, - ); - } else { - if tcx.is_lang_item(def_id, LangItem::Clone) { - // Same builtin conditions as `Copy`, i.e., every type which has builtin support - // for `Copy` also has builtin support for `Clone`, and tuples/arrays of `Clone` - // types have builtin support for `Clone`. - let clone_conditions = self.copy_clone_conditions(obligation); - self.assemble_builtin_bound_candidates(clone_conditions, &mut candidates); + let lang_item = tcx.as_lang_item(def_id); + match lang_item { + Some(LangItem::Copy | LangItem::Clone) => { + debug!(obligation_self_ty = ?obligation.predicate.skip_binder().self_ty()); + + // User-defined copy impls are permitted, but only for + // structs and enums. + self.assemble_candidates_from_impls(obligation, &mut candidates); + + // For other types, we'll use the builtin rules. + let copy_conditions = self.copy_clone_conditions(obligation); + self.assemble_builtin_bound_candidates(copy_conditions, &mut candidates); } - - if tcx.is_lang_item(def_id, LangItem::Coroutine) { - self.assemble_coroutine_candidates(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::Future) { - self.assemble_future_candidates(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::Iterator) { - self.assemble_iterator_candidates(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::FusedIterator) { - self.assemble_fused_iterator_candidates(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::AsyncIterator) { - self.assemble_async_iterator_candidates(obligation, &mut candidates); - } else if tcx.is_lang_item(def_id, LangItem::AsyncFnKindHelper) { - self.assemble_async_fn_kind_helper_candidates(obligation, &mut candidates); + Some(LangItem::DiscriminantKind) => { + // `DiscriminantKind` is automatically implemented for every type. + candidates.vec.push(BuiltinCandidate { has_nested: false }); } + Some(LangItem::PointeeTrait) => { + // `Pointee` is automatically implemented for every type. + candidates.vec.push(BuiltinCandidate { has_nested: false }); + } + Some(LangItem::Sized) => { + self.assemble_builtin_sized_candidate(obligation, &mut candidates); + } + Some(LangItem::Unsize) => { + self.assemble_candidates_for_unsizing(obligation, &mut candidates); + } + Some(LangItem::Destruct) => { + self.assemble_const_destruct_candidates(obligation, &mut candidates); + } + Some(LangItem::TransmuteTrait) => { + // User-defined transmutability impls are permitted. + self.assemble_candidates_from_impls(obligation, &mut candidates); + self.assemble_candidates_for_transmutability(obligation, &mut candidates); + } + Some(LangItem::Tuple) => { + self.assemble_candidate_for_tuple(obligation, &mut candidates); + } + Some(LangItem::FnPtrTrait) => { + self.assemble_candidates_for_fn_ptr_trait(obligation, &mut candidates); + } + Some(LangItem::BikeshedGuaranteedNoDrop) => { + self.assemble_candidates_for_bikeshed_guaranteed_no_drop_trait( + obligation, + &mut candidates, + ); + } + _ => { + // We re-match here for traits that can have both builtin impls and user written impls. + // After the builtin impls we need to also add user written impls, which we do not want to + // do in general because just checking if there are any is expensive. + match lang_item { + Some(LangItem::Coroutine) => { + self.assemble_coroutine_candidates(obligation, &mut candidates); + } + Some(LangItem::Future) => { + self.assemble_future_candidates(obligation, &mut candidates); + } + Some(LangItem::Iterator) => { + self.assemble_iterator_candidates(obligation, &mut candidates); + } + Some(LangItem::FusedIterator) => { + self.assemble_fused_iterator_candidates(obligation, &mut candidates); + } + Some(LangItem::AsyncIterator) => { + self.assemble_async_iterator_candidates(obligation, &mut candidates); + } + Some(LangItem::AsyncFnKindHelper) => { + self.assemble_async_fn_kind_helper_candidates( + obligation, + &mut candidates, + ); + } + _ => { + // FIXME: Put these into match arms above, since they're built-in. + self.assemble_closure_candidates(obligation, &mut candidates); + self.assemble_async_closure_candidates(obligation, &mut candidates); + self.assemble_fn_pointer_candidates(obligation, &mut candidates); + } + } - // FIXME: Put these into `else if` blocks above, since they're built-in. - self.assemble_closure_candidates(obligation, &mut candidates); - self.assemble_async_closure_candidates(obligation, &mut candidates); - self.assemble_fn_pointer_candidates(obligation, &mut candidates); - - self.assemble_candidates_from_impls(obligation, &mut candidates); - self.assemble_candidates_from_object_ty(obligation, &mut candidates); + self.assemble_candidates_from_impls(obligation, &mut candidates); + self.assemble_candidates_from_object_ty(obligation, &mut candidates); + } } self.assemble_candidates_from_projected_tys(obligation, &mut candidates); |