diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs')
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs | 90 |
1 files changed, 66 insertions, 24 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 f4b6d3bcf..38b1046ac 100644 --- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs +++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs @@ -115,6 +115,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { self.assemble_future_candidates(obligation, &mut candidates); } else if lang_items.iterator_trait() == Some(def_id) { self.assemble_iterator_candidates(obligation, &mut candidates); + } else if lang_items.async_iterator_trait() == Some(def_id) { + self.assemble_async_iterator_candidates(obligation, &mut candidates); } self.assemble_closure_candidates(obligation, &mut candidates); @@ -155,10 +157,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { .infcx .probe(|_| self.match_projection_obligation_against_definition_bounds(obligation)); - // FIXME(effects) proper constness needed? - candidates.vec.extend( - result.into_iter().map(|idx| ProjectionCandidate(idx, ty::BoundConstness::NotConst)), - ); + candidates.vec.extend(result.into_iter().map(|idx| ProjectionCandidate(idx))); } /// Given an obligation like `<SomeTrait for T>`, searches the obligations that the caller @@ -261,6 +260,34 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { } } + fn assemble_async_iterator_candidates( + &mut self, + obligation: &PolyTraitObligation<'tcx>, + candidates: &mut SelectionCandidateSet<'tcx>, + ) { + let self_ty = obligation.self_ty().skip_binder(); + if let ty::Coroutine(did, args, _) = *self_ty.kind() { + // gen constructs get lowered to a special kind of coroutine that + // should directly `impl AsyncIterator`. + if self.tcx().coroutine_is_async_gen(did) { + debug!(?self_ty, ?obligation, "assemble_iterator_candidates",); + + // Can only confirm this candidate if we have constrained + // the `Yield` type to at least `Poll<Option<?0>>`.. + let ty::Adt(_poll_def, args) = *args.as_coroutine().yield_ty().kind() else { + candidates.ambiguous = true; + return; + }; + let ty::Adt(_option_def, _) = *args.type_at(0).kind() else { + candidates.ambiguous = true; + return; + }; + + candidates.vec.push(AsyncIteratorCandidate); + } + } + } + /// Checks for the artificial impl that the compiler will create for an obligation like `X : /// FnMut<..>` where `X` is a closure type. /// @@ -291,8 +318,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { } } None => { - debug!("assemble_unboxed_candidates: closure_kind not yet known"); - candidates.vec.push(ClosureCandidate { is_const }); + if kind == ty::ClosureKind::FnOnce { + candidates.vec.push(ClosureCandidate { is_const }); + } else { + candidates.ambiguous = true; + } } } } @@ -328,17 +358,23 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { // Provide an impl, but only for suitable `fn` pointers. ty::FnPtr(sig) => { if sig.is_fn_trait_compatible() { - candidates.vec.push(FnPointerCandidate { is_const: false }); + candidates + .vec + .push(FnPointerCandidate { fn_host_effect: self.tcx().consts.true_ }); } } // Provide an impl for suitable functions, rejecting `#[target_feature]` functions (RFC 2396). - ty::FnDef(def_id, _) => { - if self.tcx().fn_sig(def_id).skip_binder().is_fn_trait_compatible() - && self.tcx().codegen_fn_attrs(def_id).target_features.is_empty() + ty::FnDef(def_id, args) => { + let tcx = self.tcx(); + if tcx.fn_sig(def_id).skip_binder().is_fn_trait_compatible() + && tcx.codegen_fn_attrs(def_id).target_features.is_empty() { - candidates - .vec - .push(FnPointerCandidate { is_const: self.tcx().is_const_fn(def_id) }); + candidates.vec.push(FnPointerCandidate { + fn_host_effect: tcx + .generics_of(def_id) + .host_effect_index + .map_or(tcx.consts.true_, |idx| args.const_at(idx)), + }); } } _ => {} @@ -375,7 +411,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { // consider a "quick reject". This avoids creating more types // and so forth that we need to. let impl_trait_ref = self.tcx().impl_trait_ref(impl_def_id).unwrap(); - if !drcx.args_refs_may_unify(obligation_args, impl_trait_ref.skip_binder().args) { + if !drcx.args_may_unify(obligation_args, impl_trait_ref.skip_binder().args) { return; } if self.reject_fn_ptr_impls( @@ -555,7 +591,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { } ty::Alias(ty::Opaque, _) => { - if candidates.vec.iter().any(|c| matches!(c, ProjectionCandidate(..))) { + if candidates.vec.iter().any(|c| matches!(c, ProjectionCandidate(_))) { // We do not generate an auto impl candidate for `impl Trait`s which already // reference our auto trait. // @@ -634,7 +670,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { let self_ty = placeholder_trait_predicate.self_ty(); let principal_trait_ref = match self_ty.kind() { - ty::Dynamic(ref data, ..) => { + ty::Dynamic(data, ..) => { if data.auto_traits().any(|did| did == obligation.predicate.def_id()) { debug!( "assemble_candidates_from_object_ty: matched builtin bound, \ @@ -759,10 +795,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { match (source.kind(), target.kind()) { // Trait+Kx+'a -> Trait+Ky+'b (upcasts). - ( - &ty::Dynamic(ref a_data, a_region, ty::Dyn), - &ty::Dynamic(ref b_data, b_region, ty::Dyn), - ) => { + (&ty::Dynamic(a_data, a_region, ty::Dyn), &ty::Dynamic(b_data, b_region, ty::Dyn)) => { // Upcast coercions permit several things: // // 1. Dropping auto traits, e.g., `Foo + Send` to `Foo` @@ -923,9 +956,18 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { ) { // If the predicate is `~const Destruct` in a non-const environment, we don't actually need // to check anything. We'll short-circuit checking any obligations in confirmation, too. - // FIXME(effects) - if true { - candidates.vec.push(ConstDestructCandidate(None)); + let Some(host_effect_index) = + self.tcx().generics_of(obligation.predicate.def_id()).host_effect_index + else { + candidates.vec.push(BuiltinCandidate { has_nested: false }); + return; + }; + // If the obligation has `host = true`, then the obligation is non-const and it's always + // trivially implemented. + if obligation.predicate.skip_binder().trait_ref.args.const_at(host_effect_index) + == self.tcx().consts.true_ + { + candidates.vec.push(BuiltinCandidate { has_nested: false }); return; } @@ -1051,7 +1093,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { ) { // The regions of a type don't affect the size of the type let tcx = self.tcx(); - let self_ty = tcx.erase_late_bound_regions(obligation.predicate.self_ty()); + let self_ty = tcx.instantiate_bound_regions_with_erased(obligation.predicate.self_ty()); // We should erase regions from both the param-env and type, since both // may have infer regions. Specifically, after canonicalizing and instantiating, // early bound regions turn into region vars in both the new and old solver. |