diff options
Diffstat (limited to 'compiler/rustc_ty_utils/src/implied_bounds.rs')
| -rw-r--r-- | compiler/rustc_ty_utils/src/implied_bounds.rs | 92 |
1 files changed, 83 insertions, 9 deletions
diff --git a/compiler/rustc_ty_utils/src/implied_bounds.rs b/compiler/rustc_ty_utils/src/implied_bounds.rs index 10dec9a7a..436f10a4f 100644 --- a/compiler/rustc_ty_utils/src/implied_bounds.rs +++ b/compiler/rustc_ty_utils/src/implied_bounds.rs @@ -1,3 +1,4 @@ +use rustc_data_structures::fx::FxHashMap; use rustc_hir as hir; use rustc_hir::def::DefKind; use rustc_hir::def_id::LocalDefId; @@ -7,13 +8,20 @@ use rustc_span::Span; use std::iter; pub fn provide(providers: &mut Providers) { - *providers = Providers { assumed_wf_types, ..*providers }; + *providers = Providers { + assumed_wf_types, + assumed_wf_types_for_rpitit: |tcx, def_id| { + assert!(tcx.is_impl_trait_in_trait(def_id.to_def_id())); + tcx.assumed_wf_types(def_id) + }, + ..*providers + }; } fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<'tcx>, Span)] { match tcx.def_kind(def_id) { DefKind::Fn => { - let sig = tcx.fn_sig(def_id).subst_identity(); + let sig = tcx.fn_sig(def_id).instantiate_identity(); let liberated_sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), sig); tcx.arena.alloc_from_iter(itertools::zip_eq( liberated_sig.inputs_and_output, @@ -21,7 +29,7 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<' )) } DefKind::AssocFn => { - let sig = tcx.fn_sig(def_id).subst_identity(); + let sig = tcx.fn_sig(def_id).instantiate_identity(); let liberated_sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), sig); let mut assumed_wf_types: Vec<_> = tcx.assumed_wf_types(tcx.local_parent(def_id)).into(); @@ -35,23 +43,90 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<' // Trait arguments and the self type for trait impls or only the self type for // inherent impls. let tys = match tcx.impl_trait_ref(def_id) { - Some(trait_ref) => trait_ref.skip_binder().substs.types().collect(), - None => vec![tcx.type_of(def_id).subst_identity()], + Some(trait_ref) => trait_ref.skip_binder().args.types().collect(), + None => vec![tcx.type_of(def_id).instantiate_identity()], }; let mut impl_spans = impl_spans(tcx, def_id); tcx.arena.alloc_from_iter(tys.into_iter().map(|ty| (ty, impl_spans.next().unwrap()))) } + DefKind::AssocTy if let Some(data) = tcx.opt_rpitit_info(def_id.to_def_id()) => match data { + ty::ImplTraitInTraitData::Trait { fn_def_id, .. } => { + // We need to remap all of the late-bound lifetimes in theassumed wf types + // of the fn (which are represented as ReFree) to the early-bound lifetimes + // of the RPITIT (which are represented by ReEarlyBound owned by the opaque). + // Luckily, this is very easy to do because we already have that mapping + // stored in the HIR of this RPITIT. + // + // Side-note: We don't really need to do this remapping for early-bound + // lifetimes because they're already "linked" by the bidirectional outlives + // predicates we insert in the `explicit_predicates_of` query for RPITITs. + let mut mapping = FxHashMap::default(); + let generics = tcx.generics_of(def_id); + + // For each captured opaque lifetime, if it's late-bound (`ReFree` in this case, + // since it has been liberated), map it back to the early-bound lifetime of + // the GAT. Since RPITITs also have all of the fn's generics, we slice only + // the end of the list corresponding to the opaque's generics. + for param in &generics.params[tcx.generics_of(fn_def_id).params.len()..] { + let orig_lt = tcx.map_rpit_lifetime_to_fn_lifetime(param.def_id.expect_local()); + if matches!(*orig_lt, ty::ReFree(..)) { + mapping.insert( + orig_lt, + ty::Region::new_early_bound( + tcx, + ty::EarlyBoundRegion { + def_id: param.def_id, + index: param.index, + name: param.name, + }, + ), + ); + } + } + // FIXME: This could use a real folder, I guess. + let remapped_wf_tys = tcx.fold_regions( + tcx.assumed_wf_types(fn_def_id.expect_local()).to_vec(), + |region, _| { + // If `region` is a `ReFree` that is captured by the + // opaque, remap it to its corresponding the early- + // bound region. + if let Some(remapped_region) = mapping.get(®ion) { + *remapped_region + } else { + region + } + }, + ); + tcx.arena.alloc_from_iter(remapped_wf_tys) + } + // Assumed wf types for RPITITs in an impl just inherit (and instantiate) + // the assumed wf types of the trait's RPITIT GAT. + ty::ImplTraitInTraitData::Impl { .. } => { + let impl_def_id = tcx.local_parent(def_id); + let rpitit_def_id = tcx.associated_item(def_id).trait_item_def_id.unwrap(); + let args = ty::GenericArgs::identity_for_item(tcx, def_id).rebase_onto( + tcx, + impl_def_id.to_def_id(), + tcx.impl_trait_ref(impl_def_id).unwrap().instantiate_identity().args, + ); + tcx.arena.alloc_from_iter( + ty::EarlyBinder::bind(tcx.assumed_wf_types_for_rpitit(rpitit_def_id)) + .iter_instantiated_copied(tcx, args) + .chain(tcx.assumed_wf_types(impl_def_id).into_iter().copied()), + ) + } + }, DefKind::AssocConst | DefKind::AssocTy => tcx.assumed_wf_types(tcx.local_parent(def_id)), DefKind::OpaqueTy => match tcx.def_kind(tcx.local_parent(def_id)) { - DefKind::TyAlias => ty::List::empty(), + DefKind::TyAlias { .. } => ty::List::empty(), DefKind::AssocTy => tcx.assumed_wf_types(tcx.local_parent(def_id)), // Nested opaque types only occur in associated types: // ` type Opaque<T> = impl Trait<&'static T, AssocTy = impl Nested>; ` // assumed_wf_types should include those of `Opaque<T>`, `Opaque<T>` itself // and `&'static T`. DefKind::OpaqueTy => bug!("unimplemented implied bounds for nested opaque types"), - def_kind @ _ => { + def_kind => { bug!("unimplemented implied bounds for opaque types with parent {def_kind:?}") } }, @@ -61,7 +136,7 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<' | DefKind::Enum | DefKind::Variant | DefKind::Trait - | DefKind::TyAlias + | DefKind::TyAlias { .. } | DefKind::ForeignTy | DefKind::TraitAlias | DefKind::TyParam @@ -75,7 +150,6 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<' | DefKind::ForeignMod | DefKind::AnonConst | DefKind::InlineConst - | DefKind::ImplTraitPlaceholder | DefKind::Field | DefKind::LifetimeParam | DefKind::GlobalAsm |