diff options
| -rw-r--r-- | compiler/rustc_hir_analysis/src/check/compare_impl_item.rs | 180 | ||||
| -rw-r--r-- | tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs | 11 |
2 files changed, 114 insertions, 77 deletions
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs index f7664b0c3a1..90babbb63a0 100644 --- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs +++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs @@ -2162,7 +2162,7 @@ pub(super) fn check_type_bounds<'tcx>( impl_ty: ty::AssocItem, impl_trait_ref: ty::TraitRef<'tcx>, ) -> Result<(), ErrorGuaranteed> { - let param_env = param_env_with_gat_bounds(tcx, trait_ty, impl_ty, impl_trait_ref); + let param_env = param_env_with_gat_bounds(tcx, impl_ty, impl_trait_ref); debug!(?param_env); let container_id = impl_ty.container_id(tcx); @@ -2288,7 +2288,6 @@ pub(super) fn check_type_bounds<'tcx>( /// the trait (notably, that `X: Eq` and `T: Family`). fn param_env_with_gat_bounds<'tcx>( tcx: TyCtxt<'tcx>, - trait_ty: ty::AssocItem, impl_ty: ty::AssocItem, impl_trait_ref: ty::TraitRef<'tcx>, ) -> ty::ParamEnv<'tcx> { @@ -2296,84 +2295,111 @@ fn param_env_with_gat_bounds<'tcx>( let container_id = impl_ty.container_id(tcx); let mut predicates = param_env.caller_bounds().to_vec(); - let mut bound_vars: smallvec::SmallVec<[ty::BoundVariableKind; 8]> = - smallvec::SmallVec::with_capacity(tcx.generics_of(impl_ty.def_id).params.len()); - // Extend the impl's identity args with late-bound GAT vars - let normalize_impl_ty_args = ty::GenericArgs::identity_for_item(tcx, container_id).extend_to( - tcx, - impl_ty.def_id, - |param, _| match param.kind { - GenericParamDefKind::Type { .. } => { - let kind = ty::BoundTyKind::Param(param.def_id, param.name); - let bound_var = ty::BoundVariableKind::Ty(kind); - bound_vars.push(bound_var); - Ty::new_bound( - tcx, - ty::INNERMOST, - ty::BoundTy { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, - ) - .into() + // for RPITITs, we should install predicates that allow us to project all + // of the RPITITs associated with the same body. This is because checking + // the item bounds of RPITITs often involves nested RPITITs having to prove + // bounds about themselves. + let impl_tys_to_install = match impl_ty.opt_rpitit_info { + None => vec![impl_ty], + Some( + ty::ImplTraitInTraitData::Impl { fn_def_id } + | ty::ImplTraitInTraitData::Trait { fn_def_id, .. }, + ) => tcx + .associated_types_for_impl_traits_in_associated_fn(fn_def_id) + .iter() + .map(|def_id| tcx.associated_item(*def_id)) + .collect(), + }; + + for impl_ty in impl_tys_to_install { + let trait_ty = match impl_ty.container { + ty::AssocItemContainer::TraitContainer => impl_ty, + ty::AssocItemContainer::ImplContainer => { + tcx.associated_item(impl_ty.trait_item_def_id.unwrap()) } - GenericParamDefKind::Lifetime => { - let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name); - let bound_var = ty::BoundVariableKind::Region(kind); - bound_vars.push(bound_var); - ty::Region::new_late_bound( - tcx, - ty::INNERMOST, - ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, - ) - .into() + }; + + let mut bound_vars: smallvec::SmallVec<[ty::BoundVariableKind; 8]> = + smallvec::SmallVec::with_capacity(tcx.generics_of(impl_ty.def_id).params.len()); + // Extend the impl's identity args with late-bound GAT vars + let normalize_impl_ty_args = ty::GenericArgs::identity_for_item(tcx, container_id) + .extend_to(tcx, impl_ty.def_id, |param, _| match param.kind { + GenericParamDefKind::Type { .. } => { + let kind = ty::BoundTyKind::Param(param.def_id, param.name); + let bound_var = ty::BoundVariableKind::Ty(kind); + bound_vars.push(bound_var); + Ty::new_bound( + tcx, + ty::INNERMOST, + ty::BoundTy { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, + ) + .into() + } + GenericParamDefKind::Lifetime => { + let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name); + let bound_var = ty::BoundVariableKind::Region(kind); + bound_vars.push(bound_var); + ty::Region::new_late_bound( + tcx, + ty::INNERMOST, + ty::BoundRegion { + var: ty::BoundVar::from_usize(bound_vars.len() - 1), + kind, + }, + ) + .into() + } + GenericParamDefKind::Const { .. } => { + let bound_var = ty::BoundVariableKind::Const; + bound_vars.push(bound_var); + ty::Const::new_bound( + tcx, + ty::INNERMOST, + ty::BoundVar::from_usize(bound_vars.len() - 1), + tcx.type_of(param.def_id) + .no_bound_vars() + .expect("const parameter types cannot be generic"), + ) + .into() + } + }); + // When checking something like + // + // trait X { type Y: PartialEq<<Self as X>::Y> } + // impl X for T { default type Y = S; } + // + // We will have to prove the bound S: PartialEq<<T as X>::Y>. In this case + // we want <T as X>::Y to normalize to S. This is valid because we are + // checking the default value specifically here. Add this equality to the + // ParamEnv for normalization specifically. + let normalize_impl_ty = + tcx.type_of(impl_ty.def_id).instantiate(tcx, normalize_impl_ty_args); + let rebased_args = + normalize_impl_ty_args.rebase_onto(tcx, container_id, impl_trait_ref.args); + let bound_vars = tcx.mk_bound_variable_kinds(&bound_vars); + + match normalize_impl_ty.kind() { + ty::Alias(ty::Projection, proj) + if proj.def_id == trait_ty.def_id && proj.args == rebased_args => + { + // Don't include this predicate if the projected type is + // exactly the same as the projection. This can occur in + // (somewhat dubious) code like this: + // + // impl<T> X for T where T: X { type Y = <T as X>::Y; } } - GenericParamDefKind::Const { .. } => { - let bound_var = ty::BoundVariableKind::Const; - bound_vars.push(bound_var); - ty::Const::new_bound( - tcx, - ty::INNERMOST, - ty::BoundVar::from_usize(bound_vars.len() - 1), - tcx.type_of(param.def_id) - .no_bound_vars() - .expect("const parameter types cannot be generic"), + _ => predicates.push( + ty::Binder::bind_with_vars( + ty::ProjectionPredicate { + projection_ty: ty::AliasTy::new(tcx, trait_ty.def_id, rebased_args), + term: normalize_impl_ty.into(), + }, + bound_vars, ) - .into() - } - }, - ); - // When checking something like - // - // trait X { type Y: PartialEq<<Self as X>::Y> } - // impl X for T { default type Y = S; } - // - // We will have to prove the bound S: PartialEq<<T as X>::Y>. In this case - // we want <T as X>::Y to normalize to S. This is valid because we are - // checking the default value specifically here. Add this equality to the - // ParamEnv for normalization specifically. - let normalize_impl_ty = tcx.type_of(impl_ty.def_id).instantiate(tcx, normalize_impl_ty_args); - let rebased_args = normalize_impl_ty_args.rebase_onto(tcx, container_id, impl_trait_ref.args); - let bound_vars = tcx.mk_bound_variable_kinds(&bound_vars); - - match normalize_impl_ty.kind() { - ty::Alias(ty::Projection, proj) - if proj.def_id == trait_ty.def_id && proj.args == rebased_args => - { - // Don't include this predicate if the projected type is - // exactly the same as the projection. This can occur in - // (somewhat dubious) code like this: - // - // impl<T> X for T where T: X { type Y = <T as X>::Y; } - } - _ => predicates.push( - ty::Binder::bind_with_vars( - ty::ProjectionPredicate { - projection_ty: ty::AliasTy::new(tcx, trait_ty.def_id, rebased_args), - term: normalize_impl_ty.into(), - }, - bound_vars, - ) - .to_predicate(tcx), - ), - }; + .to_predicate(tcx), + ), + }; + } ty::ParamEnv::new(tcx.mk_clauses(&predicates), Reveal::UserFacing) } diff --git a/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs b/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs new file mode 100644 index 00000000000..b97fd7d1ffe --- /dev/null +++ b/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs @@ -0,0 +1,11 @@ +// check-pass + +use std::ops::Deref; + +trait Foo { + fn foo() -> impl Deref<Target = impl Deref<Target = impl Sized>> { + &&() + } +} + +fn main() {} |