diff options
Diffstat (limited to 'compiler/rustc_hir_analysis/src')
| -rw-r--r-- | compiler/rustc_hir_analysis/src/astconv/mod.rs | 33 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/check/check.rs | 91 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/check/wfcheck.rs | 29 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/collect/predicates_of.rs | 123 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/variance/mod.rs | 94 |
5 files changed, 225 insertions, 145 deletions
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs index 3f4891efaa7..e744ed2dcc5 100644 --- a/compiler/rustc_hir_analysis/src/astconv/mod.rs +++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs @@ -2777,35 +2777,11 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { let substs = InternalSubsts::for_item(tcx, def_id, |param, _| { if let Some(i) = (param.index as usize).checked_sub(generics.parent_count) { // Our own parameters are the resolved lifetimes. - if let GenericParamDefKind::Lifetime = param.kind { - if let hir::GenericArg::Lifetime(lifetime) = &lifetimes[i] { - self.ast_region_to_region(lifetime, None).into() - } else { - bug!() - } - } else { - bug!() - } + let GenericParamDefKind::Lifetime { .. } = param.kind else { bug!() }; + let hir::GenericArg::Lifetime(lifetime) = &lifetimes[i] else { bug!() }; + self.ast_region_to_region(lifetime, None).into() } else { - match param.kind { - // For RPIT (return position impl trait), only lifetimes - // mentioned in the impl Trait predicate are captured by - // the opaque type, so the lifetime parameters from the - // parent item need to be replaced with `'static`. - // - // For `impl Trait` in the types of statics, constants, - // locals and type aliases. These capture all parent - // lifetimes, so they can use their identity subst. - GenericParamDefKind::Lifetime - if matches!( - origin, - hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..) - ) => - { - tcx.lifetimes.re_static.into() - } - _ => tcx.mk_param_from_def(param), - } + tcx.mk_param_from_def(param) } }); debug!("impl_trait_ty_to_ty: substs={:?}", substs); @@ -2982,6 +2958,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { Some(tcx.liberate_late_bound_regions(fn_hir_id.expect_owner().to_def_id(), ty)) } + #[instrument(level = "trace", skip(self, generate_err))] fn validate_late_bound_regions( &self, constrained_regions: FxHashSet<ty::BoundRegionKind>, diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs index b4805de9618..33b9c61993a 100644 --- a/compiler/rustc_hir_analysis/src/check/check.rs +++ b/compiler/rustc_hir_analysis/src/check/check.rs @@ -10,6 +10,7 @@ use rustc_hir::def::{CtorKind, DefKind, Res}; use rustc_hir::def_id::{DefId, LocalDefId}; use rustc_hir::intravisit::Visitor; use rustc_hir::{ItemKind, Node, PathSegment}; +use rustc_infer::infer::opaque_types::ConstrainOpaqueTypeRegionVisitor; use rustc_infer::infer::outlives::env::OutlivesEnvironment; use rustc_infer::infer::{DefiningAnchor, RegionVariableOrigin, TyCtxtInferExt}; use rustc_infer::traits::Obligation; @@ -229,7 +230,9 @@ fn check_opaque<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) { let substs = InternalSubsts::identity_for_item(tcx, item.owner_id.to_def_id()); let span = tcx.def_span(item.owner_id.def_id); - check_opaque_for_inheriting_lifetimes(tcx, item.owner_id.def_id, span); + if !tcx.features().impl_trait_projections { + check_opaque_for_inheriting_lifetimes(tcx, item.owner_id.def_id, span); + } if tcx.type_of(item.owner_id.def_id).references_error() { return; } @@ -238,6 +241,7 @@ fn check_opaque<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) { } check_opaque_meets_bounds(tcx, item.owner_id.def_id, substs, span, &origin); } + /// Checks that an opaque type does not use `Self` or `T::Foo` projections that would result /// in "inheriting lifetimes". #[instrument(level = "debug", skip(tcx, span))] @@ -249,39 +253,11 @@ pub(super) fn check_opaque_for_inheriting_lifetimes<'tcx>( let item = tcx.hir().expect_item(def_id); debug!(?item, ?span); - struct FoundParentLifetime; - struct FindParentLifetimeVisitor<'tcx>(&'tcx ty::Generics); - impl<'tcx> ty::visit::TypeVisitor<'tcx> for FindParentLifetimeVisitor<'tcx> { - type BreakTy = FoundParentLifetime; - - fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> { - debug!("FindParentLifetimeVisitor: r={:?}", r); - if let ty::ReEarlyBound(ty::EarlyBoundRegion { index, .. }) = *r { - if index < self.0.parent_count as u32 { - return ControlFlow::Break(FoundParentLifetime); - } else { - return ControlFlow::CONTINUE; - } - } - - r.super_visit_with(self) - } - - fn visit_const(&mut self, c: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> { - if let ty::ConstKind::Unevaluated(..) = c.kind() { - // FIXME(#72219) We currently don't detect lifetimes within substs - // which would violate this check. Even though the particular substitution is not used - // within the const, this should still be fixed. - return ControlFlow::CONTINUE; - } - c.super_visit_with(self) - } - } - struct ProhibitOpaqueVisitor<'tcx> { tcx: TyCtxt<'tcx>, opaque_identity_ty: Ty<'tcx>, - generics: &'tcx ty::Generics, + parent_count: u32, + references_parent_regions: bool, selftys: Vec<(Span, Option<String>)>, } @@ -289,12 +265,25 @@ pub(super) fn check_opaque_for_inheriting_lifetimes<'tcx>( type BreakTy = Ty<'tcx>; fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { - debug!("check_opaque_for_inheriting_lifetimes: (visit_ty) t={:?}", t); + debug!(?t, "root_visit_ty"); if t == self.opaque_identity_ty { ControlFlow::CONTINUE } else { - t.super_visit_with(&mut FindParentLifetimeVisitor(self.generics)) - .map_break(|FoundParentLifetime| t) + t.visit_with(&mut ConstrainOpaqueTypeRegionVisitor { + tcx: self.tcx, + op: |region| { + if let ty::ReEarlyBound(ty::EarlyBoundRegion { index, .. }) = *region + && index < self.parent_count + { + self.references_parent_regions= true; + } + }, + }); + if self.references_parent_regions { + ControlFlow::Break(t) + } else { + ControlFlow::CONTINUE + } } } } @@ -327,15 +316,20 @@ pub(super) fn check_opaque_for_inheriting_lifetimes<'tcx>( if let ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..), + in_trait, .. }) = item.kind { + let substs = InternalSubsts::identity_for_item(tcx, def_id.to_def_id()); + let opaque_identity_ty = if in_trait { + tcx.mk_projection(def_id.to_def_id(), substs) + } else { + tcx.mk_opaque(def_id.to_def_id(), substs) + }; let mut visitor = ProhibitOpaqueVisitor { - opaque_identity_ty: tcx.mk_opaque( - def_id.to_def_id(), - InternalSubsts::identity_for_item(tcx, def_id.to_def_id()), - ), - generics: tcx.generics_of(def_id), + opaque_identity_ty, + parent_count: tcx.generics_of(def_id).parent_count as u32, + references_parent_regions: false, tcx, selftys: vec![], }; @@ -343,10 +337,6 @@ pub(super) fn check_opaque_for_inheriting_lifetimes<'tcx>( .explicit_item_bounds(def_id) .iter() .try_for_each(|(predicate, _)| predicate.visit_with(&mut visitor)); - debug!( - "check_opaque_for_inheriting_lifetimes: prohibit_opaque={:?}, visitor.opaque_identity_ty={:?}, visitor.generics={:?}", - prohibit_opaque, visitor.opaque_identity_ty, visitor.generics - ); if let Some(ty) = prohibit_opaque.break_value() { visitor.visit_item(&item); @@ -357,15 +347,16 @@ pub(super) fn check_opaque_for_inheriting_lifetimes<'tcx>( _ => unreachable!(), }; - let mut err = struct_span_err!( - tcx.sess, + let mut err = feature_err( + &tcx.sess.parse_sess, + sym::impl_trait_projections, span, - E0760, - "`{}` return type cannot contain a projection or `Self` that references lifetimes from \ - a parent scope", - if is_async { "async fn" } else { "impl Trait" }, + &format!( + "`{}` return type cannot contain a projection or `Self` that references \ + lifetimes from a parent scope", + if is_async { "async fn" } else { "impl Trait" }, + ), ); - for (span, name) in visitor.selftys { err.span_suggestion( span, diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs index 1d7ceda725a..b81f9d7a6d2 100644 --- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs +++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs @@ -1539,7 +1539,6 @@ fn check_fn_or_method<'tcx>( check_return_position_impl_trait_in_trait_bounds( tcx, - wfcx, def_id, sig.output(), hir_decl.output.span(), @@ -1575,9 +1574,9 @@ fn check_fn_or_method<'tcx>( /// Basically `check_associated_type_bounds`, but separated for now and should be /// deduplicated when RPITITs get lowered into real associated items. +#[tracing::instrument(level = "trace", skip(tcx))] fn check_return_position_impl_trait_in_trait_bounds<'tcx>( tcx: TyCtxt<'tcx>, - wfcx: &WfCheckingCtxt<'_, 'tcx>, fn_def_id: LocalDefId, fn_output: Ty<'tcx>, span: Span, @@ -1591,18 +1590,22 @@ fn check_return_position_impl_trait_in_trait_bounds<'tcx>( && tcx.def_kind(proj.item_def_id) == DefKind::ImplTraitPlaceholder && tcx.impl_trait_in_trait_parent(proj.item_def_id) == fn_def_id.to_def_id() { - let bounds = wfcx.tcx().explicit_item_bounds(proj.item_def_id); - let wf_obligations = bounds.iter().flat_map(|&(bound, bound_span)| { - let normalized_bound = wfcx.normalize(span, None, bound); - traits::wf::predicate_obligations( - wfcx.infcx, - wfcx.param_env, - wfcx.body_id, - normalized_bound, - bound_span, - ) + // Create a new context, since we want the opaque's ParamEnv and not the parent's. + let span = tcx.def_span(proj.item_def_id); + enter_wf_checking_ctxt(tcx, span, proj.item_def_id.expect_local(), |wfcx| { + let bounds = wfcx.tcx().explicit_item_bounds(proj.item_def_id); + let wf_obligations = bounds.iter().flat_map(|&(bound, bound_span)| { + let normalized_bound = wfcx.normalize(span, None, bound); + traits::wf::predicate_obligations( + wfcx.infcx, + wfcx.param_env, + wfcx.body_id, + normalized_bound, + bound_span, + ) + }); + wfcx.register_obligations(wf_obligations); }); - wfcx.register_obligations(wf_obligations); } } } diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs index e2da580de0c..c3f1bb457f7 100644 --- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs +++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs @@ -84,60 +84,30 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP Node::ImplItem(item) => item.generics, - Node::Item(item) => { - match item.kind { - ItemKind::Impl(ref impl_) => { - if impl_.defaultness.is_default() { - is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy); - } - &impl_.generics + Node::Item(item) => match item.kind { + ItemKind::Impl(ref impl_) => { + if impl_.defaultness.is_default() { + is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy); } - ItemKind::Fn(.., ref generics, _) - | ItemKind::TyAlias(_, ref generics) - | ItemKind::Enum(_, ref generics) - | ItemKind::Struct(_, ref generics) - | ItemKind::Union(_, ref generics) => *generics, - - ItemKind::Trait(_, _, ref generics, ..) => { - is_trait = Some(ty::TraitRef::identity(tcx, def_id)); - *generics - } - ItemKind::TraitAlias(ref generics, _) => { - is_trait = Some(ty::TraitRef::identity(tcx, def_id)); - *generics - } - ItemKind::OpaqueTy(OpaqueTy { - origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..), - .. - }) => { - // return-position impl trait - // - // We don't inherit predicates from the parent here: - // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}` - // then the return type is `f::<'static, T>::{{opaque}}`. - // - // If we inherited the predicates of `f` then we would - // require that `T: 'static` to show that the return - // type is well-formed. - // - // The only way to have something with this opaque type - // is from the return type of the containing function, - // which will ensure that the function's predicates - // hold. - return ty::GenericPredicates { parent: None, predicates: &[] }; - } - ItemKind::OpaqueTy(OpaqueTy { - ref generics, - origin: hir::OpaqueTyOrigin::TyAlias, - .. - }) => { - // type-alias impl trait - generics - } - - _ => NO_GENERICS, + &impl_.generics } - } + ItemKind::Fn(.., ref generics, _) + | ItemKind::TyAlias(_, ref generics) + | ItemKind::Enum(_, ref generics) + | ItemKind::Struct(_, ref generics) + | ItemKind::Union(_, ref generics) => *generics, + + ItemKind::Trait(_, _, ref generics, ..) => { + is_trait = Some(ty::TraitRef::identity(tcx, def_id)); + *generics + } + ItemKind::TraitAlias(ref generics, _) => { + is_trait = Some(ty::TraitRef::identity(tcx, def_id)); + *generics + } + ItemKind::OpaqueTy(OpaqueTy { ref generics, .. }) => generics, + _ => NO_GENERICS, + }, Node::ForeignItem(item) => match item.kind { ForeignItemKind::Static(..) => NO_GENERICS, @@ -181,6 +151,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP trace!(?predicates); trace!(?ast_generics); + trace!(?generics); // Collect the predicates that were written inline by the user on each // type parameter (e.g., `<T: Foo>`). @@ -299,6 +270,54 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP ); } + // Opaque types duplicate some of their generic parameters. + // We create bi-directional Outlives predicates between the original + // and the duplicated parameter, to ensure that they do not get out of sync. + if let Node::Item(&Item { kind: ItemKind::OpaqueTy(..), .. }) = node { + let opaque_ty_id = tcx.hir().get_parent_node(hir_id); + let opaque_ty_node = tcx.hir().get(opaque_ty_id); + let Node::Ty(&Ty { kind: TyKind::OpaqueDef(_, lifetimes, _), .. }) = opaque_ty_node else { + bug!("unexpected {opaque_ty_node:?}") + }; + debug!(?lifetimes); + for (arg, duplicate) in std::iter::zip(lifetimes, ast_generics.params) { + let hir::GenericArg::Lifetime(arg) = arg else { bug!() }; + let orig_region = <dyn AstConv<'_>>::ast_region_to_region(&icx, &arg, None); + if !matches!(orig_region.kind(), ty::ReEarlyBound(..)) { + // Only early-bound regions can point to the original generic parameter. + continue; + } + + let hir::GenericParamKind::Lifetime { .. } = duplicate.kind else { continue }; + let dup_def = tcx.hir().local_def_id(duplicate.hir_id).to_def_id(); + + let Some(dup_index) = generics.param_def_id_to_index(tcx, dup_def) else { bug!() }; + + let dup_region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion { + def_id: dup_def, + index: dup_index, + name: duplicate.name.ident().name, + })); + predicates.push(( + ty::Binder::dummy(ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate( + orig_region, + dup_region, + ))) + .to_predicate(icx.tcx), + duplicate.span, + )); + predicates.push(( + ty::Binder::dummy(ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate( + dup_region, + orig_region, + ))) + .to_predicate(icx.tcx), + duplicate.span, + )); + } + debug!(?predicates); + } + ty::GenericPredicates { parent: generics.parent, predicates: tcx.arena.alloc_from_iter(predicates), diff --git a/compiler/rustc_hir_analysis/src/variance/mod.rs b/compiler/rustc_hir_analysis/src/variance/mod.rs index 82103c5a03b..b6137f89cad 100644 --- a/compiler/rustc_hir_analysis/src/variance/mod.rs +++ b/compiler/rustc_hir_analysis/src/variance/mod.rs @@ -5,9 +5,10 @@ use rustc_arena::DroplessArena; use rustc_hir::def::DefKind; -use rustc_hir::def_id::DefId; +use rustc_hir::def_id::{DefId, LocalDefId}; use rustc_middle::ty::query::Providers; -use rustc_middle::ty::{self, CrateVariancesMap, TyCtxt}; +use rustc_middle::ty::{self, CrateVariancesMap, TyCtxt, TypeSuperVisitable, TypeVisitable}; +use std::ops::ControlFlow; /// Defines the `TermsContext` basically houses an arena where we can /// allocate terms. @@ -50,6 +51,9 @@ fn variances_of(tcx: TyCtxt<'_>, item_def_id: DefId) -> &[ty::Variance] { | DefKind::Union | DefKind::Variant | DefKind::Ctor(..) => {} + DefKind::OpaqueTy | DefKind::ImplTraitPlaceholder => { + return variance_of_opaque(tcx, item_def_id.expect_local()); + } _ => { // Variance not relevant. span_bug!(tcx.def_span(item_def_id), "asked to compute variance for wrong kind of item") @@ -61,3 +65,89 @@ fn variances_of(tcx: TyCtxt<'_>, item_def_id: DefId) -> &[ty::Variance] { let crate_map = tcx.crate_variances(()); crate_map.variances.get(&item_def_id).copied().unwrap_or(&[]) } + +#[instrument(level = "trace", skip(tcx), ret)] +fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Variance] { + let generics = tcx.generics_of(item_def_id); + + // Opaque types may only use regions that are bound. So for + // ```rust + // type Foo<'a, 'b, 'c> = impl Trait<'a> + 'b; + // ``` + // we may not use `'c` in the hidden type. + struct OpaqueTypeLifetimeCollector { + variances: Vec<ty::Variance>, + } + + impl<'tcx> ty::TypeVisitor<'tcx> for OpaqueTypeLifetimeCollector { + #[instrument(level = "trace", skip(self), ret)] + fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> { + if let ty::RegionKind::ReEarlyBound(ebr) = r.kind() { + self.variances[ebr.index as usize] = ty::Invariant; + } + r.super_visit_with(self) + } + } + + // By default, RPIT are invariant wrt type and const generics, but they are bivariant wrt + // lifetime generics. + let mut variances: Vec<_> = std::iter::repeat(ty::Invariant).take(generics.count()).collect(); + + // Mark all lifetimes from parent generics as unused (Bivariant). + // This will be overridden later if required. + { + let mut generics = generics; + while let Some(def_id) = generics.parent { + generics = tcx.generics_of(def_id); + for param in &generics.params { + match param.kind { + ty::GenericParamDefKind::Lifetime => { + variances[param.index as usize] = ty::Bivariant; + } + ty::GenericParamDefKind::Type { .. } + | ty::GenericParamDefKind::Const { .. } => {} + } + } + } + } + + let mut collector = OpaqueTypeLifetimeCollector { variances }; + let id_substs = ty::InternalSubsts::identity_for_item(tcx, item_def_id.to_def_id()); + for pred in tcx.bound_explicit_item_bounds(item_def_id.to_def_id()).transpose_iter() { + let pred = pred.map_bound(|(pred, _)| *pred).subst(tcx, id_substs); + debug!(?pred); + + // We only ignore opaque type substs if the opaque type is the outermost type. + // The opaque type may be nested within itself via recursion in e.g. + // type Foo<'a> = impl PartialEq<Foo<'a>>; + // which thus mentions `'a` and should thus accept hidden types that borrow 'a + // instead of requiring an additional `+ 'a`. + match pred.kind().skip_binder() { + ty::PredicateKind::Trait(ty::TraitPredicate { + trait_ref: ty::TraitRef { def_id: _, substs }, + constness: _, + polarity: _, + }) => { + for subst in &substs[1..] { + subst.visit_with(&mut collector); + } + } + ty::PredicateKind::Projection(ty::ProjectionPredicate { + projection_ty: ty::ProjectionTy { substs, item_def_id: _ }, + term, + }) => { + for subst in &substs[1..] { + subst.visit_with(&mut collector); + } + term.visit_with(&mut collector); + } + ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_, region)) => { + region.visit_with(&mut collector); + } + _ => { + pred.visit_with(&mut collector); + } + } + } + tcx.arena.alloc_from_iter(collector.variances.into_iter()) +} |