From 44c10e4cb0835f34b2ac85188f0ad44fab14446b Mon Sep 17 00:00:00 2001 From: Camille GILLOT Date: Tue, 25 Oct 2022 15:08:20 +0000 Subject: [PATCH] Resolve lifetimes independently for each item-like. --- .../src/collect/lifetimes.rs | 243 +++++------------- compiler/rustc_middle/src/query/mod.rs | 11 +- 2 files changed, 67 insertions(+), 187 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/collect/lifetimes.rs b/compiler/rustc_hir_analysis/src/collect/lifetimes.rs index c64177eea3f..1fec8f027bd 100644 --- a/compiler/rustc_hir_analysis/src/collect/lifetimes.rs +++ b/compiler/rustc_hir_analysis/src/collect/lifetimes.rs @@ -94,11 +94,6 @@ struct LifetimeContext<'a, 'tcx> { tcx: TyCtxt<'tcx>, map: &'a mut NamedRegionMap, scope: ScopeRef<'a>, - - /// Indicates that we only care about the definition of a trait. This should - /// be false if the `Item` we are resolving lifetimes for is not a trait or - /// we eventually need lifetimes resolve for trait items. - trait_definition_only: bool, } #[derive(Debug)] @@ -166,7 +161,9 @@ enum Scope<'a> { s: ScopeRef<'a>, }, - Root, + Root { + opt_parent_item: Option, + }, } #[derive(Copy, Clone, Debug)] @@ -214,95 +211,58 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { .field("s", &"..") .finish(), Scope::TraitRefBoundary { s: _ } => f.debug_struct("TraitRefBoundary").finish(), - Scope::Root => f.debug_struct("Root").finish(), + Scope::Root { opt_parent_item } => { + f.debug_struct("Root").field("opt_parent_item", &opt_parent_item).finish() + } } } } type ScopeRef<'a> = &'a Scope<'a>; -const ROOT_SCOPE: ScopeRef<'static> = &Scope::Root; - pub(crate) fn provide(providers: &mut ty::query::Providers) { *providers = ty::query::Providers { - resolve_lifetimes_trait_definition, resolve_lifetimes, - named_region_map: |tcx, id| resolve_lifetimes_for(tcx, id).defs.get(&id), + named_region_map: |tcx, id| tcx.resolve_lifetimes(id).defs.get(&id), is_late_bound_map, object_lifetime_default, - late_bound_vars_map: |tcx, id| resolve_lifetimes_for(tcx, id).late_bound_vars.get(&id), + late_bound_vars_map: |tcx, id| tcx.resolve_lifetimes(id).late_bound_vars.get(&id), ..*providers }; } -/// Like `resolve_lifetimes`, but does not resolve lifetimes for trait items. -/// Also does not generate any diagnostics. -/// -/// This is ultimately a subset of the `resolve_lifetimes` work. It effectively -/// resolves lifetimes only within the trait "header" -- that is, the trait -/// and supertrait list. In contrast, `resolve_lifetimes` resolves all the -/// lifetimes within the trait and its items. There is room to refactor this, -/// for example to resolve lifetimes for each trait item in separate queries, -/// but it's convenient to do the entire trait at once because the lifetimes -/// from the trait definition are in scope within the trait items as well. -/// -/// The reason for this separate call is to resolve what would otherwise -/// be a cycle. Consider this example: -/// -/// ```ignore UNSOLVED (maybe @jackh726 knows what lifetime parameter to give Sub) -/// trait Base<'a> { -/// type BaseItem; -/// } -/// trait Sub<'b>: for<'a> Base<'a> { -/// type SubItem: Sub; -/// } -/// ``` -/// -/// When we resolve `Sub` and all its items, we also have to resolve `Sub`. -/// To figure out the index of `'b`, we have to know about the supertraits -/// of `Sub` so that we can determine that the `for<'a>` will be in scope. -/// (This is because we -- currently at least -- flatten all the late-bound -/// lifetimes into a single binder.) This requires us to resolve the -/// *trait definition* of `Sub`; basically just enough lifetime information -/// to look at the supertraits. -#[instrument(level = "debug", skip(tcx))] -fn resolve_lifetimes_trait_definition( - tcx: TyCtxt<'_>, - local_def_id: LocalDefId, -) -> ResolveLifetimes { - convert_named_region_map(do_resolve(tcx, local_def_id, true)) -} - /// Computes the `ResolveLifetimes` map that contains data for an entire `Item`. /// You should not read the result of this query directly, but rather use /// `named_region_map`, `is_late_bound_map`, etc. #[instrument(level = "debug", skip(tcx))] -fn resolve_lifetimes(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> ResolveLifetimes { - convert_named_region_map(do_resolve(tcx, local_def_id, false)) -} - -fn do_resolve( - tcx: TyCtxt<'_>, - local_def_id: LocalDefId, - trait_definition_only: bool, -) -> NamedRegionMap { - let item = tcx.hir().expect_item(local_def_id); +fn resolve_lifetimes(tcx: TyCtxt<'_>, local_def_id: hir::OwnerId) -> ResolveLifetimes { let mut named_region_map = NamedRegionMap { defs: Default::default(), late_bound_vars: Default::default() }; let mut visitor = LifetimeContext { tcx, map: &mut named_region_map, - scope: ROOT_SCOPE, - trait_definition_only, + scope: &Scope::Root { opt_parent_item: None }, }; - visitor.visit_item(item); - - named_region_map -} + match tcx.hir().owner(local_def_id) { + hir::OwnerNode::Item(item) => visitor.visit_item(item), + hir::OwnerNode::ForeignItem(item) => visitor.visit_foreign_item(item), + hir::OwnerNode::TraitItem(item) => { + let scope = + Scope::Root { opt_parent_item: Some(tcx.local_parent(item.owner_id.def_id)) }; + visitor.scope = &scope; + visitor.visit_trait_item(item) + } + hir::OwnerNode::ImplItem(item) => { + let scope = + Scope::Root { opt_parent_item: Some(tcx.local_parent(item.owner_id.def_id)) }; + visitor.scope = &scope; + visitor.visit_impl_item(item) + } + hir::OwnerNode::Crate(_) => {} + } -fn convert_named_region_map(named_region_map: NamedRegionMap) -> ResolveLifetimes { let mut rl = ResolveLifetimes::default(); for (hir_id, v) in named_region_map.defs { @@ -319,53 +279,6 @@ fn convert_named_region_map(named_region_map: NamedRegionMap) -> ResolveLifetime rl } -/// Given `any` owner (structs, traits, trait methods, etc.), does lifetime resolution. -/// There are two important things this does. -/// First, we have to resolve lifetimes for -/// the entire *`Item`* that contains this owner, because that's the largest "scope" -/// where we can have relevant lifetimes. -/// Second, if we are asking for lifetimes in a trait *definition*, we use `resolve_lifetimes_trait_definition` -/// instead of `resolve_lifetimes`, which does not descend into the trait items and does not emit diagnostics. -/// This allows us to avoid cycles. Importantly, if we ask for lifetimes for lifetimes that have an owner -/// other than the trait itself (like the trait methods or associated types), then we just use the regular -/// `resolve_lifetimes`. -fn resolve_lifetimes_for<'tcx>(tcx: TyCtxt<'tcx>, def_id: hir::OwnerId) -> &'tcx ResolveLifetimes { - let item_id = item_for(tcx, def_id.def_id); - let local_def_id = item_id.owner_id.def_id; - if item_id.owner_id == def_id { - let item = tcx.hir().item(item_id); - match item.kind { - hir::ItemKind::Trait(..) => tcx.resolve_lifetimes_trait_definition(local_def_id), - _ => tcx.resolve_lifetimes(local_def_id), - } - } else { - tcx.resolve_lifetimes(local_def_id) - } -} - -/// Finds the `Item` that contains the given `LocalDefId` -fn item_for(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> hir::ItemId { - match tcx.hir().find_by_def_id(local_def_id) { - Some(Node::Item(item)) => { - return item.item_id(); - } - _ => {} - } - let item = { - let hir_id = tcx.hir().local_def_id_to_hir_id(local_def_id); - let mut parent_iter = tcx.hir().parent_iter(hir_id); - loop { - let node = parent_iter.next().map(|n| n.1); - match node { - Some(hir::Node::Item(item)) => break item.item_id(), - Some(hir::Node::Crate(_)) | None => bug!("Called `item_for` on an Item."), - _ => {} - } - } - }; - item -} - fn late_region_as_bound_region<'tcx>(tcx: TyCtxt<'tcx>, region: &Region) -> ty::BoundVariableKind { match region { Region::LateBound(_, _, def_id) => { @@ -383,7 +296,7 @@ fn poly_trait_ref_binder_info(&mut self) -> (Vec, BinderS let mut supertrait_lifetimes = vec![]; loop { match scope { - Scope::Body { .. } | Scope::Root => { + Scope::Body { .. } | Scope::Root { .. } => { break (vec![], BinderScopeType::Normal); } @@ -414,21 +327,12 @@ fn poly_trait_ref_binder_info(&mut self) -> (Vec, BinderS } } impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { - type NestedFilter = nested_filter::All; + type NestedFilter = nested_filter::OnlyBodies; fn nested_visit_map(&mut self) -> Self::Map { self.tcx.hir() } - // We want to nest trait/impl items in their parent, but nothing else. - fn visit_nested_item(&mut self, _: hir::ItemId) {} - - fn visit_trait_item_ref(&mut self, ii: &'tcx hir::TraitItemRef) { - if !self.trait_definition_only { - intravisit::walk_trait_item_ref(self, ii) - } - } - fn visit_nested_body(&mut self, body: hir::BodyId) { let body = self.tcx.hir().body(body); self.with(Scope::Body { id: body.id(), s: self.scope }, |this| { @@ -557,33 +461,21 @@ fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) { // their owner, we can keep going until we find the Item that owns that. We then // conservatively add all resolved lifetimes. Otherwise we run into problems in // cases like `type Foo<'a> = impl Bar`. - for (_hir_id, node) in self.tcx.hir().parent_iter(item.owner_id.into()) { - match node { - hir::Node::Item(parent_item) => { - let resolved_lifetimes: &ResolveLifetimes = self.tcx.resolve_lifetimes( - item_for(self.tcx, parent_item.owner_id.def_id).owner_id.def_id, - ); - // We need to add *all* deps, since opaque tys may want them from *us* - for (&owner, defs) in resolved_lifetimes.defs.iter() { - defs.iter().for_each(|(&local_id, region)| { - self.map.defs.insert(hir::HirId { owner, local_id }, *region); - }); - } - for (&owner, late_bound_vars) in - resolved_lifetimes.late_bound_vars.iter() - { - late_bound_vars.iter().for_each(|(&local_id, late_bound_vars)| { - self.record_late_bound_vars( - hir::HirId { owner, local_id }, - late_bound_vars.clone(), - ); - }); - } - break; - } - hir::Node::Crate(_) => bug!("No Item about an OpaqueTy"), - _ => {} - } + let parent_item = self.tcx.hir().get_parent_item(item.hir_id()); + let resolved_lifetimes: &ResolveLifetimes = self.tcx.resolve_lifetimes(parent_item); + // We need to add *all* deps, since opaque tys may want them from *us* + for (&owner, defs) in resolved_lifetimes.defs.iter() { + defs.iter().for_each(|(&local_id, region)| { + self.map.defs.insert(hir::HirId { owner, local_id }, *region); + }); + } + for (&owner, late_bound_vars) in resolved_lifetimes.late_bound_vars.iter() { + late_bound_vars.iter().for_each(|(&local_id, late_bound_vars)| { + self.record_late_bound_vars( + hir::HirId { owner, local_id }, + late_bound_vars.clone(), + ); + }); } } hir::ItemKind::TyAlias(_, ref generics) @@ -609,7 +501,7 @@ fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) { hir_id: item.hir_id(), lifetimes, scope_type: BinderScopeType::Normal, - s: ROOT_SCOPE, + s: self.scope, where_bound_origin: None, }; self.with(scope, |this| { @@ -766,30 +658,26 @@ fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) { // Ensure that the parent of the def is an item, not HRTB let parent_id = self.tcx.hir().get_parent_node(hir_id); if !parent_id.is_owner() { - if !self.trait_definition_only { - struct_span_err!( - self.tcx.sess, - lifetime.span, - E0657, - "`impl Trait` can only capture lifetimes \ + struct_span_err!( + self.tcx.sess, + lifetime.span, + E0657, + "`impl Trait` can only capture lifetimes \ bound at the fn or impl level" - ) - .emit(); - } + ) + .emit(); self.uninsert_lifetime_on_error(lifetime, def.unwrap()); } if let hir::Node::Item(hir::Item { kind: hir::ItemKind::OpaqueTy { .. }, .. }) = self.tcx.hir().get(parent_id) { - if !self.trait_definition_only { - let mut err = self.tcx.sess.struct_span_err( + let mut err = self.tcx.sess.struct_span_err( lifetime.span, "higher kinded lifetime bounds on nested opaque types are not supported yet", ); - err.span_note(self.tcx.def_span(def_id), "lifetime declared here"); - err.emit(); - } + err.span_note(self.tcx.def_span(def_id), "lifetime declared here"); + err.emit(); self.uninsert_lifetime_on_error(lifetime, def.unwrap()); } } @@ -1193,12 +1081,7 @@ fn with(&mut self, wrap_scope: Scope<'_>, f: F) F: for<'b> FnOnce(&mut LifetimeContext<'b, 'tcx>), { let LifetimeContext { tcx, map, .. } = self; - let mut this = LifetimeContext { - tcx: *tcx, - map, - scope: &wrap_scope, - trait_definition_only: self.trait_definition_only, - }; + let mut this = LifetimeContext { tcx: *tcx, map, scope: &wrap_scope }; let span = debug_span!("scope", scope = ?TruncatedScopeDebug(&this.scope)); { let _enter = span.enter(); @@ -1303,7 +1186,13 @@ fn resolve_lifetime_ref( scope = s; } - Scope::Root => { + Scope::Root { opt_parent_item } => { + if let Some(parent_item) = opt_parent_item + && let parent_generics = self.tcx.generics_of(parent_item) + && parent_generics.param_def_id_to_index.contains_key(®ion_def_id.to_def_id()) + { + break Some(Region::EarlyBound(region_def_id.to_def_id())); + } break None; } @@ -1417,7 +1306,7 @@ fn resolve_lifetime_ref( err.emit(); return; } - Scope::Root => break, + Scope::Root { .. } => break, Scope::Binder { s, .. } | Scope::Body { s, .. } | Scope::Elision { s, .. } @@ -1495,7 +1384,7 @@ fn visit_segment_args( let mut scope = self.scope; loop { match *scope { - Scope::Root => break false, + Scope::Root { .. } => break false, Scope::Body { .. } => break true, @@ -1732,7 +1621,7 @@ fn resolve_object_lifetime_default(&mut self, lifetime_ref: &'tcx hir::Lifetime) scope = s; } - Scope::Root | Scope::Elision { .. } => break Region::Static, + Scope::Root { .. } | Scope::Elision { .. } => break Region::Static, Scope::Body { .. } | Scope::ObjectLifetimeDefault { lifetime: None, .. } => return, diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs index 00242e7eed7..1564cf414bd 100644 --- a/compiler/rustc_middle/src/query/mod.rs +++ b/compiler/rustc_middle/src/query/mod.rs @@ -1614,19 +1614,10 @@ desc { |tcx| "getting the native library for `{}`", tcx.def_path_str(def_id) } } - /// Does lifetime resolution, but does not descend into trait items. This - /// should only be used for resolving lifetimes of on trait definitions, - /// and is used to avoid cycles. Importantly, `resolve_lifetimes` still visits - /// the same lifetimes and is responsible for diagnostics. - /// See `rustc_resolve::late::lifetimes for details. - query resolve_lifetimes_trait_definition(_: LocalDefId) -> ResolveLifetimes { - arena_cache - desc { "resolving lifetimes for a trait definition" } - } /// Does lifetime resolution on items. Importantly, we can't resolve /// lifetimes directly on things like trait methods, because of trait params. /// See `rustc_resolve::late::lifetimes for details. - query resolve_lifetimes(_: LocalDefId) -> ResolveLifetimes { + query resolve_lifetimes(_: hir::OwnerId) -> ResolveLifetimes { arena_cache desc { "resolving lifetimes" } } -- 2.44.0