Auto merge of #93373 - spastorino:def_id_to_hir_id_refactor, r=oli-obk

Store def_id_to_hir_id as variant in hir_owner.

If hir_owner is Owner(_), the LocalDefId is pointing to an owner, so the ItemLocalId is 0.
If the HIR node does not exist, we store Phantom.
Otherwise, we store the HirId associated to the LocalDefId.

Related to #89278

r? `@oli-obk`

11 files changed, 116 insertions, 95 deletions

diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index ed3abbd5b4d..8b4a0840df5 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -105,12 +105,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> T {
         let old_len = self.in_scope_lifetimes.len();
 
-        let parent_generics =
-            match self.owners[parent_hir_id].as_ref().unwrap().node().expect_item().kind {
-                hir::ItemKind::Impl(hir::Impl { ref generics, .. })
-                | hir::ItemKind::Trait(_, _, ref generics, ..) => generics.params,
-                _ => &[],
-            };
+        let parent_generics = match self.owners[parent_hir_id].unwrap().node().expect_item().kind {
+            hir::ItemKind::Impl(hir::Impl { ref generics, .. })
+            | hir::ItemKind::Trait(_, _, ref generics, ..) => generics.params,
+            _ => &[],
+        };
         let lt_def_names = parent_generics.iter().filter_map(|param| match param.kind {
             hir::GenericParamKind::Lifetime { .. } => Some(param.name.normalize_to_macros_2_0()),
             _ => None,
@@ -480,6 +479,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
                             .node_id_to_hir_id
                             .insert(new_node_id, hir::HirId::make_owner(new_id));
                         debug_assert!(_old.is_none());
+                        self.owners.ensure_contains_elem(new_id, || hir::MaybeOwner::Phantom);
+                        let _old = std::mem::replace(
+                            &mut self.owners[new_id],
+                            hir::MaybeOwner::NonOwner(hir::HirId::make_owner(new_id)),
+                        );
+                        debug_assert!(matches!(_old, hir::MaybeOwner::Phantom));
                         continue;
                     };
                     let ident = *ident;
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 32cec3a295a..f21f0b895ad 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -98,7 +98,7 @@ struct LoweringContext<'a, 'hir: 'a> {
     arena: &'hir Arena<'hir>,
 
     /// The items being lowered are collected here.
-    owners: IndexVec<LocalDefId, Option<hir::OwnerInfo<'hir>>>,
+    owners: IndexVec<LocalDefId, hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>>>,
     /// Bodies inside the owner being lowered.
     bodies: Vec<(hir::ItemLocalId, &'hir hir::Body<'hir>)>,
     /// Attributes inside the owner being lowered.
@@ -291,7 +291,8 @@ pub fn lower_crate<'a, 'hir>(
 ) -> &'hir hir::Crate<'hir> {
     let _prof_timer = sess.prof.verbose_generic_activity("hir_lowering");
 
-    let owners = IndexVec::from_fn_n(|_| None, resolver.definitions().def_index_count());
+    let owners =
+        IndexVec::from_fn_n(|_| hir::MaybeOwner::Phantom, resolver.definitions().def_index_count());
     LoweringContext {
         sess,
         resolver,
@@ -402,19 +403,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
         let hir_hash = self.compute_hir_hash();
 
-        let mut def_id_to_hir_id = IndexVec::default();
-
-        for (node_id, hir_id) in self.node_id_to_hir_id.into_iter_enumerated() {
-            if let Some(def_id) = self.resolver.opt_local_def_id(node_id) {
-                if def_id_to_hir_id.len() <= def_id.index() {
-                    def_id_to_hir_id.resize(def_id.index() + 1, None);
-                }
-                def_id_to_hir_id[def_id] = hir_id;
-            }
-        }
-
-        self.resolver.definitions().init_def_id_to_hir_id_mapping(def_id_to_hir_id);
-
         let krate = hir::Crate { owners: self.owners, hir_hash };
         self.arena.alloc(krate)
     }
@@ -427,7 +415,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             .owners
             .iter_enumerated()
             .filter_map(|(def_id, info)| {
-                let info = info.as_ref()?;
+                let info = info.as_owner()?;
                 let def_path_hash = definitions.def_path_hash(def_id);
                 Some((def_path_hash, info))
             })
@@ -469,8 +457,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         self.current_hir_id_owner = current_owner;
         self.item_local_id_counter = current_local_counter;
 
-        let _old = self.owners.insert(def_id, info);
-        debug_assert!(_old.is_none());
+        self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
+        self.owners[def_id] = hir::MaybeOwner::Owner(self.arena.alloc(info));
 
         def_id
     }
@@ -488,6 +476,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     None
                 } else {
                     let def_id = self.resolver.opt_local_def_id(node_id)?;
+                    self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
+                    if let o @ hir::MaybeOwner::Phantom = &mut self.owners[def_id] {
+                        // Do not override a `MaybeOwner::Owner` that may already here.
+                        *o = hir::MaybeOwner::NonOwner(hir_id);
+                    }
                     Some((hir_id.local_id, def_id))
                 }
             })
diff --git a/compiler/rustc_hir/src/definitions.rs b/compiler/rustc_hir/src/definitions.rs
index 74d6b05ca5f..d655f12f5e1 100644
--- a/compiler/rustc_hir/src/definitions.rs
+++ b/compiler/rustc_hir/src/definitions.rs
@@ -7,7 +7,6 @@
 pub use crate::def_id::DefPathHash;
 use crate::def_id::{CrateNum, DefIndex, LocalDefId, StableCrateId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use crate::def_path_hash_map::DefPathHashMap;
-use crate::hir;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::StableHasher;
@@ -101,13 +100,6 @@ impl DefPathTable {
 pub struct Definitions {
     table: DefPathTable,
 
-    /// Only [`LocalDefId`]s for items and item-like are HIR owners.
-    /// The associated `HirId` has a `local_id` of `0`.
-    /// Generic parameters and closures are also assigned a `LocalDefId` but are not HIR owners.
-    /// Their `HirId`s are defined by their position while lowering the enclosing owner.
-    // FIXME(cjgillot) Some `LocalDefId`s from `use` items are dropped during lowering and lack a `HirId`.
-    pub(super) def_id_to_hir_id: IndexVec<LocalDefId, Option<hir::HirId>>,
-
     /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
     expansions_that_defined: FxHashMap<LocalDefId, ExpnId>,
 
@@ -322,12 +314,6 @@ impl Definitions {
         })
     }
 
-    #[inline]
-    #[track_caller]
-    pub fn local_def_id_to_hir_id(&self, id: LocalDefId) -> hir::HirId {
-        self.def_id_to_hir_id[id].unwrap()
-    }
-
     /// Adds a root definition (no parent) and a few other reserved definitions.
     pub fn new(stable_crate_id: StableCrateId, crate_span: Span) -> Definitions {
         let key = DefKey {
@@ -354,7 +340,6 @@ impl Definitions {
 
         Definitions {
             table,
-            def_id_to_hir_id: Default::default(),
             expansions_that_defined: Default::default(),
             def_id_to_span,
             stable_crate_id,
@@ -406,20 +391,6 @@ impl Definitions {
         def_id
     }
 
-    /// Initializes the `LocalDefId` to `HirId` mapping once it has been generated during
-    /// AST to HIR lowering.
-    pub fn init_def_id_to_hir_id_mapping(
-        &mut self,
-        mapping: IndexVec<LocalDefId, Option<hir::HirId>>,
-    ) {
-        assert!(
-            self.def_id_to_hir_id.is_empty(),
-            "trying to initialize `LocalDefId` <-> `HirId` mappings twice"
-        );
-
-        self.def_id_to_hir_id = mapping;
-    }
-
     pub fn expansion_that_defined(&self, id: LocalDefId) -> ExpnId {
         self.expansions_that_defined.get(&id).copied().unwrap_or_else(ExpnId::root)
     }
@@ -431,7 +402,7 @@ impl Definitions {
     }
 
     pub fn iter_local_def_id(&self) -> impl Iterator<Item = LocalDefId> + '_ {
-        self.def_id_to_hir_id.iter_enumerated().map(|(k, _)| k)
+        self.table.def_path_hashes.indices().map(|local_def_index| LocalDefId { local_def_index })
     }
 
     #[inline(always)]
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index a0ed72c9e9e..67398c80f36 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -711,6 +711,15 @@ pub struct OwnerNodes<'tcx> {
     pub local_id_to_def_id: SortedMap<ItemLocalId, LocalDefId>,
 }
 
+impl<'tcx> OwnerNodes<'tcx> {
+    pub fn node(&self) -> OwnerNode<'tcx> {
+        use rustc_index::vec::Idx;
+        let node = self.nodes[ItemLocalId::new(0)].as_ref().unwrap().node;
+        let node = node.as_owner().unwrap(); // Indexing must ensure it is an OwnerNode.
+        node
+    }
+}
+
 /// Full information resulting from lowering an AST node.
 #[derive(Debug, HashStable_Generic)]
 pub struct OwnerInfo<'hir> {
@@ -728,10 +737,39 @@ pub struct OwnerInfo<'hir> {
 impl<'tcx> OwnerInfo<'tcx> {
     #[inline]
     pub fn node(&self) -> OwnerNode<'tcx> {
-        use rustc_index::vec::Idx;
-        let node = self.nodes.nodes[ItemLocalId::new(0)].as_ref().unwrap().node;
-        let node = node.as_owner().unwrap(); // Indexing must ensure it is an OwnerNode.
-        node
+        self.nodes.node()
+    }
+}
+
+#[derive(Copy, Clone, Debug, HashStable_Generic)]
+pub enum MaybeOwner<T> {
+    Owner(T),
+    NonOwner(HirId),
+    /// Used as a placeholder for unused LocalDefId.
+    Phantom,
+}
+
+impl<T> MaybeOwner<T> {
+    pub fn as_owner(self) -> Option<T> {
+        match self {
+            MaybeOwner::Owner(i) => Some(i),
+            MaybeOwner::NonOwner(_) | MaybeOwner::Phantom => None,
+        }
+    }
+
+    pub fn map<U>(self, f: impl FnOnce(T) -> U) -> MaybeOwner<U> {
+        match self {
+            MaybeOwner::Owner(i) => MaybeOwner::Owner(f(i)),
+            MaybeOwner::NonOwner(hir_id) => MaybeOwner::NonOwner(hir_id),
+            MaybeOwner::Phantom => MaybeOwner::Phantom,
+        }
+    }
+
+    pub fn unwrap(self) -> T {
+        match self {
+            MaybeOwner::Owner(i) => i,
+            MaybeOwner::NonOwner(_) | MaybeOwner::Phantom => panic!("Not a HIR owner"),
+        }
     }
 }
 
@@ -743,7 +781,7 @@ impl<'tcx> OwnerInfo<'tcx> {
 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
 #[derive(Debug)]
 pub struct Crate<'hir> {
-    pub owners: IndexVec<LocalDefId, Option<OwnerInfo<'hir>>>,
+    pub owners: IndexVec<LocalDefId, MaybeOwner<&'hir OwnerInfo<'hir>>>,
     pub hir_hash: Fingerprint,
 }
 
diff --git a/compiler/rustc_hir/src/hir_id.rs b/compiler/rustc_hir/src/hir_id.rs
index 5b486819c35..dee391b9cce 100644
--- a/compiler/rustc_hir/src/hir_id.rs
+++ b/compiler/rustc_hir/src/hir_id.rs
@@ -31,6 +31,11 @@ impl HirId {
     }
 
     #[inline]
+    pub fn is_owner(self) -> bool {
+        self.local_id.index() == 0
+    }
+
+    #[inline]
     pub fn make_owner(owner: LocalDefId) -> Self {
         Self { owner, local_id: ItemLocalId::from_u32(0) }
     }
diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs
index 1885df6ac5d..649cb34bd5f 100644
--- a/compiler/rustc_middle/src/hir/map/mod.rs
+++ b/compiler/rustc_middle/src/hir/map/mod.rs
@@ -162,7 +162,7 @@ impl<'hir> Map<'hir> {
 
     pub fn items(&self) -> impl Iterator<Item = &'hir Item<'hir>> + 'hir {
         let krate = self.krate();
-        krate.owners.iter().filter_map(|owner| match owner.as_ref()?.node() {
+        krate.owners.iter().filter_map(|owner| match owner.as_owner()?.node() {
             OwnerNode::Item(item) => Some(item),
             _ => None,
         })
@@ -205,7 +205,8 @@ impl<'hir> Map<'hir> {
             Some(hir_id.owner)
         } else {
             self.tcx
-                .hir_owner_nodes(hir_id.owner)?
+                .hir_owner_nodes(hir_id.owner)
+                .as_owner()?
                 .local_id_to_def_id
                 .get(&hir_id.local_id)
                 .copied()
@@ -214,8 +215,7 @@ impl<'hir> Map<'hir> {
 
     #[inline]
     pub fn local_def_id_to_hir_id(&self, def_id: LocalDefId) -> HirId {
-        // FIXME(#85914) is this access safe for incr. comp.?
-        self.tcx.untracked_resolutions.definitions.local_def_id_to_hir_id(def_id)
+        self.tcx.local_def_id_to_hir_id(def_id)
     }
 
     pub fn iter_local_def_id(&self) -> impl Iterator<Item = LocalDefId> + '_ {
@@ -321,7 +321,7 @@ impl<'hir> Map<'hir> {
         if id.local_id == ItemLocalId::from_u32(0) {
             Some(self.tcx.hir_owner_parent(id.owner))
         } else {
-            let owner = self.tcx.hir_owner_nodes(id.owner)?;
+            let owner = self.tcx.hir_owner_nodes(id.owner).as_owner()?;
             let node = owner.nodes[id.local_id].as_ref()?;
             let hir_id = HirId { owner: id.owner, local_id: node.parent };
             Some(hir_id)
@@ -338,7 +338,7 @@ impl<'hir> Map<'hir> {
             let owner = self.tcx.hir_owner(id.owner)?;
             Some(owner.node.into())
         } else {
-            let owner = self.tcx.hir_owner_nodes(id.owner)?;
+            let owner = self.tcx.hir_owner_nodes(id.owner).as_owner()?;
             let node = owner.nodes[id.local_id].as_ref()?;
             Some(node.node)
         }
@@ -522,7 +522,7 @@ impl<'hir> Map<'hir> {
             .owners
             .iter_enumerated()
             .flat_map(move |(owner, owner_info)| {
-                let bodies = &owner_info.as_ref()?.nodes.bodies;
+                let bodies = &owner_info.as_owner()?.nodes.bodies;
                 Some(bodies.iter().map(move |&(local_id, _)| {
                     let hir_id = HirId { owner, local_id };
                     let body_id = BodyId { hir_id };
@@ -539,7 +539,7 @@ impl<'hir> Map<'hir> {
 
         par_iter(&self.krate().owners.raw).enumerate().for_each(|(owner, owner_info)| {
             let owner = LocalDefId::new(owner);
-            if let Some(owner_info) = owner_info {
+            if let MaybeOwner::Owner(owner_info) = owner_info {
                 par_iter(owner_info.nodes.bodies.range(..)).for_each(|(local_id, _)| {
                     let hir_id = HirId { owner, local_id: *local_id };
                     let body_id = BodyId { hir_id };
@@ -601,7 +601,7 @@ impl<'hir> Map<'hir> {
     pub fn walk_attributes(self, visitor: &mut impl Visitor<'hir>) {
         let krate = self.krate();
         for (owner, info) in krate.owners.iter_enumerated() {
-            if let Some(info) = info {
+            if let MaybeOwner::Owner(info) = info {
                 for (local_id, attrs) in info.attrs.map.iter() {
                     let id = HirId { owner, local_id: *local_id };
                     for a in *attrs {
@@ -625,7 +625,7 @@ impl<'hir> Map<'hir> {
         V: itemlikevisit::ItemLikeVisitor<'hir>,
     {
         let krate = self.krate();
-        for owner in krate.owners.iter().filter_map(Option::as_ref) {
+        for owner in krate.owners.iter().filter_map(|i| i.as_owner()) {
             match owner.node() {
                 OwnerNode::Item(item) => visitor.visit_item(item),
                 OwnerNode::ForeignItem(item) => visitor.visit_foreign_item(item),
@@ -642,12 +642,14 @@ impl<'hir> Map<'hir> {
         V: itemlikevisit::ParItemLikeVisitor<'hir> + Sync + Send,
     {
         let krate = self.krate();
-        par_for_each_in(&krate.owners.raw, |owner| match owner.as_ref().map(OwnerInfo::node) {
-            Some(OwnerNode::Item(item)) => visitor.visit_item(item),
-            Some(OwnerNode::ForeignItem(item)) => visitor.visit_foreign_item(item),
-            Some(OwnerNode::ImplItem(item)) => visitor.visit_impl_item(item),
-            Some(OwnerNode::TraitItem(item)) => visitor.visit_trait_item(item),
-            Some(OwnerNode::Crate(_)) | None => {}
+        par_for_each_in(&krate.owners.raw, |owner| match owner.map(OwnerInfo::node) {
+            MaybeOwner::Owner(OwnerNode::Item(item)) => visitor.visit_item(item),
+            MaybeOwner::Owner(OwnerNode::ForeignItem(item)) => visitor.visit_foreign_item(item),
+            MaybeOwner::Owner(OwnerNode::ImplItem(item)) => visitor.visit_impl_item(item),
+            MaybeOwner::Owner(OwnerNode::TraitItem(item)) => visitor.visit_trait_item(item),
+            MaybeOwner::Owner(OwnerNode::Crate(_))
+            | MaybeOwner::NonOwner(_)
+            | MaybeOwner::Phantom => {}
         })
     }
 
@@ -1121,7 +1123,7 @@ pub(super) fn crate_hash(tcx: TyCtxt<'_>, crate_num: CrateNum) -> Svh {
             .owners
             .iter_enumerated()
             .filter_map(|(def_id, info)| {
-                let _ = info.as_ref()?;
+                let _ = info.as_owner()?;
                 let def_path_hash = definitions.def_path_hash(def_id);
                 let span = definitions.def_span(def_id);
                 debug_assert_eq!(span.parent(), None);
diff --git a/compiler/rustc_middle/src/hir/mod.rs b/compiler/rustc_middle/src/hir/mod.rs
index b4c7bb7eba7..1053f0cefbe 100644
--- a/compiler/rustc_middle/src/hir/mod.rs
+++ b/compiler/rustc_middle/src/hir/mod.rs
@@ -65,20 +65,27 @@ pub fn provide(providers: &mut Providers) {
     providers.crate_hash = map::crate_hash;
     providers.hir_module_items = map::hir_module_items;
     providers.hir_owner = |tcx, id| {
-        let owner = tcx.hir_crate(()).owners.get(id)?.as_ref()?;
+        let owner = tcx.hir_crate(()).owners.get(id)?.as_owner()?;
         let node = owner.node();
         Some(Owner { node, hash_without_bodies: owner.nodes.hash_without_bodies })
     };
-    providers.hir_owner_nodes = |tcx, id| tcx.hir_crate(()).owners[id].as_ref().map(|i| &i.nodes);
+    providers.local_def_id_to_hir_id = |tcx, id| {
+        let owner = tcx.hir_crate(()).owners[id].map(|_| ());
+        match owner {
+            MaybeOwner::Owner(_) => HirId::make_owner(id),
+            MaybeOwner::Phantom => bug!("No HirId for {:?}", id),
+            MaybeOwner::NonOwner(hir_id) => hir_id,
+        }
+    };
+    providers.hir_owner_nodes = |tcx, id| tcx.hir_crate(()).owners[id].map(|i| &i.nodes);
     providers.hir_owner_parent = |tcx, id| {
         // Accessing the def_key is ok since its value is hashed as part of `id`'s DefPathHash.
         let parent = tcx.untracked_resolutions.definitions.def_key(id).parent;
         let parent = parent.map_or(CRATE_HIR_ID, |local_def_index| {
             let def_id = LocalDefId { local_def_index };
-            let mut parent_hir_id =
-                tcx.untracked_resolutions.definitions.local_def_id_to_hir_id(def_id);
+            let mut parent_hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
             if let Some(local_id) =
-                tcx.hir_crate(()).owners[parent_hir_id.owner].as_ref().unwrap().parenting.get(&id)
+                tcx.hir_crate(()).owners[parent_hir_id.owner].unwrap().parenting.get(&id)
             {
                 parent_hir_id.local_id = *local_id;
             }
@@ -87,7 +94,7 @@ pub fn provide(providers: &mut Providers) {
         parent
     };
     providers.hir_attrs =
-        |tcx, id| tcx.hir_crate(()).owners[id].as_ref().map_or(AttributeMap::EMPTY, |o| &o.attrs);
+        |tcx, id| tcx.hir_crate(()).owners[id].as_owner().map_or(AttributeMap::EMPTY, |o| &o.attrs);
     providers.source_span = |tcx, def_id| tcx.resolutions(()).definitions.def_span(def_id);
     providers.def_span = |tcx, def_id| tcx.hir().span_if_local(def_id).unwrap_or(DUMMY_SP);
     providers.fn_arg_names = |tcx, id| {
@@ -111,4 +118,6 @@ pub fn provide(providers: &mut Providers) {
         let id = id.expect_local();
         tcx.resolutions(()).definitions.expansion_that_defined(id)
     };
+    providers.in_scope_traits_map =
+        |tcx, id| tcx.hir_crate(()).owners[id].as_owner().map(|owner_info| &owner_info.trait_map);
 }
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 54391bd649e..12ece9e6afb 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -56,6 +56,14 @@ rustc_queries! {
         desc { |tcx| "HIR owner of `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
+    /// Gives access to the HIR ID for the given `LocalDefId` owner `key`.
+    ///
+    /// This can be conveniently accessed by methods on `tcx.hir()`.
+    /// Avoid calling this query directly.
+    query local_def_id_to_hir_id(key: LocalDefId) -> hir::HirId {
+        desc { |tcx| "HIR ID of `{}`", tcx.def_path_str(key.to_def_id()) }
+    }
+
     /// Gives access to the HIR node's parent for the HIR owner `key`.
     ///
     /// This can be conveniently accessed by methods on `tcx.hir()`.
@@ -68,7 +76,7 @@ rustc_queries! {
     ///
     /// This can be conveniently accessed by methods on `tcx.hir()`.
     /// Avoid calling this query directly.
-    query hir_owner_nodes(key: LocalDefId) -> Option<&'tcx hir::OwnerNodes<'tcx>> {
+    query hir_owner_nodes(key: LocalDefId) -> hir::MaybeOwner<&'tcx hir::OwnerNodes<'tcx>> {
         desc { |tcx| "HIR owner items in `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index d063494f2bc..5dae4b9e4c9 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -2875,8 +2875,6 @@ fn ptr_eq<T, U>(t: *const T, u: *const U) -> bool {
 }
 
 pub fn provide(providers: &mut ty::query::Providers) {
-    providers.in_scope_traits_map =
-        |tcx, id| tcx.hir_crate(()).owners[id].as_ref().map(|owner_info| &owner_info.trait_map);
     providers.resolutions = |tcx, ()| &tcx.untracked_resolutions;
     providers.module_reexports =
         |tcx, id| tcx.resolutions(()).reexport_map.get(&id).map(|v| &v[..]);
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 82455654a88..2bb9f48f9b7 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -579,7 +579,7 @@ fn hash_mir_source<'tcx>(tcx: TyCtxt<'tcx>, hir_body: &'tcx rustc_hir::Body<'tcx
     let mut hcx = tcx.create_no_span_stable_hashing_context();
     let mut stable_hasher = StableHasher::new();
     let owner = hir_body.id().hir_id.owner;
-    let bodies = &tcx.hir_owner_nodes(owner).as_ref().unwrap().bodies;
+    let bodies = &tcx.hir_owner_nodes(owner).unwrap().bodies;
     hcx.with_hir_bodies(false, owner, bodies, |hcx| {
         hir_body.value.hash_stable(hcx, &mut stable_hasher)
     });
diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs
index 4c7bdb33fb8..6ef85c426be 100644
--- a/compiler/rustc_resolve/src/late/lifetimes.rs
+++ b/compiler/rustc_resolve/src/late/lifetimes.rs
@@ -1019,15 +1019,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
                     let hir_id = self.tcx.hir().local_def_id_to_hir_id(def_id);
                     // Ensure that the parent of the def is an item, not HRTB
                     let parent_id = self.tcx.hir().get_parent_node(hir_id);
-                    // FIXME(cjgillot) Can this check be replaced by
-                    // `let parent_is_item = parent_id.is_owner();`?
-                    let parent_is_item = if let Some(parent_def_id) = parent_id.as_owner() {
-                        matches!(self.tcx.hir().krate().owners.get(parent_def_id), Some(Some(_)),)
-                    } else {
-                        false
-                    };
-
-                    if !parent_is_item {
+                    if !parent_id.is_owner() {
                         if !self.trait_definition_only {
                             struct_span_err!(
                                 self.tcx.sess,