1 files changed, 346 insertions, 0 deletions
diff --git a/compiler/rustc_ast_lowering/src/index.rs b/compiler/rustc_ast_lowering/src/index.rs
new file mode 100644
index 000000000..d5af74d47
--- /dev/null
+++ b/compiler/rustc_ast_lowering/src/index.rs
@@ -0,0 +1,346 @@
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::sorted_map::SortedMap;
+use rustc_hir as hir;
+use rustc_hir::def_id::LocalDefId;
+use rustc_hir::definitions;
+use rustc_hir::intravisit::{self, Visitor};
+use rustc_hir::*;
+use rustc_index::vec::{Idx, IndexVec};
+use rustc_middle::span_bug;
+use rustc_session::Session;
+use rustc_span::source_map::SourceMap;
+use rustc_span::{Span, DUMMY_SP};
+
+use tracing::debug;
+
+/// A visitor that walks over the HIR and collects `Node`s into a HIR map.
+pub(super) struct NodeCollector<'a, 'hir> {
+    /// Source map
+    source_map: &'a SourceMap,
+    bodies: &'a SortedMap<ItemLocalId, &'hir Body<'hir>>,
+
+    /// Outputs
+    nodes: IndexVec<ItemLocalId, Option<ParentedNode<'hir>>>,
+    parenting: FxHashMap<LocalDefId, ItemLocalId>,
+
+    /// The parent of this node
+    parent_node: hir::ItemLocalId,
+
+    owner: LocalDefId,
+
+    definitions: &'a definitions::Definitions,
+}
+
+#[tracing::instrument(level = "debug", skip(sess, definitions, bodies))]
+pub(super) fn index_hir<'hir>(
+    sess: &Session,
+    definitions: &definitions::Definitions,
+    item: hir::OwnerNode<'hir>,
+    bodies: &SortedMap<ItemLocalId, &'hir Body<'hir>>,
+) -> (IndexVec<ItemLocalId, Option<ParentedNode<'hir>>>, FxHashMap<LocalDefId, ItemLocalId>) {
+    let mut nodes = IndexVec::new();
+    // This node's parent should never be accessed: the owner's parent is computed by the
+    // hir_owner_parent query.  Make it invalid (= ItemLocalId::MAX) to force an ICE whenever it is
+    // used.
+    nodes.push(Some(ParentedNode { parent: ItemLocalId::INVALID, node: item.into() }));
+    let mut collector = NodeCollector {
+        source_map: sess.source_map(),
+        definitions,
+        owner: item.def_id(),
+        parent_node: ItemLocalId::new(0),
+        nodes,
+        bodies,
+        parenting: FxHashMap::default(),
+    };
+
+    match item {
+        OwnerNode::Crate(citem) => {
+            collector.visit_mod(&citem, citem.spans.inner_span, hir::CRATE_HIR_ID)
+        }
+        OwnerNode::Item(item) => collector.visit_item(item),
+        OwnerNode::TraitItem(item) => collector.visit_trait_item(item),
+        OwnerNode::ImplItem(item) => collector.visit_impl_item(item),
+        OwnerNode::ForeignItem(item) => collector.visit_foreign_item(item),
+    };
+
+    (collector.nodes, collector.parenting)
+}
+
+impl<'a, 'hir> NodeCollector<'a, 'hir> {
+    #[tracing::instrument(level = "debug", skip(self))]
+    fn insert(&mut self, span: Span, hir_id: HirId, node: Node<'hir>) {
+        debug_assert_eq!(self.owner, hir_id.owner);
+        debug_assert_ne!(hir_id.local_id.as_u32(), 0);
+
+        // Make sure that the DepNode of some node coincides with the HirId
+        // owner of that node.
+        if cfg!(debug_assertions) {
+            if hir_id.owner != self.owner {
+                span_bug!(
+                    span,
+                    "inconsistent DepNode at `{:?}` for `{:?}`: \
+                     current_dep_node_owner={} ({:?}), hir_id.owner={} ({:?})",
+                    self.source_map.span_to_diagnostic_string(span),
+                    node,
+                    self.definitions.def_path(self.owner).to_string_no_crate_verbose(),
+                    self.owner,
+                    self.definitions.def_path(hir_id.owner).to_string_no_crate_verbose(),
+                    hir_id.owner,
+                )
+            }
+        }
+
+        self.nodes.insert(hir_id.local_id, ParentedNode { parent: self.parent_node, node: node });
+    }
+
+    fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_node_id: HirId, f: F) {
+        debug_assert_eq!(parent_node_id.owner, self.owner);
+        let parent_node = self.parent_node;
+        self.parent_node = parent_node_id.local_id;
+        f(self);
+        self.parent_node = parent_node;
+    }
+
+    fn insert_nested(&mut self, item: LocalDefId) {
+        self.parenting.insert(item, self.parent_node);
+    }
+}
+
+impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
+    /// Because we want to track parent items and so forth, enable
+    /// deep walking so that we walk nested items in the context of
+    /// their outer items.
+
+    fn visit_nested_item(&mut self, item: ItemId) {
+        debug!("visit_nested_item: {:?}", item);
+        self.insert_nested(item.def_id);
+    }
+
+    fn visit_nested_trait_item(&mut self, item_id: TraitItemId) {
+        self.insert_nested(item_id.def_id);
+    }
+
+    fn visit_nested_impl_item(&mut self, item_id: ImplItemId) {
+        self.insert_nested(item_id.def_id);
+    }
+
+    fn visit_nested_foreign_item(&mut self, foreign_id: ForeignItemId) {
+        self.insert_nested(foreign_id.def_id);
+    }
+
+    fn visit_nested_body(&mut self, id: BodyId) {
+        debug_assert_eq!(id.hir_id.owner, self.owner);
+        let body = self.bodies[&id.hir_id.local_id];
+        self.visit_body(body);
+    }
+
+    fn visit_param(&mut self, param: &'hir Param<'hir>) {
+        let node = Node::Param(param);
+        self.insert(param.pat.span, param.hir_id, node);
+        self.with_parent(param.hir_id, |this| {
+            intravisit::walk_param(this, param);
+        });
+    }
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    fn visit_item(&mut self, i: &'hir Item<'hir>) {
+        debug_assert_eq!(i.def_id, self.owner);
+        self.with_parent(i.hir_id(), |this| {
+            if let ItemKind::Struct(ref struct_def, _) = i.kind {
+                // If this is a tuple or unit-like struct, register the constructor.
+                if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
+                    this.insert(i.span, ctor_hir_id, Node::Ctor(struct_def));
+                }
+            }
+            intravisit::walk_item(this, i);
+        });
+    }
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    fn visit_foreign_item(&mut self, fi: &'hir ForeignItem<'hir>) {
+        debug_assert_eq!(fi.def_id, self.owner);
+        self.with_parent(fi.hir_id(), |this| {
+            intravisit::walk_foreign_item(this, fi);
+        });
+    }
+
+    fn visit_generic_param(&mut self, param: &'hir GenericParam<'hir>) {
+        self.insert(param.span, param.hir_id, Node::GenericParam(param));
+        intravisit::walk_generic_param(self, param);
+    }
+
+    fn visit_const_param_default(&mut self, param: HirId, ct: &'hir AnonConst) {
+        self.with_parent(param, |this| {
+            intravisit::walk_const_param_default(this, ct);
+        })
+    }
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    fn visit_trait_item(&mut self, ti: &'hir TraitItem<'hir>) {
+        debug_assert_eq!(ti.def_id, self.owner);
+        self.with_parent(ti.hir_id(), |this| {
+            intravisit::walk_trait_item(this, ti);
+        });
+    }
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    fn visit_impl_item(&mut self, ii: &'hir ImplItem<'hir>) {
+        debug_assert_eq!(ii.def_id, self.owner);
+        self.with_parent(ii.hir_id(), |this| {
+            intravisit::walk_impl_item(this, ii);
+        });
+    }
+
+    fn visit_pat(&mut self, pat: &'hir Pat<'hir>) {
+        self.insert(pat.span, pat.hir_id, Node::Pat(pat));
+
+        self.with_parent(pat.hir_id, |this| {
+            intravisit::walk_pat(this, pat);
+        });
+    }
+
+    fn visit_arm(&mut self, arm: &'hir Arm<'hir>) {
+        let node = Node::Arm(arm);
+
+        self.insert(arm.span, arm.hir_id, node);
+
+        self.with_parent(arm.hir_id, |this| {
+            intravisit::walk_arm(this, arm);
+        });
+    }
+
+    fn visit_anon_const(&mut self, constant: &'hir AnonConst) {
+        self.insert(DUMMY_SP, constant.hir_id, Node::AnonConst(constant));
+
+        self.with_parent(constant.hir_id, |this| {
+            intravisit::walk_anon_const(this, constant);
+        });
+    }
+
+    fn visit_expr(&mut self, expr: &'hir Expr<'hir>) {
+        self.insert(expr.span, expr.hir_id, Node::Expr(expr));
+
+        self.with_parent(expr.hir_id, |this| {
+            intravisit::walk_expr(this, expr);
+        });
+    }
+
+    fn visit_stmt(&mut self, stmt: &'hir Stmt<'hir>) {
+        self.insert(stmt.span, stmt.hir_id, Node::Stmt(stmt));
+
+        self.with_parent(stmt.hir_id, |this| {
+            intravisit::walk_stmt(this, stmt);
+        });
+    }
+
+    fn visit_path_segment(&mut self, path_span: Span, path_segment: &'hir PathSegment<'hir>) {
+        if let Some(hir_id) = path_segment.hir_id {
+            self.insert(path_span, hir_id, Node::PathSegment(path_segment));
+        }
+        intravisit::walk_path_segment(self, path_span, path_segment);
+    }
+
+    fn visit_ty(&mut self, ty: &'hir Ty<'hir>) {
+        self.insert(ty.span, ty.hir_id, Node::Ty(ty));
+
+        self.with_parent(ty.hir_id, |this| {
+            intravisit::walk_ty(this, ty);
+        });
+    }
+
+    fn visit_infer(&mut self, inf: &'hir InferArg) {
+        self.insert(inf.span, inf.hir_id, Node::Infer(inf));
+
+        self.with_parent(inf.hir_id, |this| {
+            intravisit::walk_inf(this, inf);
+        });
+    }
+
+    fn visit_trait_ref(&mut self, tr: &'hir TraitRef<'hir>) {
+        self.insert(tr.path.span, tr.hir_ref_id, Node::TraitRef(tr));
+
+        self.with_parent(tr.hir_ref_id, |this| {
+            intravisit::walk_trait_ref(this, tr);
+        });
+    }
+
+    fn visit_fn(
+        &mut self,
+        fk: intravisit::FnKind<'hir>,
+        fd: &'hir FnDecl<'hir>,
+        b: BodyId,
+        s: Span,
+        id: HirId,
+    ) {
+        assert_eq!(self.owner, id.owner);
+        assert_eq!(self.parent_node, id.local_id);
+        intravisit::walk_fn(self, fk, fd, b, s, id);
+    }
+
+    fn visit_block(&mut self, block: &'hir Block<'hir>) {
+        self.insert(block.span, block.hir_id, Node::Block(block));
+        self.with_parent(block.hir_id, |this| {
+            intravisit::walk_block(this, block);
+        });
+    }
+
+    fn visit_local(&mut self, l: &'hir Local<'hir>) {
+        self.insert(l.span, l.hir_id, Node::Local(l));
+        self.with_parent(l.hir_id, |this| {
+            intravisit::walk_local(this, l);
+        })
+    }
+
+    fn visit_lifetime(&mut self, lifetime: &'hir Lifetime) {
+        self.insert(lifetime.span, lifetime.hir_id, Node::Lifetime(lifetime));
+    }
+
+    fn visit_variant(&mut self, v: &'hir Variant<'hir>, g: &'hir Generics<'hir>, item_id: HirId) {
+        self.insert(v.span, v.id, Node::Variant(v));
+        self.with_parent(v.id, |this| {
+            // Register the constructor of this variant.
+            if let Some(ctor_hir_id) = v.data.ctor_hir_id() {
+                this.insert(v.span, ctor_hir_id, Node::Ctor(&v.data));
+            }
+            intravisit::walk_variant(this, v, g, item_id);
+        });
+    }
+
+    fn visit_field_def(&mut self, field: &'hir FieldDef<'hir>) {
+        self.insert(field.span, field.hir_id, Node::Field(field));
+        self.with_parent(field.hir_id, |this| {
+            intravisit::walk_field_def(this, field);
+        });
+    }
+
+    fn visit_assoc_type_binding(&mut self, type_binding: &'hir TypeBinding<'hir>) {
+        self.insert(type_binding.span, type_binding.hir_id, Node::TypeBinding(type_binding));
+        self.with_parent(type_binding.hir_id, |this| {
+            intravisit::walk_assoc_type_binding(this, type_binding)
+        })
+    }
+
+    fn visit_trait_item_ref(&mut self, ii: &'hir TraitItemRef) {
+        // Do not visit the duplicate information in TraitItemRef. We want to
+        // map the actual nodes, not the duplicate ones in the *Ref.
+        let TraitItemRef { id, ident: _, kind: _, span: _ } = *ii;
+
+        self.visit_nested_trait_item(id);
+    }
+
+    fn visit_impl_item_ref(&mut self, ii: &'hir ImplItemRef) {
+        // Do not visit the duplicate information in ImplItemRef. We want to
+        // map the actual nodes, not the duplicate ones in the *Ref.
+        let ImplItemRef { id, ident: _, kind: _, span: _, trait_item_def_id: _ } = *ii;
+
+        self.visit_nested_impl_item(id);
+    }
+
+    fn visit_foreign_item_ref(&mut self, fi: &'hir ForeignItemRef) {
+        // Do not visit the duplicate information in ForeignItemRef. We want to
+        // map the actual nodes, not the duplicate ones in the *Ref.
+        let ForeignItemRef { id, ident: _, span: _ } = *fi;
+
+        self.visit_nested_foreign_item(id);
+    }
+}