Auto merge of #66131 - eddyb:local-def-id, r=petrochenkov

rustc: use LocalDefId instead of DefIndex where possible.

That is, wherever `DefIndex` always referred to a "def" in the local crate, I replaced it with `LocalDefId`.
While `LocalDefId` already existed, it wasn't used a lot, but I hope I'm on the right track.

Unresolved questions:
* [x] ~~should `LocalDefId` implement `rustc_index::Idx`?~~
  * ~~this would get rid of a couple more `DefIndex` uses~~
* [x] ~~should `LocalDefId` be encoded/decoded as just a `DefIndex`?~~
  * ~~right now it's a bit messy, `LocalDefId` encodes/decodes like `DefId`~~
* [x] ~~should `DefId::assert_local` be named something else, like `expect_local`?~~

A future PR should change `tcx.hir().local_def_id(...)` to return `LocalDefId` instead of `DefId`, as changing it in this PR would be too noisy.

r? @michaelwoerister cc @nikomatsakis @petrochenkov @Zoxc

Author: bors

src/librustc/dep_graph/dep_node.rs

@@ -63,7 +63,7 @@ use crate::ty::subst::SubstsRef;
 use crate::ty::{self, ParamEnvAnd, Ty, TyCtxt};
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX};
+use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX};
 use rustc_hir::HirId;
 use rustc_span::symbol::Symbol;
 use std::fmt;
@@ -413,19 +413,19 @@ impl<'tcx> DepNodeParams<'tcx> for DefId {
     }
 }
 
-impl<'tcx> DepNodeParams<'tcx> for DefIndex {
+impl<'tcx> DepNodeParams<'tcx> for LocalDefId {
     const CAN_RECONSTRUCT_QUERY_KEY: bool = true;
 
     fn to_fingerprint(&self, tcx: TyCtxt<'_>) -> Fingerprint {
-        tcx.hir().definitions().def_path_hash(*self).0
+        self.to_def_id().to_fingerprint(tcx)
     }
 
     fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String {
-        tcx.def_path_str(DefId::local(*self))
+        self.to_def_id().to_debug_str(tcx)
     }
 
     fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> {
-        dep_node.extract_def_id(tcx).map(|id| id.index)
+        dep_node.extract_def_id(tcx).map(|id| id.expect_local())
     }
 }
 
@@ -477,7 +477,7 @@ impl<'tcx> DepNodeParams<'tcx> for HirId {
     fn to_fingerprint(&self, tcx: TyCtxt<'_>) -> Fingerprint {
         let HirId { owner, local_id } = *self;
 
-        let def_path_hash = tcx.def_path_hash(DefId::local(owner));
+        let def_path_hash = tcx.def_path_hash(owner.to_def_id());
         let local_id = Fingerprint::from_smaller_hash(local_id.as_u32().into());
 
         def_path_hash.0.combine(local_id)

src/librustc/dep_graph/graph.rs

@@ -902,7 +902,7 @@ impl DepGraph {
 
 fn def_id_corresponds_to_hir_dep_node(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
     let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
-    def_id.index == hir_id.owner
+    def_id.index == hir_id.owner.local_def_index
 }
 
 /// A "work product" is an intermediate result that we save into the

src/librustc/hir/map/collector.rs

@@ -10,7 +10,7 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::svh::Svh;
 use rustc_hir as hir;
 use rustc_hir::def_id::CRATE_DEF_INDEX;
-use rustc_hir::def_id::{DefIndex, LOCAL_CRATE};
+use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::*;
 use rustc_index::vec::{Idx, IndexVec};
@@ -30,12 +30,12 @@ pub(super) struct NodeCollector<'a, 'hir> {
     /// Source map
     source_map: &'a SourceMap,
 
-    map: IndexVec<DefIndex, HirOwnerData<'hir>>,
+    map: IndexVec<LocalDefId, HirOwnerData<'hir>>,
 
     /// The parent of this node
     parent_node: hir::HirId,
 
-    current_dep_node_owner: DefIndex,
+    current_dep_node_owner: LocalDefId,
 
     definitions: &'a definitions::Definitions,
 
@@ -98,7 +98,8 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
         definitions: &'a definitions::Definitions,
         mut hcx: StableHashingContext<'a>,
     ) -> NodeCollector<'a, 'hir> {
-        let root_mod_def_path_hash = definitions.def_path_hash(CRATE_DEF_INDEX);
+        let root_mod_def_path_hash =
+            definitions.def_path_hash(LocalDefId { local_def_index: CRATE_DEF_INDEX });
 
         let mut hir_body_nodes = Vec::new();
 
@@ -126,7 +127,7 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
             krate,
             source_map: sess.source_map(),
             parent_node: hir::CRATE_HIR_ID,
-            current_dep_node_owner: CRATE_DEF_INDEX,
+            current_dep_node_owner: LocalDefId { local_def_index: CRATE_DEF_INDEX },
             definitions,
             hcx,
             hir_body_nodes,
@@ -148,7 +149,7 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
         crate_disambiguator: CrateDisambiguator,
         cstore: &dyn CrateStore,
         commandline_args_hash: u64,
-    ) -> (IndexVec<DefIndex, HirOwnerData<'hir>>, Svh) {
+    ) -> (IndexVec<LocalDefId, HirOwnerData<'hir>>, Svh) {
         // Insert bodies into the map
         for (id, body) in self.krate.bodies.iter() {
             let bodies = &mut self.map[id.hir_id.owner].with_bodies.as_mut().unwrap().bodies;
@@ -244,8 +245,8 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
             assert_eq!(self.definitions.node_to_hir_id(node_id), hir_id);
 
             if hir_id.owner != self.current_dep_node_owner {
-                let node_str = match self.definitions.opt_def_index(node_id) {
-                    Some(def_index) => self.definitions.def_path(def_index).to_string_no_crate(),
+                let node_str = match self.definitions.opt_local_def_id(node_id) {
+                    Some(def_id) => self.definitions.def_path(def_id).to_string_no_crate(),
                     None => format!("{:?}", node),
                 };
 
@@ -285,7 +286,7 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
         F: FnOnce(&mut Self, Fingerprint),
     >(
         &mut self,
-        dep_node_owner: DefIndex,
+        dep_node_owner: LocalDefId,
         item_like: &T,
         f: F,
     ) {
@@ -341,7 +342,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
         debug!("visit_item: {:?}", i);
         debug_assert_eq!(
             i.hir_id.owner,
-            self.definitions.opt_def_index(self.definitions.hir_to_node_id(i.hir_id)).unwrap()
+            self.definitions.opt_local_def_id(self.definitions.hir_to_node_id(i.hir_id)).unwrap()
         );
         self.with_dep_node_owner(i.hir_id.owner, i, |this, hash| {
             this.insert_with_hash(i.span, i.hir_id, Node::Item(i), hash);
@@ -373,7 +374,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     fn visit_trait_item(&mut self, ti: &'hir TraitItem<'hir>) {
         debug_assert_eq!(
             ti.hir_id.owner,
-            self.definitions.opt_def_index(self.definitions.hir_to_node_id(ti.hir_id)).unwrap()
+            self.definitions.opt_local_def_id(self.definitions.hir_to_node_id(ti.hir_id)).unwrap()
         );
         self.with_dep_node_owner(ti.hir_id.owner, ti, |this, hash| {
             this.insert_with_hash(ti.span, ti.hir_id, Node::TraitItem(ti), hash);
@@ -387,7 +388,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     fn visit_impl_item(&mut self, ii: &'hir ImplItem<'hir>) {
         debug_assert_eq!(
             ii.hir_id.owner,
-            self.definitions.opt_def_index(self.definitions.hir_to_node_id(ii.hir_id)).unwrap()
+            self.definitions.opt_local_def_id(self.definitions.hir_to_node_id(ii.hir_id)).unwrap()
         );
         self.with_dep_node_owner(ii.hir_id.owner, ii, |this, hash| {
             this.insert_with_hash(ii.span, ii.hir_id, Node::ImplItem(ii), hash);
@@ -506,10 +507,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     }
 
     fn visit_macro_def(&mut self, macro_def: &'hir MacroDef<'hir>) {
-        let node_id = self.definitions.hir_to_node_id(macro_def.hir_id);
-        let def_index = self.definitions.opt_def_index(node_id).unwrap();
-
-        self.with_dep_node_owner(def_index, macro_def, |this, hash| {
+        self.with_dep_node_owner(macro_def.hir_id.owner, macro_def, |this, hash| {
             this.insert_with_hash(
                 macro_def.span,
                 macro_def.hir_id,