rustc: introduce DefId::as_local(self) -> Option<LocalDefId> and use it.

src/librustc/hir/map/hir_id_validator.rs

@@ -3,7 +3,7 @@ use crate::ty::TyCtxt;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sync::{par_iter, Lock, ParallelIterator};
 use rustc_hir as hir;
-use rustc_hir::def_id::{DefId, DefIndex, CRATE_DEF_INDEX};
+use rustc_hir::def_id::{DefIndex, LocalDefId, CRATE_DEF_INDEX};
 use rustc_hir::intravisit;
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_hir::{HirId, ItemLocalId};
@@ -113,14 +113,18 @@ impl<'a, 'hir> HirIdValidator<'a, 'hir> {
                 missing_items.push(format!(
                     "[local_id: {}, owner: {}]",
                     local_id,
-                    self.hir_map.def_path(DefId::local(owner_def_index)).to_string_no_crate()
+                    self.hir_map
+                        .def_path(LocalDefId { local_def_index: owner_def_index })
+                        .to_string_no_crate()
                 ));
             }
             self.error(|| {
                 format!(
                     "ItemLocalIds not assigned densely in {}. \
                 Max ItemLocalId = {}, missing IDs = {:?}; seens IDs = {:?}",
-                    self.hir_map.def_path(DefId::local(owner_def_index)).to_string_no_crate(),
+                    self.hir_map
+                        .def_path(LocalDefId { local_def_index: owner_def_index })
+                        .to_string_no_crate(),
                     max,
                     missing_items,
                     self.hir_ids_seen
@@ -159,8 +163,10 @@ impl<'a, 'hir> intravisit::Visitor<'hir> for HirIdValidator<'a, 'hir> {
                 format!(
                     "HirIdValidator: The recorded owner of {} is {} instead of {}",
                     self.hir_map.node_to_string(hir_id),
-                    self.hir_map.def_path(DefId::local(hir_id.owner)).to_string_no_crate(),
-                    self.hir_map.def_path(DefId::local(owner)).to_string_no_crate()
+                    self.hir_map.def_path(hir_id.owner_local_def_id()).to_string_no_crate(),
+                    self.hir_map
+                        .def_path(LocalDefId { local_def_index: owner })
+                        .to_string_no_crate()
                 )
             });
         }

src/librustc/hir/map/mod.rs

@@ -188,18 +188,16 @@ impl<'hir> Map<'hir> {
         &self.tcx.definitions
     }
 
-    pub fn def_key(&self, def_id: DefId) -> DefKey {
-        assert!(def_id.is_local());
-        self.tcx.definitions.def_key(def_id.index)
+    pub fn def_key(&self, def_id: LocalDefId) -> DefKey {
+        self.tcx.definitions.def_key(def_id.local_def_index)
     }
 
     pub fn def_path_from_hir_id(&self, id: HirId) -> Option<DefPath> {
-        self.opt_local_def_id(id).map(|def_id| self.def_path(def_id))
+        self.opt_local_def_id(id).map(|def_id| self.def_path(def_id.expect_local()))
     }
 
-    pub fn def_path(&self, def_id: DefId) -> DefPath {
-        assert!(def_id.is_local());
-        self.tcx.definitions.def_path(def_id.index)
+    pub fn def_path(&self, def_id: LocalDefId) -> DefPath {
+        self.tcx.definitions.def_path(def_id.local_def_index)
     }
 
     #[inline]

src/librustc/ich/hcx.rs

@@ -123,8 +123,8 @@ impl<'a> StableHashingContext<'a> {
 
     #[inline]
     pub fn def_path_hash(&self, def_id: DefId) -> DefPathHash {
-        if def_id.is_local() {
-            self.definitions.def_path_hash(def_id.index)
+        if let Some(def_id) = def_id.as_local() {
+            self.definitions.def_path_hash(def_id.local_def_index)
         } else {
             self.cstore.def_path_hash(def_id)
         }

src/librustc/ty/context.rs

@@ -1261,7 +1261,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn def_key(self, id: DefId) -> hir_map::DefKey {
-        if id.is_local() { self.hir().def_key(id) } else { self.cstore.def_key(id) }
+        if let Some(id) = id.as_local() { self.hir().def_key(id) } else { self.cstore.def_key(id) }
     }
 
     /// Converts a `DefId` into its fully expanded `DefPath` (every
@@ -1270,7 +1270,11 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Note that if `id` is not local to this crate, the result will
     ///  be a non-local `DefPath`.
     pub fn def_path(self, id: DefId) -> hir_map::DefPath {
-        if id.is_local() { self.hir().def_path(id) } else { self.cstore.def_path(id) }
+        if let Some(id) = id.as_local() {
+            self.hir().def_path(id)
+        } else {
+            self.cstore.def_path(id)
+        }
     }
 
     /// Returns whether or not the crate with CrateNum 'cnum'
@@ -1281,8 +1285,8 @@ impl<'tcx> TyCtxt<'tcx> {
 
     #[inline]
     pub fn def_path_hash(self, def_id: DefId) -> hir_map::DefPathHash {
-        if def_id.is_local() {
-            self.definitions.def_path_hash(def_id.index)
+        if let Some(def_id) = def_id.as_local() {
+            self.definitions.def_path_hash(def_id.local_def_index)
         } else {
             self.cstore.def_path_hash(def_id)
         }

src/librustc_mir/borrow_check/nll.rs

@@ -272,7 +272,7 @@ pub(in crate::borrow_check) fn compute_regions<'cx, 'tcx>(
     // Dump facts if requested.
     let polonius_output = all_facts.and_then(|all_facts| {
         if infcx.tcx.sess.opts.debugging_opts.nll_facts {
-            let def_path = infcx.tcx.hir().def_path(def_id);
+            let def_path = infcx.tcx.def_path(def_id);
             let dir_path =
                 PathBuf::from("nll-facts").join(def_path.to_filename_friendly_no_crate());
             all_facts.write_to_dir(dir_path, location_table).unwrap();

src/librustc_passes/entry.rs

@@ -34,7 +34,7 @@ struct EntryContext<'a, 'tcx> {
 impl<'a, 'tcx> ItemLikeVisitor<'tcx> for EntryContext<'a, 'tcx> {
     fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
         let def_id = self.map.local_def_id(item.hir_id);
-        let def_key = self.map.def_key(def_id);
+        let def_key = self.map.def_key(def_id.expect_local());
         let at_root = def_key.parent == Some(CRATE_DEF_INDEX);
         find_item(item, self, at_root);
     }

src/librustc_span/def_id.rs

@@ -163,10 +163,14 @@ impl DefId {
         self.krate == LOCAL_CRATE
     }
 
+    #[inline]
+    pub fn as_local(self) -> Option<LocalDefId> {
+        if self.is_local() { Some(LocalDefId { local_def_index: self.index }) } else { None }
+    }
+
     #[inline]
     pub fn expect_local(self) -> LocalDefId {
-        assert!(self.is_local());
-        LocalDefId { local_def_index: self.index }
+        self.as_local().unwrap_or_else(|| panic!("DefId::expect_local: `{:?}` isn't local", self))
     }
 
     pub fn is_top_level_module(self) -> bool {

src/librustc_typeck/check/mod.rs

@@ -638,9 +638,8 @@ pub struct InheritedBuilder<'tcx> {
 
 impl Inherited<'_, 'tcx> {
     pub fn build(tcx: TyCtxt<'tcx>, def_id: DefId) -> InheritedBuilder<'tcx> {
-        let hir_id_root = if def_id.is_local() {
-            let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
-            DefId::local(hir_id.owner)
+        let hir_id_root = if let Some(def_id) = def_id.as_local() {
+            tcx.hir().local_def_id_to_hir_id(def_id).owner_def_id()
         } else {
             def_id
         };