Recover when attempting to force a query with unknown DefPathHash.

compiler/rustc_hir/src/definitions.rs

@@ -442,14 +442,14 @@ impl Definitions {
         self.def_id_to_hir_id.iter_enumerated().map(|(k, _)| k)
     }
 
+    // FIXME(cjgillot) Stop returning an Option.
     #[inline(always)]
-    pub fn local_def_path_hash_to_def_id(&self, hash: DefPathHash) -> LocalDefId {
-        debug_assert!(hash.stable_crate_id() == self.stable_crate_id);
+    pub fn local_def_path_hash_to_def_id(&self, hash: DefPathHash) -> Option<LocalDefId> {
+        debug_assert_eq!(hash.stable_crate_id(), self.stable_crate_id);
         self.table
             .def_path_hash_to_index
             .get(&hash)
             .map(|local_def_index| LocalDefId { local_def_index })
-            .unwrap()
     }
 
     pub fn def_path_hash_to_def_index_map(&self) -> &DefPathHashMap {

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1627,7 +1627,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
     }
 
     #[inline]
-    fn def_path_hash_to_def_index(&self, hash: DefPathHash) -> DefIndex {
+    fn def_path_hash_to_def_index(&self, hash: DefPathHash) -> Option<DefIndex> {
         self.def_path_hash_map.def_path_hash_to_def_index(&hash)
     }
 

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -507,9 +507,11 @@ impl CrateStore for CStore {
         self.get_crate_data(def.krate).def_path_hash(def.index)
     }
 
-    fn def_path_hash_to_def_id(&self, cnum: CrateNum, hash: DefPathHash) -> DefId {
-        let def_index = self.get_crate_data(cnum).def_path_hash_to_def_index(hash);
-        DefId { krate: cnum, index: def_index }
+    // FIXME(cjgillot) Stop returning an Option.
+    fn def_path_hash_to_def_id(&self, hash: DefPathHash) -> Option<DefId> {
+        let cnum = self.stable_crate_id_to_crate_num(hash.stable_crate_id());
+        let def_index = self.get_crate_data(cnum).def_path_hash_to_def_index(hash)?;
+        Some(DefId { krate: cnum, index: def_index })
     }
 
     fn expn_hash_to_expn_id(

compiler/rustc_metadata/src/rmeta/def_path_hash_map.rs

@@ -12,10 +12,11 @@ crate enum DefPathHashMapRef<'tcx> {
 }
 
 impl DefPathHashMapRef<'tcx> {
+    // FIXME(cjgillot) Stop returning an Option.
     #[inline]
-    pub fn def_path_hash_to_def_index(&self, def_path_hash: &DefPathHash) -> DefIndex {
+    pub fn def_path_hash_to_def_index(&self, def_path_hash: &DefPathHash) -> Option<DefIndex> {
         match *self {
-            DefPathHashMapRef::OwnedFromMetadata(ref map) => map.get(def_path_hash).unwrap(),
+            DefPathHashMapRef::OwnedFromMetadata(ref map) => map.get(def_path_hash),
             DefPathHashMapRef::BorrowedFromTcx(_) => {
                 panic!("DefPathHashMap::BorrowedFromTcx variant only exists for serialization")
             }

compiler/rustc_middle/src/dep_graph/dep_node.rs

@@ -266,7 +266,7 @@ impl DepNodeExt for DepNode {
     /// has been removed.
     fn extract_def_id(&self, tcx: TyCtxt<'tcx>) -> Option<DefId> {
         if self.kind.fingerprint_style(tcx) == FingerprintStyle::DefPathHash {
-            Some(tcx.def_path_hash_to_def_id(DefPathHash(self.hash.into())))
+            tcx.def_path_hash_to_def_id(DefPathHash(self.hash.into()))
         } else {
             None
         }

compiler/rustc_middle/src/ty/context.rs

@@ -1305,21 +1305,23 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Converts a `DefPathHash` to its corresponding `DefId` in the current compilation
     /// session, if it still exists. This is used during incremental compilation to
     /// turn a deserialized `DefPathHash` into its current `DefId`.
-    pub fn def_path_hash_to_def_id(self, hash: DefPathHash) -> DefId {
+    // FIXME(cjgillot) Stop returning an Option.
+    pub fn def_path_hash_to_def_id(self, hash: DefPathHash) -> Option<DefId> {
         debug!("def_path_hash_to_def_id({:?})", hash);
 
         let stable_crate_id = hash.stable_crate_id();
 
         // If this is a DefPathHash from the local crate, we can look up the
         // DefId in the tcx's `Definitions`.
         if stable_crate_id == self.sess.local_stable_crate_id() {
-            self.untracked_resolutions.definitions.local_def_path_hash_to_def_id(hash).to_def_id()
+            self.untracked_resolutions
+                .definitions
+                .local_def_path_hash_to_def_id(hash)
+                .map(LocalDefId::to_def_id)
         } else {
             // If this is a DefPathHash from an upstream crate, let the CrateStore map
             // it to a DefId.
-            let cstore = &self.untracked_resolutions.cstore;
-            let cnum = cstore.stable_crate_id_to_crate_num(stable_crate_id);
-            cstore.def_path_hash_to_def_id(cnum, hash)
+            self.untracked_resolutions.cstore.def_path_hash_to_def_id(hash)
         }
     }
 

compiler/rustc_query_impl/src/on_disk_cache.rs

@@ -747,7 +747,7 @@ impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for DefId {
         // If we get to this point, then all of the query inputs were green,
         // which means that the definition with this hash is guaranteed to
         // still exist in the current compilation session.
-        Ok(d.tcx().def_path_hash_to_def_id(def_path_hash))
+        Ok(d.tcx().def_path_hash_to_def_id(def_path_hash).unwrap())
     }
 }
 

compiler/rustc_session/src/cstore.rs

@@ -193,7 +193,7 @@ pub trait CrateStore: std::fmt::Debug {
     fn stable_crate_id_to_crate_num(&self, stable_crate_id: StableCrateId) -> CrateNum;
 
     /// Fetch a DefId from a DefPathHash for a foreign crate.
-    fn def_path_hash_to_def_id(&self, cnum: CrateNum, hash: DefPathHash) -> DefId;
+    fn def_path_hash_to_def_id(&self, hash: DefPathHash) -> Option<DefId>;
     fn expn_hash_to_expn_id(
         &self,
         sess: &Session,