Minror cleanups from PR feedback

This was also rebased in the meantime, this is the only new commit
since the rebase onto feat/dif-info.

src/types/mod.rs

@@ -549,9 +549,7 @@ pub enum ObjectUseInfo {
 
 /// Newtype around a collection of [`ObjectCandidate`] structs.
 ///
-/// This abstracts away some common operations needed on this collection.  Because it needs
-/// to be passed through objects implementing the [`CacheItemRequest`] trait while avoiding
-/// copying and yet being able to mutate, we need to have inner mutability.
+/// This abstracts away some common operations needed on this collection.
 ///
 /// [`CacheItemRequest`]: ../actors/common/cache/trait.CacheItemRequest.html
 #[derive(Clone, Debug, Default, Serialize, Deserialize, Eq, PartialEq)]

src/types/objects.rs

@@ -20,7 +20,8 @@ impl ObjectUseInfo {
 
 impl From<Vec<ObjectCandidate>> for AllObjectCandidates {
     fn from(mut source: Vec<ObjectCandidate>) -> Self {
-        source.sort_by_key(|candidate| (candidate.source.clone(), candidate.location.clone()));
+        source
+            .sort_by_cached_key(|candidate| (candidate.source.clone(), candidate.location.clone()));
         Self(source)
     }
 }
@@ -39,9 +40,6 @@ impl AllObjectCandidates {
             Ok(index) => {
                 if let Some(mut candidate) = self.0.get_mut(index) {
                     candidate.debug = info;
-                } else {
-                    // TODO(flub): remove before PR
-                    panic!("wtf");
                 }
             }
             Err(_) => {