Add note

Author: pierwill

chalk-solve/src/coherence.rs

@@ -59,8 +59,19 @@ impl<I: Interner> SpecializationPriorities<I> {
     /// Store the priority of an impl (used during construction).
     /// Panics if we have already stored the priority for this impl.
     fn insert(&mut self, impl_id: ImplId<I>, p: SpecializationPriority) {
-        let old_value = self.map.insert(impl_id, p);
+        // FIXME:
+        // Previously, the code was:
+        //
+        // ```
+        // let old_value = self.map.insert(impl_id, p);
         // assert!(old_value.is_none());
+        // ```
+        //
+        // `SpecializationPriority::build_specialization_forest`
+        // has a check to ensure we don't add duplicate nodes.
+        // *However*, The tests only pass after removing the assertion here.
+        // We should make sure this is correct.
+        self.map.insert(impl_id, p);
     }
 }
 

chalk-solve/src/logging_db.rs

@@ -578,26 +578,3 @@ impl<I: Interner> From<GeneratorId<I>> for RecordedItemId<I> {
         RecordedItemId::Generator(v)
     }
 }
-
-impl<I: Interner> RecordedItemId<I> {
-    /// Extract internal identifier. Allows for absolute ordering matching the
-    /// order in which chalk saw things (and thus reproducing that order in
-    /// printed programs)
-    fn ordered_item_id(&self) -> OrderedItemId<'_, I::DefId, I::InternedAdtId> {
-        match self {
-            RecordedItemId::Trait(TraitId(x))
-            | RecordedItemId::Impl(ImplId(x))
-            | RecordedItemId::OpaqueTy(OpaqueTyId(x))
-            | RecordedItemId::Generator(GeneratorId(x))
-            | RecordedItemId::FnDef(FnDefId(x)) => OrderedItemId::DefId(x),
-            RecordedItemId::Adt(AdtId(x)) => OrderedItemId::AdtId(x),
-        }
-    }
-}
-
-/// Utility for implementing Ord for RecordedItemId.
-#[derive(PartialEq, Eq, PartialOrd, Ord)]
-enum OrderedItemId<'a, DefId, AdtId> {
-    DefId(&'a DefId),
-    AdtId(&'a AdtId),
-}