chore: add comments and clean up code

clarity/src/vm/callables.rs

@@ -212,7 +212,8 @@ impl DefinedFunction {
                         );
                     }
                     // Since this Clarity 1 contract may be called from a Clarity 2 contract,
-                    // we need to handle Clarity 2 values as well.
+                    // we need to handle Clarity 2 values as well. Clarity 2 contracts can only
+                    // be executed in epoch 2.1, so we only need to handle `CallableType` here.
                     (
                         TypeSignature::CallableType(CallableSubtype::Trait(_)),
                         Value::CallableContract(CallableData {

clarity/src/vm/contexts.rs

@@ -1838,6 +1838,9 @@ impl ContractContext {
         &self.clarity_version
     }
 
+    /// Canonicalize the types for the specified epoch. Only functions and
+    /// defined traits are exposed externally, so other types are not
+    /// canonicalized.
     pub fn canonicalize_types(&mut self, epoch: &StacksEpochId) {
         for (_, function) in self.functions.iter_mut() {
             function.canonicalize_types(epoch);

src/clarity_vm/tests/contracts.rs

@@ -396,6 +396,7 @@ fn trait_invocation_205_with_stored_principal() {
     });
 }
 
+/// Publish a trait in epoch 2.05 and then invoke it in epoch 2.1.
 #[test]
 fn trait_invocation_cross_epoch() {
     let mut sim = ClarityTestSim::new();
@@ -475,6 +476,9 @@ fn trait_invocation_cross_epoch() {
     });
 }
 
+/// Publish a trait that includes another trait in one of its functions in
+/// epoch 2.05 and then invoke it in epoch 2.1. Test variations of epoch and
+/// Clarity versions for the contract that uses the trait.
 #[test]
 fn trait_with_trait_invocation_cross_epoch() {
     let mut sim = ClarityTestSim::new();

testnet/stacks-node/src/tests/epoch_21.rs

@@ -4878,7 +4878,6 @@ fn trait_invocation_cross_epoch() {
                     parsed.txid(),
                     tx.get("raw_result").unwrap().as_str().unwrap()
                 );
-                //   eprintln!("{}", tx);
             }
         }
     }