add failing test

assembly/src/assembler/instruction/procedures.rs

@@ -89,7 +89,7 @@ impl Assembler {
                     // assembled, and hence be present in the `MastForest`. We currently assume that the
                     // `MastForest` contains all the procedures being called; "external procedures" only
                     // known by digest are not currently supported.
-                    mast_forest.find_root(mast_root).ok_or_else(|| {
+                    mast_forest.find_procedure_root(mast_root).ok_or_else(|| {
                         AssemblyError::UnknownExecTarget {
                             span,
                             source_file: current_source_file,
@@ -98,7 +98,7 @@ impl Assembler {
                     })?
                 }
                 InvokeKind::Call => {
-                    let callee_id = mast_forest.find_root(mast_root).unwrap_or_else(|| {
+                    let callee_id = mast_forest.find_procedure_root(mast_root).unwrap_or_else(|| {
                         // If the MAST root called isn't known to us, make it an external
                         // reference.
                         let external_node = MastNode::new_external(mast_root);

assembly/src/assembler/tests.rs

@@ -208,7 +208,10 @@ fn nested_blocks() {
         vec![before, r#if1, nested, exec_foo_bar_baz_node_id, syscall_foo_node_id],
         &mut expected_mast_forest,
     );
-    let expected_program = Program::new(expected_mast_forest.into(), combined_node_id);
 
+    let expected_program = Program::new(expected_mast_forest.into(), combined_node_id);
     assert_eq!(expected_program.hash(), program.hash());
+
+    // also check that the program has the right number of procedures
+    assert_eq!(program.num_procedures(), 3);
 }

core/src/mast/mod.rs

@@ -96,14 +96,22 @@ impl MastForest {
 
     /// Returns the [`MastNodeId`] of the procedure associated with a given digest, if any.
     #[inline(always)]
-    pub fn find_root(&self, digest: RpoDigest) -> Option<MastNodeId> {
+    pub fn find_procedure_root(&self, digest: RpoDigest) -> Option<MastNodeId> {
         self.roots.iter().find(|&&root_id| self[root_id].digest() == digest).copied()
     }
 
     /// Returns an iterator over the digest of the procedures in this MAST forest.
-    pub fn roots(&self) -> impl Iterator<Item = RpoDigest> + '_ {
+    pub fn procedure_roots(&self) -> impl Iterator<Item = RpoDigest> + '_ {
         self.roots.iter().map(|&root_id| self[root_id].digest())
     }
+
+    /// Returns the number of procedures in this MAST forest.
+    pub fn num_procedures(&self) -> u32 {
+        self.roots
+            .len()
+            .try_into()
+            .expect("MAST forest contains more than 2^32 procedures.")
+    }
 }
 
 impl Index<MastNodeId> for MastForest {

core/src/program.rs

@@ -90,8 +90,13 @@ impl Program {
 
     /// Returns the [`MastNodeId`] of the procedure root associated with a given digest, if any.
     #[inline(always)]
-    pub fn find_root(&self, digest: RpoDigest) -> Option<MastNodeId> {
-        self.mast_forest.find_root(digest)
+    pub fn find_procedure_root(&self, digest: RpoDigest) -> Option<MastNodeId> {
+        self.mast_forest.find_procedure_root(digest)
+    }
+
+    /// Returns the number of procedures in this program.
+    pub fn num_procedures(&self) -> u32 {
+        self.mast_forest.num_procedures()
     }
 }
 

processor/src/host/mast_forest_store.rs

@@ -14,7 +14,7 @@ impl MemMastForestStore {
     pub fn insert(&mut self, mast_forest: MastForest) {
         let mast_forest = Arc::new(mast_forest);
 
-        for root in mast_forest.roots() {
+        for root in mast_forest.procedure_roots() {
             self.mast_forests.insert(root, mast_forest.clone());
         }
     }

processor/src/lib.rs

@@ -262,7 +262,7 @@ where
                             root_digest: external_node.digest(),
                         },
                     )?;
-                let root_id = mast_forest.find_root(external_node.digest()).unwrap_or_else(|| panic!("Malformed host: MAST forest indexed by procedure root {} doesn't contain that root.", external_node.digest()));
+                let root_id = mast_forest.find_procedure_root(external_node.digest()).unwrap_or_else(|| panic!("Malformed host: MAST forest indexed by procedure root {} doesn't contain that root.", external_node.digest()));
 
                 let program =
                     Program::new_with_kernel(mast_forest, root_id, program.kernel().clone());
@@ -385,7 +385,7 @@ where
 
         // get dynamic code from the code block table and execute it
         let callee_id = program
-            .find_root(callee_hash.into())
+            .find_procedure_root(callee_hash.into())
             .ok_or_else(|| ExecutionError::DynamicNodeNotFound(callee_hash.into()))?;
         self.execute_mast_node(callee_id, program)?;