Change default behavior to drop function names from reference map.

PiperOrigin-RevId: 866522706

Author: jnthntatum

checker/checker_options.h

@@ -85,6 +85,16 @@ struct CheckerOptions {
   // expressions that compound nesting e.g.
   // type5(T)->type(type(type(type(type(T)))))); type5(type5(T)) -> type10(T)
   int max_type_decl_nesting = 13;
+
+  // If true, the checker will include the resolved function name in the
+  // reference map for the function call expr.
+  //
+  // If false, the function name will be empty and implied by the overload id
+  // set. This matches the behavior in cel-go and cel-java.
+  //
+  // Temporary flag to allow rolling out the change. No functional changes to
+  // evaluation behavior in either mode.
+  bool enable_function_name_in_reference = false;
 };
 
 }  // namespace cel

checker/internal/type_checker_impl.cc

@@ -1259,7 +1259,9 @@ class ResolveRewriter : public AstRewriterBase {
       const FunctionDecl* decl = iter->second.decl;
       const bool needs_rewrite = iter->second.namespace_rewrite;
       auto& ast_ref = reference_map_[expr.id()];
-      ast_ref.set_name(decl->name());
+      if (options_.enable_function_name_in_reference) {
+        ast_ref.set_name(decl->name());
+      }
       for (const auto& overload : decl->overloads()) {
         ast_ref.mutable_overload_id().push_back(overload.id());
       }

checker/internal/type_checker_impl_test.cc

@@ -140,23 +140,20 @@ MATCHER_P(IsVariableReference, var_name, "") {
 
 MATCHER_P2(IsFunctionReference, fn_name, overloads, "") {
   const Reference& reference = arg;
-  if (reference.name() != fn_name) {
-    *result_listener << "expected: " << fn_name
-                     << "\nactual: " << reference.name();
-  }
 
   absl::flat_hash_set<std::string> got_overload_set(
       reference.overload_id().begin(), reference.overload_id().end());
   absl::flat_hash_set<std::string> want_overload_set(overloads.begin(),
                                                      overloads.end());
 
   if (got_overload_set != want_overload_set) {
-    *result_listener << "expected overload_ids: "
+    *result_listener << "reference to " << fn_name << "\n"
+                     << "expected overload_ids: "
                      << absl::StrJoin(want_overload_set, ",")
                      << "\nactual: " << absl::StrJoin(got_overload_set, ",");
   }
 
-  return reference.name() == fn_name && got_overload_set == want_overload_set;
+  return got_overload_set == want_overload_set;
 }
 
 absl::Status RegisterMinimalBuiltins(google::protobuf::Arena* absl_nonnull arena,