If programmer mistakes the number of arguments, VM throws noSuchMethod. Extend reporting to repor...

runtime/lib/object.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/bootstrap_natives.h"
 
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 
@@ skipping 11 matching lines @@
   if (instance.IsNull()) {
     GrowableArray<const Object*> args;
     Exceptions::ThrowByType(Exceptions::kNullPointer, args);
   }
   GET_NATIVE_ARGUMENT(String, function_name, arguments->At(1));
   GET_NATIVE_ARGUMENT(Array, func_args, arguments->At(2));
   GrowableArray<const Object*> dart_arguments(3);
   dart_arguments.Add(&instance);
   dart_arguments.Add(&function_name);
   dart_arguments.Add(&func_args);
+  // Report if a function with same name (but different arguments) has been
+  // found.
+  Class& instance_class = Class::Handle(instance.clazz());
+  Function& function =
+      Function::Handle(instance_class.LookupDynamicFunction(function_name));
+  while (function.IsNull()) {
+    instance_class = instance_class.SuperClass();
+    if (instance_class.IsNull()) break;
+    function = instance_class.LookupDynamicFunction(function_name);
+  }
+  if (!function.IsNull()) {
+    String& tmp = String::Handle();
+    String& extra_message = String::Handle();
+    tmp = String::NewSymbol("\nFound '");
+    extra_message = String::Concat(tmp, function_name);
+    tmp = String::NewSymbol("(");
+    extra_message = String::Concat(extra_message, tmp);
+    const int total_num_paramaters =
+        function.num_fixed_parameters() + function.num_optional_parameters();
+    // 0 is the receiver ('this'), skip it.
+    for (int i = 1; i < total_num_paramaters; i++) {
+      if (i > 1) {
+        tmp = String::NewSymbol(", ");
+        extra_message = String::Concat(extra_message, tmp);
+      }
+      tmp = function.ParameterNameAt(i);
+      extra_message = String::Concat(extra_message, tmp);
+    }
+    tmp = String::NewSymbol(")'");
+    extra_message = String::Concat(extra_message, tmp);
+    dart_arguments.Add(&extra_message);
+  }
   Exceptions::ThrowByType(Exceptions::kNoSuchMethod, dart_arguments);
 }
 
 }  // namespace dart