Add type checking to some native function arguments

runtime/lib/error.cc

 // Copyright (c) 2012, 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 "lib/error.h"
 
 #include "vm/bootstrap_natives.h"
 #include "vm/exceptions.h"
 #include "vm/object_store.h"
 #include "vm/runtime_entry.h"
 #include "vm/stack_frame.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, trace_type_checks, false, "Trace runtime type checks.");
 
 // Allocate and throw a new AssertionError.
 // Arg0: index of the first token of the failed assertion.
 // Arg1: index of the first token after the failed assertion.
 // Return value: none, throws an exception.
 DEFINE_NATIVE_ENTRY(AssertionError_throwNew, 2) {
+  // No need to type check the arguments. This function can only be called
+  // internally from the VM.
   intptr_t assertion_start = Smi::CheckedHandle(arguments->At(0)).Value();
   intptr_t assertion_end = Smi::CheckedHandle(arguments->At(1)).Value();
 
   // Allocate a new instance of type AssertionError.
   const Instance& assertion_error = Instance::Handle(
       Exceptions::NewInstance("AssertionError"));
 
   // Initialize 'url', 'line', and 'column' fields.
   DartFrameIterator iterator;
   iterator.NextFrame();  // Skip native call.
@@ skipping 16 matching lines @@
 
 
 // Allocate and throw a new TypeError.
 // Arg0: index of the token of the failed type check.
 // Arg1: src value.
 // Arg2: dst type name.
 // Arg3: dst name.
 // Arg4: malformed type error message.
 // Return value: none, throws an exception.
 DEFINE_NATIVE_ENTRY(TypeError_throwNew, 5) {
+  // No need to type check the arguments. This function can only be called
+  // internally from the VM.
   intptr_t location = Smi::CheckedHandle(arguments->At(0)).Value();
   const Instance& src_value = Instance::CheckedHandle(arguments->At(1));
   const String& dst_type_name = String::CheckedHandle(arguments->At(2));
   const String& dst_name = String::CheckedHandle(arguments->At(3));
   const String& malformed_error = String::CheckedHandle(arguments->At(4));
   const String& src_type_name =
       String::Handle(Type::Handle(src_value.GetType()).Name());
   Exceptions::CreateAndThrowTypeError(location, src_type_name,
                                       dst_type_name, dst_name, malformed_error);
 }
@@ skipping 50 matching lines @@
   intptr_t line, column;
   script.GetTokenLocation(call_pos, &line, &column);
   Exceptions::SetField(resolution_exception, cls, "failedResolutionLine",
                        String::Handle(script.GetLine(line)));
 
   Exceptions::Throw(resolution_exception);
   UNREACHABLE();
 }
 
 }  // namespace dart