Make the "sticky error" an Error instead of a String.

runtime/vm/code_generator_x64.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 "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/code_generator.h"
 
 #include "lib/error.h"
@@ skipping 2293 matching lines @@
     instantiator_class = outer_function.signature_class();
   } else {
     instantiator_class = outer_function.owner();
   }
   if (instantiator_class.NumTypeParameters() == 0) {
     // The type arguments are compile time constants.
     AbstractTypeArguments& type_arguments = AbstractTypeArguments::ZoneHandle();
     // TODO(regis): Temporary type should be allocated in new gen heap.
     Type& type = Type::Handle(
         Type::NewParameterizedType(instantiator_class, type_arguments));
-    String& errmsg = String::Handle();
+    Error& error = Error::Handle();
     type ^= ClassFinalizer::FinalizeAndCanonicalizeType(instantiator_class,
                                                         type,
-                                                        &errmsg);
-    if (!errmsg.IsNull()) {
-      ErrorMsg(token_index, errmsg.ToCString());
+                                                        &error);
+    if (!error.IsNull()) {
+      ErrorMsg(token_index, error.ToErrorCString());
     }
     type_arguments = type.arguments();
     __ PushObject(type_arguments);
   } else {
     ASSERT(parsed_function().instantiator() != NULL);
     parsed_function().instantiator()->Visit(this);
     if (!outer_function.IsFactory()) {
       __ popq(RAX);  // Pop instantiator.
       // The instantiator is the receiver of the caller, which is not a factory.
       // The receiver cannot be null; extract its AbstractTypeArguments object.
@@ skipping 454 matching lines @@
                                          intptr_t token_index) {
   pc_descriptors_list_->AddDescriptor(kind,
                                       assembler_->CodeSize(),
                                       node_id,
                                       token_index,
                                       state()->try_index());
 }
 
 
 void CodeGenerator::ErrorMsg(intptr_t token_index, const char* format, ...) {
-  const intptr_t kMessageBufferSize = 512;
-  char message_buffer[kMessageBufferSize];
   va_list args;
   va_start(args, format);
   const Class& cls = Class::Handle(parsed_function_.function().owner());
   const Script& script = Script::Handle(cls.script());
-  Parser::FormatMessage(script, token_index, "Error",
-                        message_buffer, kMessageBufferSize,
-                        format, args);
+  const Error& error = Error::Handle(
+      Parser::FormatError(script, token_index, "Error", format, args));
   va_end(args);
-  Isolate::Current()->long_jump_base()->Jump(1, message_buffer);
+  Isolate::Current()->long_jump_base()->Jump(1, error);
   UNREACHABLE();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64