Do not use C++ const references in the C interface.

runtime/vm/dart_api_impl.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 "include/dart_api.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart.h"
@@ skipping 287 matching lines @@
   ASSERT(state != NULL);
   ApiLocalScope* scope = state->top_scope();
   ASSERT(scope != NULL);
   return scope->zone().Reallocate(ptr, old_size, new_size);
 }
 
 
 // --- Handles ---
 
 
-DART_EXPORT bool Dart_IsError(const Dart_Handle& handle) {
+DART_EXPORT bool Dart_IsError(Dart_Handle handle) {
   DARTSCOPE(Isolate::Current());
   const Object& obj = Object::Handle(Api::UnwrapHandle(handle));
   return obj.IsApiError();
 }
 
 
 static const char* MakeUnhandledExceptionCString(
     const UnhandledException& uhe) {
   const Instance& exception = Instance::Handle(uhe.exception());
   Object& strtmp = Object::Handle(DartLibraryCalls::ToString(exception));
@@ skipping 14 matching lines @@
   const char* format = "Unhandled exception:\n%s\n%s";
   int len = (strlen(exc_str) + strlen(stack_str) + strlen(format)
              - 4    // Two '%s'
              + 1);  // '\0'
   char* buffer = reinterpret_cast<char*>(Api::Allocate(len));
   OS::SNPrint(buffer, len, format, exc_str, stack_str);
   return buffer;
 }
 
 
-DART_EXPORT const char* Dart_GetError(const Dart_Handle& handle) {
+DART_EXPORT const char* Dart_GetError(Dart_Handle handle) {
   DARTSCOPE(Isolate::Current());
 
   const Object& obj = Object::Handle(Api::UnwrapHandle(handle));
   if (!obj.IsApiError()) {
     return "";
   }
   ApiError& failure = ApiError::Handle();
   failure ^= obj.raw();
   const Object& data = Object::Handle(failure.data());
   if (data.IsString()) {
@@ skipping 2181 matching lines @@
     }
     delete debug_region;
   } else {
     *buffer = NULL;
     *buffer_size = 0;
   }
 }
 
 
 }  // namespace dart