base/debug/alias.h

// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_DEBUG_ALIAS_H_
#define BASE_DEBUG_ALIAS_H_

#include "base/base_export.h"

namespace base {
namespace debug {

// Make the optimizer think that var is aliased. This is to prevent it from
// optimizing out local variables that would not otherwise be live at the point
// of a potential crash.
// base::debug::Alias should only be used for local variables, not globals,
// object members, or function return values - these must be copied to locals if
// you want to ensure they are recorded in crash dumps.
// Note that if the local variable is a pointer then its value will be retained
// but the memory that it points to will probably not be saved in the crash
// dump - by default only stack memory is saved. Therefore the aliasing
// technique is usually only worthwhile with non-pointer variables. If you have
// a pointer to an object and you want to retain the object's state you need to
// copy the object or its fields to local variables. Example usage:
//   int last_error = err_;
//   base::debug::Alias(&last_error);
//   char name_copy[16];
//   strncpy(name_copy, p->name, sizeof(name_copy) - 1);
//   name_copy[sizeof(name_copy) - 1] = '\0';
//   base::debug::Alias(name_copy);
//   CHECK(false);
void BASE_EXPORT Alias(const void* var);

}  // namespace debug
}  // namespace base

#endif  // BASE_DEBUG_ALIAS_H_