text: // 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"
  #include "base/stl_util.h"
  #include "base/strings/string_util.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);
  //   DEBUG_ALIAS_FOR_CSTR(name_copy, p->name, 16);
  //   CHECK(false);
  void BASE_EXPORT Alias(const void* var);
  
  }  // namespace debug
  }  // namespace base
  
  // Convenience macro that copies the null-terminated string from |c_str| into a
  // stack-allocated char array named |var_name| that holds up to |char_count|
  // characters and should be preserved in memory dumps.
  #define DEBUG_ALIAS_FOR_CSTR(var_name, c_str, char_count)   \
    char var_name[char_count];                                \
    ::base::strlcpy(var_name, (c_str), base::size(var_name)); \
    ::base::debug::Alias(var_name);
  
  #endif  // BASE_DEBUG_ALIAS_H_
  