ceph/src/boost/libs/utility/test/value_init_workaround_test.cpp

   1 // Copyright 2010, Niels Dekker.
   2 //
   3 // Distributed under the Boost Software License, Version 1.0. (See
   4 // accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // Test program for the boost::value_initialized<T> workaround.
   8 //
   9 // 17 June 2010 (Created) Niels Dekker
  10
  11 // Switch the workaround off, before inluding "value_init.hpp".
  12 #define BOOST_DETAIL_VALUE_INIT_WORKAROUND 0
  13 #include <boost/utility/value_init.hpp>
  14
  15 #include <iostream>  // For cout.
  16 #include <cstdlib>  // For EXIT_SUCCESS and EXIT_FAILURE.
  17
  18 namespace
  19 {
  20   struct empty_struct
  21   {
  22   };
  23
  24   // A POD aggregate struct derived from an empty struct.
  25   // Similar to struct Foo1 from Microsoft Visual C++ bug report 484295,
  26   // "VC++ does not value-initialize members of derived classes without
  27   // user-declared constructor", reported in 2009 by Sylvester Hesp:
  28   // https://connect.microsoft.com/VisualStudio/feedback/details/484295
  29   struct derived_struct: empty_struct
  30   {
  31     int data;
  32   };
  33
  34   bool is_value_initialized(const derived_struct& arg)
  35   {
  36     return arg.data == 0;
  37   }
  38
  39
  40   class virtual_destructor_holder
  41   {
  42   public:
  43     int i;
  44     virtual ~virtual_destructor_holder()
  45     {
  46     }
  47   };
  48
  49   bool is_value_initialized(const virtual_destructor_holder& arg)
  50   {
  51     return arg.i == 0;
  52   }
  53
  54   // Equivalent to the Stats class from GCC Bug 33916,
  55   // "Default constructor fails to initialize array members", reported in 2007 by
  56   // Michael Elizabeth Chastain: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33916
  57   // and fixed for GCC 4.2.4.
  58   class private_int_array_pair
  59   {
  60     friend bool is_value_initialized(const private_int_array_pair& arg);
  61   private:
  62     int first[12];
  63     int second[12];
  64   };
  65
  66   bool is_value_initialized(const private_int_array_pair& arg)
  67   {
  68     for ( unsigned i = 0; i < 12; ++i)
  69     {
  70       if ( (arg.first[i] != 0) || (arg.second[i] != 0) )
  71       {
  72         return false;
  73       }
  74     }
  75     return true;
  76   }
  77
  78   struct int_pair_struct
  79   {
  80     int first;
  81     int second;
  82   };
  83
  84   typedef int int_pair_struct::*ptr_to_member_type;
  85
  86   struct ptr_to_member_struct
  87   {
  88     ptr_to_member_type data;
  89   };
  90
  91   bool is_value_initialized(const ptr_to_member_struct& arg)
  92   {
  93     return arg.data == 0;
  94   }
  95
  96   template <typename T>
  97   bool is_value_initialized(const T(& arg)[2])
  98   {
  99     return
 100       is_value_initialized(arg[0]) &&
 101       is_value_initialized(arg[1]);
 102   }
 103
 104   template <typename T>
 105   bool is_value_initialized(const boost::value_initialized<T>& arg)
 106   {
 107     return is_value_initialized(arg.data());
 108   }
 109
 110   // Returns zero when the specified object is value-initializated, and one otherwise.
 111   // Prints a message to standard output if the value-initialization has failed.
 112   template <class T>
 113   unsigned failed_to_value_initialized(const T& object, const char *const object_name)
 114   {
 115     if ( is_value_initialized(object) )
 116     {
 117       return 0u;
 118     }
 119     else
 120     {
 121       std::cout << "Note: Failed to value-initialize " << object_name << '.' << std::endl;
 122       return 1u;
 123     }
 124   }
 125
 126 // A macro that passed both the name and the value of the specified object to
 127 // the function above here.
 128 #define FAILED_TO_VALUE_INITIALIZE(value) failed_to_value_initialized(value, #value)
 129
 130   // Equivalent to the dirty_stack() function from GCC Bug 33916,
 131   // "Default constructor fails to initialize array members", reported in 2007 by
 132   // Michael Elizabeth Chastain: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33916
 133   void dirty_stack()
 134   {
 135     unsigned char array_on_stack[4096];
 136     for (unsigned i = 0; i < sizeof(array_on_stack); ++i)
 137     {
 138       array_on_stack[i] = 0x11;
 139     }
 140   }
 141
 142 }
 143
 144
 145 int main()
 146 {
 147   dirty_stack();
 148
 149   // TODO More types may be added later.
 150   const unsigned num_failures =
 151     FAILED_TO_VALUE_INITIALIZE(boost::value_initialized<derived_struct>()) +
 152     FAILED_TO_VALUE_INITIALIZE(boost::value_initialized<virtual_destructor_holder[2]>()) +
 153     FAILED_TO_VALUE_INITIALIZE(boost::value_initialized<private_int_array_pair>()) +
 154     FAILED_TO_VALUE_INITIALIZE(boost::value_initialized<ptr_to_member_struct>());
 155
 156 #ifdef BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED
 157   // One or more failures are expected.
 158   return num_failures > 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 159 #else
 160   // No failures are expected.
 161   return num_failures == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 162 #endif
 163 }