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