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
is_value_initialized(const derived_struct & arg)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;
~virtual_destructor_holder()44 virtual ~virtual_destructor_holder()
45 {
46 }
47 };
48
is_value_initialized(const virtual_destructor_holder & arg)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
is_value_initialized(const private_int_array_pair & arg)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
is_value_initialized(const ptr_to_member_struct & arg)91 bool is_value_initialized(const ptr_to_member_struct& arg)
92 {
93 return arg.data == 0;
94 }
95
96 template <typename T>
is_value_initialized(const T (& arg)[2])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>
is_value_initialized(const boost::value_initialized<T> & arg)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>
failed_to_value_initialized(const T & object,const char * const object_name)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
dirty_stack()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
main()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 }
164