1// DR 339
2//
3// Test of the use of casts with SFINAE
4
5// Boilerplate helpers
6typedef char yes_type;
7struct no_type { char data[2]; };
8
9template<typename T> T create_a();
10template<typename T> struct type { };
11
12template<bool, typename T = void> struct enable_if { typedef T type; };
13template<typename T> struct enable_if<false, T> { };
14
15#define JOIN( X, Y ) DO_JOIN( X, Y )
16#define DO_JOIN( X, Y ) DO_JOIN2(X,Y)
17#define DO_JOIN2( X, Y ) X##Y
18
19#define CHECK_CAST(CastKind)                                            \
20template<typename T, typename U>                                        \
21 typename enable_if<(sizeof((JOIN(CastKind,_cast)<U>(create_a<T>())), 0) > 0), \
22                   yes_type>::type                                      \
23  JOIN(check_,JOIN(CastKind,_cast))(int);                               \
24                                                                        \
25template<typename T, typename U>                                        \
26  no_type JOIN(check_,JOIN(CastKind,_cast))(...);                       \
27                                                                        \
28template<typename T, typename U>                                        \
29struct JOIN(has_,JOIN(CastKind,_cast))                                  \
30{                                                                       \
31  static const bool value =                                             \
32    (sizeof(JOIN(check_,JOIN(CastKind,_cast))<T, U>(0)) == sizeof(yes_type)); \
33}
34
35template<typename T, typename U>
36typename enable_if<(sizeof(((U)create_a<T>()), 0) > 0), yes_type>::type
37  check_c_cast(int);
38
39template<typename T, typename U> no_type check_c_cast(...);
40
41template<typename T, typename U>
42struct has_c_cast
43{
44  static const bool value =
45    (sizeof(check_c_cast<T, U>(0)) == sizeof(yes_type));
46};
47
48#ifdef __GXX_EXPERIMENTAL_CXX0X__
49#  define STATIC_ASSERT(Expr) static_assert(Expr, #Expr)
50#else
51#  define STATIC_ASSERT(Expr) int JOIN(a,__LINE__)[Expr? 1 : -1]
52#endif
53
54CHECK_CAST(static);
55CHECK_CAST(dynamic);
56CHECK_CAST(const);
57CHECK_CAST(reinterpret);
58
59struct X { virtual void f(); };
60struct Y { operator bool(); };
61struct Z : public X { };
62
63STATIC_ASSERT((has_static_cast<int, float>::value));
64STATIC_ASSERT((!has_static_cast<X, Y>::value));
65STATIC_ASSERT((has_static_cast<Z, X>::value));
66
67STATIC_ASSERT(!(has_dynamic_cast<int, float>::value));
68STATIC_ASSERT(!(has_dynamic_cast<X, Y>::value));
69STATIC_ASSERT(!(has_dynamic_cast<X, Z>::value));
70STATIC_ASSERT(!(has_dynamic_cast<Y, Z>::value));
71STATIC_ASSERT((has_dynamic_cast<X*, Z*>::value));
72STATIC_ASSERT((has_dynamic_cast<X*, Y*>::value));
73STATIC_ASSERT(!(has_dynamic_cast<Y*, Z*>::value));
74
75STATIC_ASSERT(!(has_const_cast<int, float>::value));
76STATIC_ASSERT((has_const_cast<const int*, int*>::value));
77STATIC_ASSERT((has_const_cast<int*, const int*>::value));
78STATIC_ASSERT(!(has_const_cast<const int*, float*>::value));
79
80STATIC_ASSERT((has_reinterpret_cast<int*, float*>::value));
81STATIC_ASSERT(!(has_reinterpret_cast<void*, char>::value));
82STATIC_ASSERT(!(has_reinterpret_cast<const X, X>::value));
83
84STATIC_ASSERT((has_c_cast<int, float>::value));
85STATIC_ASSERT(!(has_c_cast<X, Y>::value));
86STATIC_ASSERT(!(has_c_cast<void*, char>::value));
87