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Implement LWG 2770 - Make tuple_size<T> defined for all T

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git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@286779 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Fiselier
2016-11-13 20:43:50 +00:00
parent fc044a1ff2
commit f9a20c2c38
5 changed files with 32 additions and 6 deletions
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2
include/__tuple
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@@ -22,7 +22,7 @@
_LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY tuple_size; template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY tuple_size {};
template <class _Tp> template <class _Tp>
class _LIBCPP_TYPE_VIS_ONLY tuple_size<const _Tp> class _LIBCPP_TYPE_VIS_ONLY tuple_size<const _Tp>

2
include/tuple
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@@ -84,7 +84,7 @@ template <class T, class Tuple>
constexpr T make_from_tuple(Tuple&& t); // C++17 constexpr T make_from_tuple(Tuple&& t); // C++17
// 20.4.1.4, tuple helper classes: // 20.4.1.4, tuple helper classes:
template <class T> class tuple_size; // undefined template <class T> class tuple_size;
template <class... T> class tuple_size<tuple<T...>>; template <class... T> class tuple_size<tuple<T...>>;
template <class T> template <class T>
constexpr size_t tuple_size_v = tuple_size<T>::value; // C++17 constexpr size_t tuple_size_v = tuple_size<T>::value; // C++17

6
test/std/utilities/tuple/tuple.tuple/tuple.helper/tuple_size.fail.cpp
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@@ -21,7 +21,7 @@
int main() int main()
{ {
(void)std::tuple_size<std::tuple<> &>::value; // expected-error {{implicit instantiation of undefined template}} (void)std::tuple_size<std::tuple<> &>::value; // expected-error {{no member named 'value'}}
(void)std::tuple_size<int>::value; // expected-error {{implicit instantiation of undefined template}} (void)std::tuple_size<int>::value; // expected-error {{no member named 'value'}}
(void)std::tuple_size<std::tuple<>*>::value; // expected-error {{implicit instantiation of undefined template}} (void)std::tuple_size<std::tuple<>*>::value; // expected-error {{no member named 'value'}}
} }

26
test/std/utilities/tuple/tuple.tuple/tuple.helper/tuple_size.pass.cpp
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@@ -18,19 +18,36 @@
// UNSUPPORTED: c++98, c++03 // UNSUPPORTED: c++98, c++03
#include <tuple> #include <tuple>
#include <utility>
#include <array>
#include <type_traits> #include <type_traits>
template <class T, class = decltype(std::tuple_size<T>::value)>
constexpr bool has_value(int) { return true; }
template <class> constexpr bool has_value(long) { return false; }
template <class T> constexpr bool has_value() { return has_value<T>(0); }
template <class T, std::size_t N> template <class T, std::size_t N>
void test() void test()
{ {
static_assert(has_value<T>(), "");
static_assert((std::is_base_of<std::integral_constant<std::size_t, N>, static_assert((std::is_base_of<std::integral_constant<std::size_t, N>,
std::tuple_size<T> >::value), ""); std::tuple_size<T> >::value), "");
static_assert(has_value<const T>(), "");
static_assert((std::is_base_of<std::integral_constant<std::size_t, N>, static_assert((std::is_base_of<std::integral_constant<std::size_t, N>,
std::tuple_size<const T> >::value), ""); std::tuple_size<const T> >::value), "");
static_assert(has_value<volatile T>(), "");
static_assert((std::is_base_of<std::integral_constant<std::size_t, N>, static_assert((std::is_base_of<std::integral_constant<std::size_t, N>,
std::tuple_size<volatile T> >::value), ""); std::tuple_size<volatile T> >::value), "");
static_assert(has_value<const volatile T>(), "");
static_assert((std::is_base_of<std::integral_constant<std::size_t, N>, static_assert((std::is_base_of<std::integral_constant<std::size_t, N>,
std::tuple_size<const volatile T> >::value), ""); std::tuple_size<const volatile T> >::value), "");
{
static_assert(!has_value<T &>(), "");
static_assert(!has_value<T *>(), "");
}
} }
int main() int main()
@@ -39,4 +56,13 @@ int main()
test<std::tuple<int>, 1>(); test<std::tuple<int>, 1>();
test<std::tuple<char, int>, 2>(); test<std::tuple<char, int>, 2>();
test<std::tuple<char, char*, int>, 3>(); test<std::tuple<char, char*, int>, 3>();
test<std::pair<int, void*>, 2>();
test<std::array<int, 42>, 42>();
{
static_assert(!has_value<void>(), "");
static_assert(!has_value<void*>(), "");
static_assert(!has_value<int>(), "");
static_assert(!has_value<std::pair<int, int>*>(), "");
static_assert(!has_value<std::array<int, 42>&>(), "");
}
} }

2
test/std/utilities/tuple/tuple.tuple/tuple.helper/tuple_size_v.fail.cpp
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@@ -22,5 +22,5 @@ int main()
(void)std::tuple_size_v<std::tuple<> &>; // expected-note {{requested here}} (void)std::tuple_size_v<std::tuple<> &>; // expected-note {{requested here}}
(void)std::tuple_size_v<int>; // expected-note {{requested here}} (void)std::tuple_size_v<int>; // expected-note {{requested here}}
(void)std::tuple_size_v<std::tuple<>*>; // expected-note {{requested here}} (void)std::tuple_size_v<std::tuple<>*>; // expected-note {{requested here}}
// expected-error@tuple:* 3 {{implicit instantiation of undefined template}} // expected-error@tuple:* 3 {{no member named 'value'}}
} }