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PR libstdc++/79195 fix make_array type deduction

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PR libstdc++/79195
	* include/experimental/array (__make_array_elem): New class template
	and partial specialization.
	(__is_reference_wrapper): Move into __make_array_elem specialization.
	(make_array): Use __make_array_elem to determine element type and move
	static assertion into specialization. Qualify std::forward call.
	(to_array): Add exception specifiation.
	* testsuite/experimental/array/make_array.cc: Test argument types
	without a common type.
	* testsuite/experimental/array/neg.cc: Adjust expected error message.

From-SVN: r244813
This commit is contained in:
Jonathan Wakely 2017-01-23 15:56:05 +00:00 committed by Jonathan Wakely
parent f368600fcd
commit 61ad58f3aa
4 changed files with 51 additions and 23 deletions
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13
libstdc++-v3/ChangeLog
View File

@ -1,3 +1,16 @@
2017-01-23 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/79195
* include/experimental/array (__make_array_elem): New class template
and partial specialization.
(__is_reference_wrapper): Move into __make_array_elem specialization.
(make_array): Use __make_array_elem to determine element type and move
static assertion into specialization. Qualify std::forward call.
(to_array): Add exception specifiation.
* testsuite/experimental/array/make_array.cc: Test argument types
without a common type.
* testsuite/experimental/array/neg.cc: Adjust expected error message.
2017-01-22 Gerald Pfeifer <gerald@pfeifer.com>
* doc/xml/manual/debug.xml: code.google.com uses https now.

46
libstdc++-v3/include/experimental/array
View File

@ -57,35 +57,40 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* @{
*/
template <typename _Up>
struct __is_reference_wrapper : false_type
{};
template<typename _Dest, typename... _Types>
struct __make_array_elem
{
using type = _Dest;
};
template <typename _Up>
struct __is_reference_wrapper<reference_wrapper<_Up>> : true_type
{};
template<typename... _Types>
struct __make_array_elem<void, _Types...>
: common_type<_Types...>
{
template <typename>
struct __is_reference_wrapper : false_type
{};
template <typename _Up>
struct __is_reference_wrapper<reference_wrapper<_Up>> : true_type
{};
static_assert(!__or_<__is_reference_wrapper<decay_t<_Types>>...>::value,
"make_array must be used with an explicit target type when"
"any of the arguments is a reference_wrapper");
};
template <typename _Dest = void, typename... _Types>
constexpr auto
constexpr
array<typename __make_array_elem<_Dest, _Types...>::type, sizeof...(_Types)>
make_array(_Types&&... __t)
-> array<conditional_t<is_void_v<_Dest>,
common_type_t<_Types...>,
_Dest>,
sizeof...(_Types)>
{
static_assert(__or_<
__not_<is_void<_Dest>>,
__and_<__not_<__is_reference_wrapper<decay_t<_Types>>>...>>
::value,
"make_array cannot be used without an explicit target type "
"if any of the types given is a reference_wrapper");
return {{forward<_Types>(__t)...}};
return {{ std::forward<_Types>(__t)... }};
}
template <typename _Tp, size_t _Nm, size_t... _Idx>
constexpr array<remove_cv_t<_Tp>, _Nm>
__to_array(_Tp (&__a)[_Nm],
index_sequence<_Idx...>)
__to_array(_Tp (&__a)[_Nm], index_sequence<_Idx...>)
{
return {{__a[_Idx]...}};
}
@ -93,6 +98,7 @@ template <typename _Tp, size_t _Nm, size_t... _Idx>
template <typename _Tp, size_t _Nm>
constexpr array<remove_cv_t<_Tp>, _Nm>
to_array(_Tp (&__a)[_Nm])
noexcept(is_nothrow_constructible<remove_cv_t<_Tp>, _Tp&>::value)
{
return __to_array(__a, make_index_sequence<_Nm>{});
}

13
libstdc++-v3/testsuite/experimental/array/make_array.cc
View File

@ -18,7 +18,6 @@
// <http://www.gnu.org/licenses/>.
#include <experimental/array>
#include <functional>
struct MoveOnly
{
@ -27,7 +26,7 @@ struct MoveOnly
MoveOnly& operator=(MoveOnly&&) = default;
};
int main()
void test01()
{
char x[42];
std::array<char, 42> y = std::experimental::to_array(x);
@ -45,3 +44,13 @@ int main()
= std::experimental::make_array(1,2L, 3);
constexpr std::array<MoveOnly, 1> zzz2 = std::experimental::make_array(MoveOnly{});
}
void test02()
{
// PR libstdc++/79195
struct A {};
struct B : A {};
struct C : A {};
auto arr = std::experimental::make_array<A>(B{}, C{});
static_assert(std::is_same<decltype(arr), std::array<A, 2>>::value, "");
}

2
libstdc++-v3/testsuite/experimental/array/neg.cc
View File

@ -24,5 +24,5 @@ int main()
{
int dummy;
auto bad = std::experimental::make_array(std::ref(dummy));
// { dg-error "make_array cannot be used without an explicit target type if any of the types given is a reference_wrapper" "" { target *-*-* } 76 }
// { dg-error "explicit target type" "" { target *-*-* } 78 }
}