@@ -523,6 +523,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ };
/// is_array
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_array)
+ template<typename _Tp>
+ struct is_array
+ : public __bool_constant<__is_array(_Tp)>
+ { };
+#else
template<typename>
struct is_array
: public false_type { };
@@ -534,6 +540,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
struct is_array<_Tp[]>
: public true_type { };
+#endif
template<typename>
struct __is_pointer_helper
@@ -3183,12 +3190,17 @@ template <typename _Tp>
template <typename _Tp>
inline constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_array)
+template <typename _Tp>
+ inline constexpr bool is_array_v = __is_array(_Tp);
+#else
template <typename _Tp>
inline constexpr bool is_array_v = false;
template <typename _Tp>
inline constexpr bool is_array_v<_Tp[]> = true;
template <typename _Tp, size_t _Num>
inline constexpr bool is_array_v<_Tp[_Num]> = true;
+#endif
template <typename _Tp>
inline constexpr bool is_pointer_v = is_pointer<_Tp>::value;
This patch optimizes the performance of the is_array trait by dispatching to the new __is_array built-in trait. libstdc++-v3/ChangeLog: * include/std/type_traits (is_array): Use __is_array built-in trait. (is_array_v): Likewise. Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org> --- libstdc++-v3/include/std/type_traits | 12 ++++++++++++ 1 file changed, 12 insertions(+)