[libc++][chrono] Add sys_time formatter.
Partially implements:
- P1361 Integration of chrono with text formatting
- P2372 Fixing locale handling in chrono formatters
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D144739
diff --git a/libcxx/include/__chrono/concepts.h b/libcxx/include/__chrono/concepts.h
index 38d6b0c..61ec256 100644
--- a/libcxx/include/__chrono/concepts.h
+++ b/libcxx/include/__chrono/concepts.h
@@ -11,6 +11,7 @@
#define _LIBCPP___CHRONO_CONCEPTS_H
#include <__chrono/hh_mm_ss.h>
+#include <__chrono/time_point.h>
#include <__config>
#include <__type_traits/is_specialization.h>
@@ -25,6 +26,9 @@
template <class _Tp>
concept __is_hh_mm_ss = __is_specialization_v<_Tp, chrono::hh_mm_ss>;
+template <class _Tp>
+concept __is_time_point = __is_specialization_v<_Tp, chrono::time_point>;
+
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
