[libc++] Implements concept default_initializable.
Implements:
- LWG3149 DefaultConstructible should require default initialization
Implements parts of:
- P0898R3 Standard Library Concepts
- P1754 Rename concepts to standard_case for C++20, while we still can
Depends on D91986
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D93461
GitOrigin-RevId: 3ffc53ba16272b6475ff49c05ab6aa72f7720383
diff --git a/include/concepts b/include/concepts
index 86e0325..e245e54 100644
--- a/include/concepts
+++ b/include/concepts
@@ -167,6 +167,16 @@
concept constructible_from =
destructible<_Tp> && _VSTD::is_constructible_v<_Tp, _Args...>;
+// [concept.default.init]
+
+template<class _Tp>
+concept __default_initializable = requires { ::new _Tp; };
+
+template<class _Tp>
+concept default_initializable = constructible_from<_Tp> &&
+ requires { _Tp{}; } && __default_initializable<_Tp>;
+
+
#endif //_LIBCPP_STD_VER > 17 && defined(__cpp_concepts) && __cpp_concepts >= 201811L
_LIBCPP_END_NAMESPACE_STD