libstdc++: Add __cpp_lib_unwrap_ref feature test macro

[gcc.git] / libstdc++-v3 / include / std / type_traits

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 684a792d02c19d284b58d6e33149ed93bb090b92..14aa2b37a4f113e60e91c559a00b8ab3d2cfc39f 100644 (file)
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3242,6 +3242,8 @@ template <typename _From, typename _To>
   template<typename _Tp>
     using type_identity_t = typename type_identity<_Tp>::type;
 
+#define __cpp_lib_unwrap_ref 201811L
+
   /// Unwrap a reference_wrapper
   template<typename _Tp>
     struct unwrap_reference { using type = _Tp; };