include/denc: use concept to define denc_traits

to be more specific, define denc_traits for types with ext types

Signed-off-by: Kefu Chai <tchaikov@gmail.com>

diff --git a/src/include/denc.h b/src/include/denc.h
index 92224252a52a1ddd8f64f132dd78cc831316fd69..621da9e70bcc29b081f0880353ec967fbe317595 100644 (file)
--- a/src/include/denc.h
+++ b/src/include/denc.h
@@ -376,7 +376,8 @@ using ExtType_t = typename ExtType<T>::type;
 } // namespace _denc
 
 template<typename T>
-struct denc_traits<T, std::enable_if_t<!std::is_void_v<_denc::ExtType_t<T>>>>
+requires (!std::is_void_v<_denc::ExtType_t<T>>)
+struct denc_traits<T>
 {
   static constexpr bool supported = true;
   static constexpr bool featured = false;