feedc0de/mp-units
1
0
Fork 0
forked from mpusz/mp-units
Code Pull Requests Activity

fix: downcasting facility for non-default-constructible types

Browse Source
This commit is contained in:
Johel Ernesto Guerrero Peña
2021-02-17 15:51:39 +01:00
committed by Mateusz Pusz
parent 02ea4825e8
commit 052d818385
2 changed files with 4 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/include/units/bits/external/downcasting.h
Vendored
+3 -3
View File
@@ -56,7 +56,7 @@ concept has_downcast_poison_pill = requires(T t) { downcast_poison_pill(t); };
template<typename Target, Downcastable T>
struct downcast_child : T {
friend auto downcast_guide(typename T::downcast_base)
{ return Target(); }
{ return std::type_identity<Target>(); }
};
template<Downcastable T>
@@ -89,13 +89,13 @@ constexpr auto downcast_impl()
if constexpr(has_downcast_guide<T> && !has_downcast_poison_pill<T>)
return decltype(downcast_guide(std::declval<downcast_base<T>>()))();
else
return T();
return std::type_identity<T>();
}
} // namespace detail
template<Downcastable T>
using downcast = decltype(detail::downcast_impl<T>());
using downcast = TYPENAME decltype(detail::downcast_impl<T>())::type;
template<Downcastable T>
using downcast_base_t = TYPENAME T::downcast_base_type;