DPL: drop need for has_root_setowner

Simple inline constrain is much better.

Author: ktf

Framework/Core/include/Framework/DataRefUtils.h

@@ -122,7 +122,7 @@ struct DataRefUtils {
         // object only depends on the state at serialization of the original object. However,
         // all objects created during deserialization are new and must be owned by the collection
         // to avoid memory leak. So we call SetOwner if it is available for the type.
-        if constexpr (has_root_setowner<T>::value) {
+        if constexpr (requires(T t) { t.SetOwner(true); }) {
           result->SetOwner(true);
         }
       });
@@ -159,7 +159,7 @@ struct DataRefUtils {
           throw runtime_error_f("Unable to extract class %s", cl == nullptr ? "<name not available>" : cl->GetName());
         }
         // workaround for ROOT feature, see above
-        if constexpr (has_root_setowner<T>::value) {
+        if constexpr (requires(T t) { t.SetOwner(true); }) {
           result->SetOwner(true);
         }
       });

Framework/Core/include/Framework/TypeTraits.h

@@ -147,22 +147,5 @@ class has_root_dictionary<T, typename std::enable_if<is_container<T>::value>::ty
 {
 };
 
-// Detect whether a class is a ROOT class implementing SetOwner
-// This member detector idiom is implemented using SFINAE idiom to look for
-// a 'SetOwner()' method.
-template <typename T, typename _ = void>
-struct has_root_setowner : std::false_type {
-};
-
-template <typename T>
-struct has_root_setowner<
-  T,
-  std::conditional_t<
-    false,
-    class_member_checker<
-      decltype(std::declval<T>().SetOwner(true))>,
-    void>> : public std::true_type {
-};
-
 } // namespace o2::framework
 #endif // FRAMEWORK_TYPETRAITS_H