message: das.named: fix compatibility with newest compilers
diff: @@ -107,7 +107,19 @@ namespace elle
  using type = typename T::Default;
  using Super = typename T::Formal::
  template Effective<typename T::Default, typename T::Default const&>;
  - using Super::Super;
  +
  + // A simple `using Super::Super` does not work with the newest
  + // compilers, stricter than their predecessors even in C++14.
  + //
  + // GCC7: "an inherited constructor is not a candidate for
  + // initialization from an expression of the same or derived
  + // type".
  + //
  + // Clang4: "candidate template ignored: inherited constructor
  + // cannot be used to move object".
  + DefaultFor(Super&& s)
  + : Super{std::move(s)}
  + {}
  };
  template <typename ... Formal>
  