Revert "auto_base: flatten the list of base classes"

This reverts commit f96f531.

Author: tomjnixon

include/adm/detail/auto_base.hpp

@@ -32,7 +32,7 @@ namespace adm {
     /// make a class derived from the given base classes, combining the
     /// get, set, has, isDefault and unset overloads
     template <typename... Bases>
-    using HasParameters = HasParametersImpl<TypeList<Bases...>>;
+    using HasParameters = Combine<TypeList<Bases...>>;
 
     /// Get the default value of T parameters. Specialise this to add custom
     /// defaults.

include/adm/detail/auto_base_detail.hpp

@@ -101,53 +101,5 @@ namespace adm {
       using AddRemoveBases::add...;
       using AddRemoveBases::remove...;
     };
-
-    /// flatten a TypeList of classes; any Combine<TypeList<B...>, ...> in
-    /// FlattenBases is replaced by B...
-    ///
-    /// This is used to deal with VariantParameter, which is implemented with
-    /// HasParameters (and therefore Combine). This works, but makes for
-    /// excessively long type names, and more classes than necessary
-    template <typename Bases>
-    struct FlattenBases;
-
-    // turn Combine at the head into its TypeList of bases
-    template <typename HeadBases, typename... HeadArgs, typename... Tail>
-    struct FlattenBases<TypeList<Combine<HeadBases, HeadArgs...>, Tail...>> {
-      using type =
-          typename FlattenBases<Cons<HeadBases, TypeList<Tail...>>>::type;
-    };
-
-    // handle the head of a TypeList at the head
-    template <typename HeadHead, typename... HeadTail, typename... Tail>
-    struct FlattenBases<TypeList<TypeList<HeadHead, HeadTail...>, Tail...>> {
-      using type =
-          Cons<HeadHead, typename FlattenBases<Cons<TypeList<HeadTail...>,
-                                                    TypeList<Tail...>>>::type>;
-    };
-
-    // handle an empty TypeList at the head
-    template <typename... Tail>
-    struct FlattenBases<TypeList<TypeList<>, Tail...>> {
-      using type = typename FlattenBases<TypeList<Tail...>>::type;
-    };
-
-    // handle a regular base at the head
-    template <typename Head, typename... Tail>
-    struct FlattenBases<TypeList<Head, Tail...>> {
-      using type = Cons<Head, typename FlattenBases<TypeList<Tail...>>::type>;
-    };
-
-    // handle an empty list
-    template <>
-    struct FlattenBases<TypeList<>> {
-      using type = TypeList<>;
-    };
-
-    /// implementation for HasParameters, accepting a TypeList of bases and
-    /// yielding a Combine with the appropriate classes in each list, selected
-    /// by flags
-    template <typename BasesList>
-    using HasParametersImpl = Combine<typename FlattenBases<BasesList>::type>;
   }  // namespace detail
 }  // namespace adm