diff --git a/include/sqlpp11/core/aggregate_function/enable_over.h b/include/sqlpp11/core/aggregate_function/enable_over.h
index 37724d7f..9864fbc9 100644
--- a/include/sqlpp11/core/aggregate_function/enable_over.h
+++ b/include/sqlpp11/core/aggregate_function/enable_over.h
@@ -47,7 +47,6 @@ namespace sqlpp
     }
   };
 
-#warning: Need to use in tests
   template <typename T>
   struct has_enabled_over : public std::is_base_of<enable_over<T>, T>
   {
diff --git a/include/sqlpp11/core/basic/enable_join.h b/include/sqlpp11/core/basic/enable_join.h
index eb8adfea..60a86f6a 100644
--- a/include/sqlpp11/core/basic/enable_join.h
+++ b/include/sqlpp11/core/basic/enable_join.h
@@ -41,41 +41,40 @@ namespace sqlpp
 
   public:
     template <typename T>
-    auto join(T t) const -> decltype(::sqlpp::join(this->derived(), t))
+    auto join(T t) const -> decltype(::sqlpp::join(this->derived(), std::move(t)))
     {
-#warning: move?
-      return ::sqlpp::join(this->derived(), t);
+      return ::sqlpp::join(this->derived(), std::move(t));
     }
 
     template <typename T>
-    auto inner_join(T t) const -> decltype(::sqlpp::inner_join(this->derived(), t))
+    auto inner_join(T t) const -> decltype(::sqlpp::inner_join(this->derived(), std::move(t)))
     {
-      return ::sqlpp::inner_join(this->derived(), t);
+      return ::sqlpp::inner_join(this->derived(), std::move(t));
     }
 
     template <typename T>
-    auto left_outer_join(T t) const -> decltype(::sqlpp::left_outer_join(this->derived(), t))
+    auto left_outer_join(T t) const -> decltype(::sqlpp::left_outer_join(this->derived(), std::move(t)))
     {
-      return ::sqlpp::left_outer_join(this->derived(), t);
+      return ::sqlpp::left_outer_join(this->derived(), std::move(t));
     }
 
     template <typename T>
-    auto right_outer_join(T t) const -> decltype(::sqlpp::right_outer_join(this->derived(), t))
+    auto right_outer_join(T t) const -> decltype(::sqlpp::right_outer_join(this->derived(), std::move(t)))
     {
-      return ::sqlpp::right_outer_join(this->derived(), t);
+      return ::sqlpp::right_outer_join(this->derived(), std::move(t));
     }
 
 #warning: There is no full_outer_join in mysql?
     template <typename T>
-    auto full_outer_join(T t) const -> decltype(::sqlpp::full_outer_join(this->derived(), t))
+    auto full_outer_join(T t) const -> decltype(::sqlpp::full_outer_join(this->derived(), std::move(t)))
     {
-      return ::sqlpp::full_outer_join(this->derived(), t);
+      return ::sqlpp::full_outer_join(this->derived(), std::move(t));
     }
 
     template <typename T>
-    auto cross_join(T t) const -> decltype(::sqlpp::cross_join(this->derived(), t))
+    auto cross_join(T t) const -> decltype(::sqlpp::cross_join(this->derived(), std::move(t)))
     {
-      return ::sqlpp::cross_join(this->derived(), t);
+      return ::sqlpp::cross_join(this->derived(), std::move(t));
     }
   };
 }  // namespace sqlpp
diff --git a/include/sqlpp11/core/clause/delete_from.h b/include/sqlpp11/core/clause/delete_from.h
index 97145268..59b54f1f 100644
--- a/include/sqlpp11/core/clause/delete_from.h
+++ b/include/sqlpp11/core/clause/delete_from.h
@@ -41,11 +41,6 @@ namespace sqlpp
   };
   struct delete_t : public statement_name_t<delete_name_t>
   {
-    using _traits = make_traits<no_value_t>;
-    struct _sqlpp_name_tag
-    {
-    };
-
     template <typename Statement>
     struct _result_methods_t
     {
diff --git a/include/sqlpp11/core/clause/insert.h b/include/sqlpp11/core/clause/insert.h
index b51db566..f87fdd3e 100644
--- a/include/sqlpp11/core/clause/insert.h
+++ b/include/sqlpp11/core/clause/insert.h
@@ -43,11 +43,6 @@ namespace sqlpp
 
   struct insert_t : public statement_name_t<insert_name_t>
   {
-    using _traits = make_traits<no_value_t>;
-    struct _sqlpp_name_tag
-    {
-    };
-
     template <typename Statement>
     struct _result_methods_t
     {
diff --git a/include/sqlpp11/core/clause/into.h b/include/sqlpp11/core/clause/into.h
index 37b10a95..f8065b87 100644
--- a/include/sqlpp11/core/clause/into.h
+++ b/include/sqlpp11/core/clause/into.h
@@ -55,14 +55,8 @@ namespace sqlpp
   template <typename Table>
   struct into_t
   {
-    using _traits = make_traits<no_value_t, tag::is_into>;
-
     using _data_t = into_data_t<Table>;
 
-    struct _sqlpp_name_tag
-    {
-    };
-
     // Base template to be inherited by the statement
     template <typename Policies>
     struct _base_t
diff --git a/include/sqlpp11/core/clause/select_column_list.h b/include/sqlpp11/core/clause/select_column_list.h
index a504d916..75da89ec 100644
--- a/include/sqlpp11/core/clause/select_column_list.h
+++ b/include/sqlpp11/core/clause/select_column_list.h
@@ -253,10 +253,6 @@ namespace sqlpp
   {
     using _traits = make_traits<no_value_t, tag::is_noop, tag::is_missing>;
 
-    struct _sqlpp_name_tag
-    {
-    };
-
     using _data_t = no_data_t;
 
     // Base template to be inherited by the statement
diff --git a/include/sqlpp11/core/clause/single_table.h b/include/sqlpp11/core/clause/single_table.h
index 8891107a..58616194 100644
--- a/include/sqlpp11/core/clause/single_table.h
+++ b/include/sqlpp11/core/clause/single_table.h
@@ -54,18 +54,12 @@ namespace sqlpp
   template <typename Table>
   struct single_table_t
   {
-    using _traits = make_traits<no_value_t, tag::is_single_table>;
-
-#warning: can't we do this with a table_t<> specialization
+#warning: can't we do this with a table_t<> specialization?
     static_assert(is_table<Table>::value, "argument has to be a table");
     static_assert(required_tables_of_t<Table>::empty(), "table depends on another table");
 
     using _data_t = single_table_data_t<Table>;
 
-    struct _sqlpp_name_tag
-    {
-    };
-
     // Base template to be inherited by the statement
     template <typename Policies>
     struct _base_t
diff --git a/include/sqlpp11/core/clause/update.h b/include/sqlpp11/core/clause/update.h
index f6841f46..c653f410 100644
--- a/include/sqlpp11/core/clause/update.h
+++ b/include/sqlpp11/core/clause/update.h
@@ -43,11 +43,6 @@ namespace sqlpp
 
   struct update_t : public statement_name_t<update_name_t>
   {
-    using _traits = make_traits<no_value_t>;
-    struct _sqlpp_name_tag
-    {
-    };
-
     template <typename Statement>
     struct _result_methods_t
     {
diff --git a/include/sqlpp11/core/database/parameter_list.h b/include/sqlpp11/core/database/parameter_list.h
index 78ddb22a..559a0df9 100644
--- a/include/sqlpp11/core/database/parameter_list.h
+++ b/include/sqlpp11/core/database/parameter_list.h
@@ -64,7 +64,6 @@ namespace sqlpp
     }
   };
 
-#warning: Why would we need this?
   template <typename Exp>
   using make_parameter_list_t = parameter_list_t<parameters_of_t<Exp>>;
 }  // namespace sqlpp
diff --git a/include/sqlpp11/core/group_by_column.h b/include/sqlpp11/core/group_by_column.h
index b3aea711..0ab3de6c 100644
--- a/include/sqlpp11/core/group_by_column.h
+++ b/include/sqlpp11/core/group_by_column.h
@@ -71,7 +71,6 @@ namespace sqlpp
   template <typename Context, typename Expr>
   auto to_sql_string(Context& context, const group_by_column<Expr>& t) -> std::string
   {
-#warning: Untested
     return to_sql_string(context, t._expr);
   }
 
@@ -84,7 +83,5 @@ template <typename Expr, typename = check_declare_group_by_column_args<Expr>>
     return {std::move(expr)};
   }
 
-#warning Add tests
-
 }  // namespace sqlpp11
 
diff --git a/include/sqlpp11/core/noop.h b/include/sqlpp11/core/noop.h
index 455c1d62..2395755e 100644
--- a/include/sqlpp11/core/noop.h
+++ b/include/sqlpp11/core/noop.h
@@ -35,13 +35,6 @@ namespace sqlpp
   struct noop
   {
 #warning: All this should go away
-    using _traits = make_traits<no_value_t, tag::is_noop>;
-    using _nodes = detail::type_vector<>;
-
-    struct _sqlpp_name_tag
-    {
-    };
-
     template <typename Statement>
     struct _result_methods_t
     {
diff --git a/include/sqlpp11/core/type_traits/group_by_column.h b/include/sqlpp11/core/type_traits/group_by_column.h
index 2bd57542..91d619bc 100644
--- a/include/sqlpp11/core/type_traits/group_by_column.h
+++ b/include/sqlpp11/core/type_traits/group_by_column.h
@@ -40,7 +40,5 @@ namespace sqlpp
   {
   };
 
-#warning Add tests
-
 }  // namespace sqlpp11
 
diff --git a/include/sqlpp11/postgresql/returning_column_list.h b/include/sqlpp11/postgresql/returning_column_list.h
index b3c0cf13..87a93e97 100644
--- a/include/sqlpp11/postgresql/returning_column_list.h
+++ b/include/sqlpp11/postgresql/returning_column_list.h
@@ -218,11 +218,6 @@ namespace sqlpp
     struct no_returning_column_list_t
     {
       using _traits = make_traits<no_value_t, tag::is_noop, tag::is_missing>;
-      using _nodes = ::sqlpp::detail::type_vector<>;
-
-      struct _sqlpp_name_tag
-      {
-      };
 
       // Data
       using _data_t = no_data_t;
diff --git a/include/sqlpp11/sqlite3/insert_or.h b/include/sqlpp11/sqlite3/insert_or.h
index e632ae48..31774bde 100644
--- a/include/sqlpp11/sqlite3/insert_or.h
+++ b/include/sqlpp11/sqlite3/insert_or.h
@@ -49,11 +49,6 @@ namespace sqlpp
     template <typename InsertOrAlternative>
     struct insert_or_t : public statement_name_t<InsertOrAlternative>
     {
-      using _traits = make_traits<no_value_t>;
-      struct _sqlpp_name_tag
-      {
-      };
-
       template <typename Statement>
       struct _result_methods_t
       {
diff --git a/tests/core/types/clause/group_by.cpp b/tests/core/types/clause/group_by.cpp
index 4d8ed5e1..f97a3081 100644
--- a/tests/core/types/clause/group_by.cpp
+++ b/tests/core/types/clause/group_by.cpp
@@ -40,6 +40,9 @@ void test_group_by()
   auto col_int = test::TabFoo{}.id;
   auto col_txt = test::TabFoo{}.textNnD;
 
+  // Test that declared group by columns are considered group by columns
+  static_assert(sqlpp::is_group_by_column<decltype(declare_group_by_column(v))>::value, "");
+
   // Constant values are neutral and therefore considered neither aggregate and non-aggregate.
   static_assert(decltype(known_aggregate_columns_as_expected(col_int))::value, "");
   static_assert(decltype(known_aggregate_columns_as_expected(col_int, col_txt))::value, "");