using std::swap before swap calls

alib2std/src/extensions/forward_tree.hpp

@@ -518,6 +518,8 @@ public:
 // ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 	friend void swap ( forward_tree & first, forward_tree & second ) {
+		using std::swap;
+
 		swap ( std::move ( first.m_data ), std::move ( second.m_data ) );
 		swap ( std::move ( first.m_children ), std::move ( second.m_children ) );
 	}

alib2std/src/extensions/tree.hpp

@@ -553,6 +553,8 @@ public:
 // ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 	friend void swap ( tree & first, tree & second ) {
+		using std::swap;
+
 		swap ( std::move ( first.m_data ), std::move ( second.m_data ) );
 		swap ( std::move ( first.m_children ), std::move ( second.m_children ) );
 		swap ( std::move ( first.m_parent ), std::move ( second.m_parent ) );

alib2std/src/extensions/tree_base.hpp

@@ -113,7 +113,9 @@ public:
 	}
 	AnyaryNode & operator =( AnyaryNode && other ) noexcept {
-		std::swap ( this->children_union.children, other.children_union.children );
+		using std::swap;
+
+		swap ( this->children_union.children, other.children_union.children );
 		setParent ( std::make_index_sequence < arity > ( ) );
@@ -302,7 +304,9 @@ public:
 	}
 	FixedaryNode & operator =( FixedaryNode && other ) noexcept {
-		std::swap ( this->children_union.children, other.children_union.children );
+		using std::swap;
+
+		swap ( this->children_union.children, other.children_union.children );
 		for ( Data & child : children_union.children )
 			child->parent = static_cast < Cast * > ( this );
@@ -378,7 +382,9 @@ public:
 	}
 	VararyNode & operator =( VararyNode && other ) noexcept {
-		std::swap ( this->children_union.children, other.children_union.children );
+		using std::swap;
+
+		swap ( this->children_union.children, other.children_union.children );
 		for ( Data & child : children_union.children )
 			child->parent = static_cast < Cast * > ( this );

alib2std/src/extensions/utility.hpp

@@ -65,7 +65,9 @@ struct rvalue_ref {
 	rvalue_ref & operator = ( const rvalue_ref & ) = delete;
 	rvalue_ref & operator = ( rvalue_ref && other ) {
-		std::swap(holder, other.holder);
+		using std::swap;
+
+		swap(holder, other.holder);
 	}
 	~rvalue_ref ( ) {

alib2std/src/extensions/variant.hpp

@@ -240,8 +240,10 @@ public:
 	// move assignment operator
 	variant<Ts...>& operator= (variant<Ts...> && old) noexcept {
-		std::swap(this->type_id, old.type_id);
-		std::swap(this->data, old.data);
+		using std::swap;
+
+		swap(this->type_id, old.type_id);
+		swap(this->data, old.data);
 		return *this;
 	}