Fix compiler error in move constructor

trie.hpp

@@ -58,7 +58,7 @@ private:
 public:
   trie() {}
   trie(trie const & other);
-  trie(trie && other) { swap(other); }
+  trie(trie && other) : trie() { swap(*this, other); }
   ~trie() { clear(); }
   self_t & operator=(mapped_type const & value);
   self_t & operator=(trie const & value);