Equip the visitor macro with a virtual dtor.

diff --git a/ginac/registrar.h b/ginac/registrar.h
index 333b5f070f6ffca2c38429c1f9ab698bf9b0968e..16f39020d9ec1d1b89834077b8a733de4d78687c 100644 (file)
--- a/ginac/registrar.h
+++ b/ginac/registrar.h
@@ -113,6 +113,7 @@ public: \
        class visitor { \
        public: \
                virtual void visit(const classname &) = 0; \
+               virtual ~visitor() {}; \
        };
 
 /** Macro for inclusion in the declaration of each registered class.