Add missing virtual destructor

src/util/symbol_table_base.cpp

@@ -5,6 +5,12 @@
 #include <ostream>
 #include <algorithm>
 
+/// Destructor
+symbol_table_baset::~symbol_table_baset()
+{
+}
+
+
 /// Add a new symbol to the symbol table
 /// \param symbol: The symbol to be added to the symbol table
 /// \return Returns true if the process failed, which should only happen if

src/util/symbol_table_base.h

@@ -42,6 +42,8 @@ class symbol_table_baset
   symbol_table_baset(const symbol_table_baset &other) = delete;
   symbol_table_baset &operator=(const symbol_table_baset &other) = delete;
 
+  virtual ~symbol_table_baset();
+
 public:
   /// Permits implicit cast to const symbol_tablet &
   operator const symbol_tablet &() const