[exception] std::exception::what is virtual

dune/common/exceptions.hh

@@ -95,9 +95,9 @@ namespace Dune {
   public:
     Exception ();
     void message(const std::string &msg); //!< store string in internal message buffer
-    const char* what() const noexcept;        //!< output internal message buffer
+    virtual const char* what() const noexcept; //!< output internal message buffer
     static void registerHook (ExceptionHook * hook); //!< add a functor which is called before a Dune::Exception is emitted (see Dune::ExceptionHook) \see Dune::ExceptionHook
-    static void clearHook ();                       //!< remove all hooks
+    static void clearHook ();                  //!< remove all hooks
   private:
     std::string _message;
     static ExceptionHook * _hook;
@@ -199,7 +199,7 @@ namespace Dune {
     _message = msg;
   }
 
-  inline const char* Exception::what() const noexcept
+  const char* Exception::what() const noexcept
   {
     return _message.data();
   }