Derive Dune::Exception from std::exception.

dune/common/exceptions.hh

@@ -4,6 +4,7 @@
 #ifndef DUNE_EXCEPTIONS_HH
 #define DUNE_EXCEPTIONS_HH
 
+#include <exception>
 #include <string>
 #include <sstream>
 
@@ -88,11 +89,13 @@ namespace Dune {
      \see DUNE_THROW, IOError, MathError
 
    */
-  class Exception {
+  class Exception
+  : public std::exception
+  {
   public:
     Exception ();
     void message(const std::string &msg); //!< store string in internal message buffer
-    const std::string& what() const;        //!< output internal message buffer
+    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
   private:
@@ -196,9 +199,9 @@ namespace Dune {
     _message = msg;
   }
 
-  inline const std::string& Exception::what() const
+  inline const char* Exception::what() const noexcept
   {
-    return _message;
+    return _message.data();
   }
 
   inline std::ostream& operator<<(std::ostream &stream, const Exception &e)