typo. made the what() method in the code-snippet const declared.

[SVN r25161]

more/error_handling.html

@@ -75,8 +75,8 @@
 
 <pre>
 #include &lt;iostream&gt;
-struct my_exc1 : std::exception { char const* what() throw(); };
-struct my_exc2 : std::exception { char const* what() throw(); };
+struct my_exc1 : std::exception { char const* what() const throw(); };
+struct my_exc2 : std::exception { char const* what() const throw(); };
 struct your_exc3 : my_exc1, my_exc2 {};
 
 int main()