Function catch

extern/boost/boost/system/detail/error_code.hpp:284–288

            }
#if !defined(BOOST_NO_EXCEPTIONS)
            catch( ... )
            {
                detail::snprintf( buffer, len, "No message text available for error std:%s:%d", ec.category().name(), ec.value() );
                return buffer;
            }
#endif
        }
#endif