Re: why diagnostic_information is std::exception::what: Unknown exception

From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2023-10-30 03:16:53

Can't repro on godbolt/gcc: https://godbolt.org/z/rWddT5xce.

I know you're using MSVC but please provide compiler version and Boost
version.

On Sun, Oct 29, 2023 at 7:29 AM Bernard via Boost-users <
boost-users_at_[hidden]> wrote:

> greetings kind regards
> may i please inquire how not to obtain "std::exception::what: Unknown
> exception" from diagnosic_inforumation() . my meaning is to inquire how to
> obtain as per example on boost web page
> https://www.boost.org/doc/libs/1_83_0/libs/exception/doc/tutorial_diagnostic_information.html
> output : "std::exception::what: example_io error"
> id est where did "example_io error" come from as neither boost::exception
> nor std:::exception accept constructor string arguments .
>
>  please my code below .
> thank you kindly
>
> #include "stl" // #includes all stl #include files
> #include "boost\exception\all.hpp"
> using namespace std;
>
> struct ceXception : virtual boost::exception, virtual std::exception
> {
> using this_type = ceXception;
> ceXception() {}
> auto what() { cerr << __FUNCSIG__ << endl; return string("return from " +
> string(__FUNCSIG__)); }
> template<typename charType>
> friend
> std::basic_ostream<charType>& operator<<(std::basic_ostream<charType>&
> _ostream, const this_type&) { cerr << "to cerr from " << __FUNCSIG__ <<
> endl; _ostream << "to ostream from " << __FUNCSIG__ << endl; return
> _ostream; }
> };
>
> void foo()
> {
> try { BOOST_THROW_EXCEPTION(ceXception()); }
> catch (ceXception& e)
> {
> cerr << boost::diagnostic_information(e);
> }
> }
>
> int main()
> {
> foo();
> return 0;
> }
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