how can I throw error with file and linenumber?

Question

I try to use BOOST_THROW_EXCEPTION to do this, here is example:

#include <boost/throw_exception.hpp>
#include <stdexcept>
void demo_boost_throw()
{
    BOOST_THROW_EXCEPTION(std::runtime_error("boost throw std exception."));
    }
int main() {
    demo_boost_throw();
    return 0;
}

From here we can see it does contain the file

#define BOOST_THROW_EXCEPTION(x)\
        ::boost::throw_exception( ::boost::enable_error_info(x) <<\
        ::boost::throw_function(BOOST_THROW_EXCEPTION_CURRENT_FUNCTION) <<\
        ::boost::throw_file(__FILE__) <<\
        ::boost::throw_line((int)__LINE__) )

But when I run the program, it does not print out the file and line.

There is current_exception_diagnostic_information(), but this require to catch and print. I do not want to catch it. I want the e.what() contain the extra info of throw_function, throw_file and throw_line. How can I do this?

Answer 1

If you, by any chance, have access to C++20, you can easily use std::source_location in a following manner:

#include <string>
#include <sstream>
#include <iostream>
#include <experimental/source_location>

void throw_exception(std::string const& message,
                     std::experimental::source_location const& location = std::experimental::source_location::current()) {
    std::stringstream ss;
    ss << location.file_name()
       << ":"
       << location.line()
       << " "
       << message;
    throw std::runtime_error(ss.str());
}

int main() {
    throw_exception("Random exception");
    return 0;
}

Demo