Re: [Mingw-users] gcc 3.2 EH mechanism is not perfect

[Cristian A. <ac...@po...>]

Oscar Fuentes wrote:

>Seems the compilers are right:
>
>>From 15.4/8:
>Whenever an exception is thrown and the search for a handler (15.3)
>encounters the outermost block of a function with an
>exception-specification, the function unexpected() is called (15.5.2)
>if the exception-specification does not allow the exception.
>
>>From 15.4/9
>The function unexpected() may throw an exception that will satisfy the
>exception-specificationfor which it was invoked, and in this case the
>search for another handler will continue at the call of the function
>with this exception-specification(see 15.5.2), or it may call
>terminate().
>
>Finally, from 15.5.2/2:
>
>The unexpected() function shall not return, but it can throw (or
>re-throw) an exception. If it throws a new exception which is allowed
>by the exception specification which previously was violated, then the
>search for another handler will continue at the call of the function
>whose exception specification was vio-lated.  If it throws or rethrows
>an exception that the exception-specificationdoes not allow then the
>follow-ing happens: If the exception-specificationdoes not include the
>class std::bad_exception (18.6.2.1) then the function terminate() is
>called, otherwise the thrown exception is replaced by an
>implementation-defined object of the type std::bad_exception and the
>search for another handler will continue at the call of the function
>whose exception-specificationwas violated.
>
>  
>
Thanks for the pointers, now I got it :)
Here is the correct code sample:

#include <exception>
#include <iostream>

void f() throw(int, std::bad_exception)
{
    std::cout << "Throw a char" << std::endl;
    throw '0';
}

void handler()
{
    std::cout << "Handler - retrowing the same char";
    throw;
}

int main()
{
    std::set_unexpected(handler);
    try
    {
        f();
    }
    catch(const std::bad_exception& be)
    {
        std::cout << "Caught a bad_exception" << std::endl;
    }
}

Cheers,
Cristian.