std::uncaught_exception flag not reset properly

[haukeduden]

When an exception is re-thrown and re-caught inside a catch handler then the std::uncaught_exception flag remains set indefinitely. This is a bug, as there is not actually an uncaught active exception at that point.

This is a problem for some unittest frameworks (like the Catch framework), which re-throw exceptions that occur during a test to determine the exception type. This bug is a showstopper for using these frameworks.

I have tested this with version 1.36.5 (current "incoming" branch).

The following code reproduces the bug:

#include <iostream>
#include <exception>

int main()
{   
    try
    {       
        throw std::exception();
    }
    catch(std::exception)
    {
        try
        {
            throw;
        }
        catch(std::exception)
        {

        }
    }

    if(std::uncaught_exception())
        std::cout << "ERROR: uncaught_exception still set.";
    else
        std::cout << "OK";

   return 0;

}

[kripken]

Thanks, looks like in that pattern begin_catch is called more than once on a single exception, which we didn't expect. Fixed on incoming and added this to the test suite.