[Bug libstdc++/61643] New: [C++11] std::uncaught_exception returns wrong values after std::rethrow_if_nested

["ai.azuma at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61643

            Bug ID: 61643
           Summary: [C++11] std::uncaught_exception returns wrong values
                    after std::rethrow_if_nested
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ai.azuma at gmail dot com

The following program should terminate successfully.

//=========================================================
#include <stdexcept>
#include <exception>
#include <cstdlib>

struct X
{
  ~X() {
    if (!std::uncaught_exception()) std::abort();    // (A)
  }
};

int main() {
  try {
    throw std::runtime_error("");
  }
  catch (...) {
    try {
      std::throw_with_nested(std::runtime_error(""));
    }
    catch (std::runtime_error const &e) {
      try {
        X x;
        std::rethrow_if_nested(e);
      }
      catch (std::runtime_error const &e) {
        if (std::uncaught_exception()) std::abort(); // (B)
      }
    }
  }
  return EXIT_SUCCESS;
}
//=========================================================

However, the program is aborted at the line marked with `(A)', and at the line
marked with `(B)' if the line marked with `(A)' is commented out.

This problem is reproduced with 4.10.0 20140622, 4.9.1 20140625 and 4.8.4
20140619. The reproducer requires -std=c++11 flag to compile.