re PR libstdc++/40296 ([C++0x] std::exception_ptr comparisons)

2010-06-06  Jonathan Wakely  <jwakely.gcc@gmail.com>

	PR libstdc++/40296
	* libsupc++/exception_ptr.h (exception_ptr::exception_ptr): Replace
	__safe_bool constructor with nullptr_t constructor in C++0x mode.
	(exception_ptr::operator bool): Add explicit conversion to bool.
	(swap(exception_ptr&, exception_ptr&)): Add.
	(exception_ptr::_M_safe_bool_dummy): Only declare for old ABI.
	* libsupc++/eh_ptr.cc (exception_ptr::_M_safe_bool_dummy): Move
	next to other functions retained for ABI compatibility.
	* testsuite/18_support/exception_ptr/requirements.cc: New.
	* testsuite/18_support/exception_ptr/requirements_neg.cc: New.

From-SVN: r160340