2012-07-03  Paolo Carlini  <paolo.carlini@oracle.com>

	PR libstdc++/53840
	* include/std/ratio (ratio_multiply, ratio_divide, ratio_add,
	ratio_subtract): Use template aliases.
	* include/std/chrono (duration<>::duration(const duration<>&),
	duration_cast): Adjust.
	* testsuite/20_util/ratio/operations/53840.cc: New.
	* testsuite/20_util/duration/requirements/typedefs_neg1.cc: Adjust.
	* testsuite/20_util/duration/requirements/typedefs_neg2.cc: Likewise.
	* testsuite/20_util/duration/requirements/typedefs_neg3.cc: Likewise.
	* testsuite/20_util/ratio/operations/ops_overflow_neg.cc: Likewise.

From-SVN: r189239