2017-06-05  Nicolas Koenig  <koenigni@student.ethz.ch>

	PR fortran/35339
	* frontend-passes.c (traverse_io_block): New function.
	(simplify_io_impl_do): New function.
	(optimize_namespace): Invoke gfc_code_walker with
	simplify_io_impl_do.

2017-06-05  Nicolas Koenig  <koenigni@student.ethz.ch>

	PR fortran/35339
	* gfortran.dg/implied_do_io_1.f90: New Test.
	* gfortran.dg/implied_do_io_2.f90: New Test.

From-SVN: r248877