Currenlty, ifx/ifort cannot compile the given executable as it is not
valid Fortran. It is missing the external keyword on the
no_arg_subroutine. Gfortran compiles the example but this is actually
a bug and there is an open gcc ticket for this here:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50377
Adding the keyword does not change the gfortran compiling of the example.
It will, however, prevent a future fail once 50377 has been addressed.
type(cart_nd) :: c_nd
type(nested_cart_3d) :: nested_c
character(40) :: returned_string, returned_string_debugger
+ external no_arg_subroutine
real8 = 3.00
real4 = 9.3
integer_array = 17