Implicit length character array and bind(c) subroutine

We recently updated to IFORT 15.0.2.179. A few of the regression tests for our code system now fail. The basic pattern is calling a function written in C with a slice of a two-dimensional character array; the compiler is not passing a pointer to the correct word in the character array. Here is a reduced example; we declare an interface to the C routine and iterate over the rows of a character array, passing the first column to the C function:

module r
  interface
     subroutine cprint ( leng, chars ) bind (c)
       use, intrinsic :: iso_c_binding, only : c_int, c_char
       integer(kind=c_int) :: leng
       character(kind=c_char,len=1) :: chars( leng )
     end subroutine cprint
  end interface
end module r

subroutine b ( leng, chars )
  use r
  integer :: leng, i
  character(len=*) :: chars( leng, 2 )
  do i = 1, 2
     call cprint( leng, chars(:,i) )
  end do
end subroutine b

program a
  integer, parameter :: leng = 23
  integer :: i
  character(len=1) :: chars( leng, 2 )
  character(len=leng) :: buffer
  buffer = 'ABCDEFGHIJ'
  do i = 1, leng
     chars(i,1) = buffer(i:i)
  end do
  buffer = '1234567890'
  do i = 1, leng
     chars(i,2) = buffer(i:i)
  end do
  call b( leng, chars )
end program a

and the C++ subroutine:

#include <cstdio>
extern "C" void cprint ( const int* leng, const char* chars )
{
  for ( int i = 0; i < *leng; ++i ) {
    putc( chars[i], stdout );
  }
  putc( '\n', stdout );
  fflush( stdout );
}

I expect this to print:

ABCDEFGHIJ
1234567890

But instead I get:

ABCDEFGHIJ
ABCDEFGHIJ

If I look at the assembly code for subroutine b, it appears that the correct address for chars(:,i) is not being computed; it just uses the same address for each iteration.

Variations: If I replace character(len=*) with character(len=1) in subroutine b, the correct strings are printed by cprint. If I leave in (len=*) but call a Fortran print subroutine with the same arguments, the correct strings are printed.

I tried my example program with ifort 14.0.4.237 and it also prints the incorrect strings. But, our main program, which is lot larger, works correctly. Kind of odd.

Thanks,
Allen