Module calling an external procedure with implicit interface

Question

The following code, combining module procedures and external procedures:

module module_dummy

  implicit none

contains

           


        

Answer 1

Dummy arguments that are assumed shape must have an explicit interface at their point of reference. F90 12.3.1.1 item 2c.

Practically, assumed shape arrays are passed by passing a descriptor - a little structure that describes the bounds and the location of storage of the array. Ye-olde F77 explicit shape and assumed size arrays are passed simply by passing the address of the first element. Without the explicit interface the compiler doesn't know that it needs to build and pass the descriptor - hence chaos and confusion results.