Call-graph ramifications of the FORD type-bound procedures public/private policy

[patflynngithub]

The FORD type-bound procedures public/private policy (discussed a bit here in issue #508) has ramifications for call-graph display of type-bound procedures.

First some example code:

program main
  
  use a_module
  implicit none
  
  type(a_module_t)  :: a_module_t_obj
  call a_module_t_obj%a_module_t_sub("There")

end program main
! ---------------------------
module a_module

implicit none
private

public :: a_module_t
! public :: a_module_t_sub  ! THIS IS THE STATEMENT THAT ALLOWS THE TYPE-BOUND PROCEDURE
                            !  TO BE DISPLAYED IN THE CALL-GRAPH

  type a_module_t
    private
    integer :: a_module_t_int
  contains
    procedure :: a_module_t_sub
  end type a_module_t

contains

subroutine a_module_t_sub(this, output)
    implicit none
    
    class(a_module_t), intent(in) :: this
    character(len=*), intent(in)  :: output   !! character(len=*), intent(in) :: output

     write(*,*) "a_module_t_sub: ", output
 end subroutine a_module_t_sub

end module a_module

When graphs are generated for this code, the publicly accessible type-bound procedure a_module_t_sub() is not displayed in the main program's call graph. In fact, because the program only has the type-bound procedure call, no call-graph is generated at all for the program. If there were other procedure calls in the program that FORD considers "fully" public, then the call-graph would be generated (minus the non fully public type-bound procedure).

The solution to this is the same as getting the type-bound procedures to be listed on the FORD Procedures main page list and the Procedures webpage. Add

public :: a_module_t_sub

at the module level of a_module (commented in above code).

So, as with the display of type-bound procedures in the FORD Procedures list and webpage, we are forced to modify our Fortran code just to get FORD to document it in a way that it seems FORD should be able do without the code change.

[patflynngithub]

@ZedThree
A further wrinkle in this issue is when there is a binding name (i.e. sub in this case) added to the type-bound procedure from the above orginal code example:

  type a_module_t
    private
    integer :: a_module_t_int
  contains
    procedure :: sub => a_module_t_sub
  end type a_module_t

along with a main program call to the binding name

call a_module_t_obj%sub("There")

Regardless if there is a public :: a_module_t_sub statement and there is no module-level private statement, this call does not appear in the program's call-graph (the call-graph is not even generated in this case because it's the only procedure call).

[ZedThree]

This is at least partially fixed in #539. "Called-by" graphs are not yet generated for type-bound procedures, I will look into fixing that when I have time.