https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113338
Bug ID: 113338
Summary: Valid Code Rejected, bind(C) procedure with pointer
argument
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: everythingfunctional at protonmail dot com
Target Milestone: ---
The following example is rejected by gfortran, but should be valid.
Fortran Program:
program example
use iso_c_binding
implicit none
type :: t
integer :: i
end type
interface
subroutine c_proc(x) bind(c)
import t
implicit none
type(t), pointer, intent(in) :: x
end subroutine
end interface
type(t), target :: x
x%i = 42
call c_proc(x)
contains
subroutine f_proc(x) bind(c)
type(t), pointer, intent(in) :: x
print *, x%i
end subroutine
end program
C code:
#include <ISO_Fortran_binding.h>
extern void f_proc(CFI_cdesc_t* x);
extern void c_proc(CFI_cdesc_t* x)
{
f_proc(x);
}
Is rejected with the following messages:
main.f90:11:27:
11 | subroutine c_proc(x) bind(c)
| 1
Error: Variable ‘x’ at (1) is a dummy argument to the BIND(C) procedure
‘c_proc’ but is not C interoperable because derived type ‘t’ is not C
interoperable
main.f90:23:23:
23 | subroutine f_proc(x) bind(c)
| 1
Error: Variable ‘x’ at (1) is a dummy argument to the BIND(C) procedure
‘f_proc’ but is not C interoperable because derived type ‘t’ is not C
interoperable
But the standard says:
> A Fortran procedure interface is interoperable with a C function prototype if
> ...
> (5) any dummy argument without the VALUE attribute corresponds to a formal
> parameter of the prototype that is of a pointer type, and either
> ...
> * the dummy argument is allocatable, assumed-shape, assumed-rank, or a
> pointer without the CONTIGUOUS attribute, and the formal parameter is a
> pointer to CFI_cdesc_t
I.e., that argument need not be interoperable, because it has the pointer
attribute.
