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From: "matthew.hambley at metoffice dot gov.uk" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/111477] New: Procedure as actual argument fails against
 procedure pointer dummy argument
Date: Tue, 19 Sep 2023 13:15:06 +0000
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X-Bugzilla-Version: 13.2.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111477

            Bug ID: 111477
           Summary: Procedure as actual argument fails against procedure
                    pointer dummy argument
           Product: gcc
           Version: 13.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: matthew.hambley at metoffice dot gov.uk
  Target Milestone: ---

Test case:

> program test
>=20
>   implicit none
>=20
>   abstract interface
>     subroutine one_if()
>       implicit none
>     end subroutine one_if
>   end interface
>=20
>   procedure(one_if), pointer :: one_ptr =3D> null()
>=20
>   call one_proc( first )
>   one_ptr =3D> first
>   call one_proc( one_ptr )
>=20
> contains
>=20
>   subroutine first()
>     implicit none
>   end subroutine first
>=20
>   subroutine one_proc( one )
>=20
>     implicit none
>=20
>     procedure(one_if), pointer, intent(in) :: one
>=20
>     call one()
>=20
>   end subroutine one_proc
>=20
> end program test

This fails to compile the call to "one_proc( first )" but succeedes on the =
call
to "one_proc( one_ptr )".

Consulting with BS ISO/IEC 1539-1:2010 section 12.5.2.9 "Actual arguments
associated with dummy procedure entities", paragraph 5 says:

"If a dummy argument is a procedure pointer, the corresponding actual argum=
ent
shall be a procedure pointer, a reference to a function that returns a
procedure pointer, a reference to the intrinsic function NULL, or a valid
target for the dummy pointer in a pointer assignment statement."

It seems like a procedure with the correct calling signature should be "a v=
alid
target for the dummy pointer" and so it seems like both call forms should w=
ork.

Maybe someone has a more recent version of the standard which clarifies thi=
s or
maybe I've misunderstood the very dense standard-speak.

For reference both Intel and IBM Fortrans do accept both call forms shown
above.=