[Bug fortran/46991] New: [OOP] polymorphic assumed-size actual arguments

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46991

           Summary: [OOP] polymorphic assumed-size actual arguments
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org
                CC: janus@gcc.gnu.org


Found at http://j3-fortran.org/pipermail/j3/2010-December/004084.html

Currently, it is unclear whether the following program is valid, but Robert
Corbett of Oracle (formerly Sun) thinks it is (but does not seem to like it.)

[100% guessing, 90% wrongly]: The main issue he sees is seemingly that SUB2
does not need to have an explicit interface - which only works if the $data of
a CLASS and a TYPE object start at the same offset of the passed pointer
address.

I think that part is OK in gfortran, but gfortran has other issues:


Gfortran rejects the program with:

        CALL SUB2(A, N)
                  1
Warning: Type mismatch in argument 'a' at (1); passed CLASS(rec) to TYPE(rec)

[That's PR 46990.] I also tried SELECT TYPE but with limited success.


Using
        CLASS(REC) A(*)
one gets:
        PRINT *, A(:N)%A
                   1
Error: Syntax error in argument list at (1)


 * * *

       MODULE TYPES
         PRIVATE
         PUBLIC REC, REC2

         TYPE REC
           INTEGER A
         END TYPE

         TYPE, EXTENDS(REC) :: REC2
           INTEGER B
         END TYPE
       END

       SUBROUTINE SUB1(A, N)
         USE TYPES
         CLASS(REC), INTENT(IN) :: A(*)

         CALL SUB2(A, N)
       END

       SUBROUTINE SUB2(A, N)
         USE TYPES
         TYPE(REC) A(*)

         PRINT *, A(:N)%A
       END

       PROGRAM MAIN
         USE TYPES
         CLASS(REC), ALLOCATABLE :: A(:)
         INTERFACE
           SUBROUTINE SUB1(A, N)
             USE TYPES
             CLASS(REC), INTENT(IN) :: A(*)
           END SUBROUTINE
         END INTERFACE

         A = [ (REC2(I, I+1), I = 1, 10) ]
         CALL SUB1(A, 10)
       END