[Bug fortran/57530] New: [OOP] Wrongly rejects type_pointer => class_target (which have identical declared type)

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57530

            Bug ID: 57530
           Summary: [OOP] Wrongly rejects  type_pointer => class_target
                    (which have identical declared type)
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: janus at gcc dot gnu.org

Found in the examples to http://www.cambridge.org/rouson (->
ssdSource/chapter05/hermetic). According to comments, the original program is
accepted by xlf2003 and nagf95.

The following simplified code is accepted by Crayftn, ifort and pgf95, but
rejected by gfortran with:

    ptr => tgt  ! TYPE => CLASS
    1
Error: Different types in pointer assignment at (1); attempted assignment of
CLASS(t) to TYPE(t)


>From F2008:

"C714 (R733) If data-target is not unlimited polymorphic, data-pointer-object
shall be type compatible (4.3.1.3) with it and the corresponding kind type
parameters shall be equal."

There (4.3.1.3): "A nonpolymorphic entity is type compatible only with entities
of the same declared type. A polymorphic entity that is not an unlimited
polymorphic entity is type compatible with entities of the same declared type
or any of its extensions."


In the example below, TYPE(t) and CLASS(t) have same declared type.


module m
  type t
  end type t
contains
  subroutine sub (tgt)
    class(t), target :: tgt
    type(t), pointer :: ptr
    ptr => tgt  ! TYPE => CLASS
  end subroutine sub
end module m