[Bug fortran/47180] New: [OOP] EXTENDS_TYPE_OF returns the wrong result if the polymorphic variable is unallocated

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47180

           Summary: [OOP] EXTENDS_TYPE_OF  returns the wrong result if the
                    polymorphic variable is unallocated
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org
                CC: janus@gcc.gnu.org


Found when looking at PR 41580.

The following program should print 6 times "T" but it prints trice "F" followed
by trice "T".

>From Fortran 2008:
"13.7.60 EXTENDS_TYPE_OF (A, MOLD)"

"Result Value.  [unlimited polymorphic] ; otherwise if the dynamic type of A or
MOLD is extensible, the result is true if and only if the dynamic type of A is
an extension type of the dynamic type of MOLD; otherwise the result is
processor dependent."

"NOTE 13.12  The dynamic type of a disassociated pointer or unallocated
allocatable variable is its declared type."


(NAG 5.1 ICEs and ifort prints the same result as gfortran; nevertheless, I
expect that the code is correct, which is in line with NOTE 13.12.)


implicit none
type t1
  integer :: a
end type t1
type, extends(t1):: t11
  integer :: b
end type t11

type(t1) a1
type(t11) a11
class(t1), allocatable :: b1
class(t11), allocatable :: b11

print *, extends_type_of(b1,a1)   ! T - currently, gfortran prints "F"
print *, extends_type_of(b11,a1)  ! T - currently, gfortran prints "F"
print *, extends_type_of(b11,a11) ! T - currently, gfortran prints "F"

allocate(t1 :: b1)
allocate(t11 :: b11)

print *, extends_type_of(b1,a1)   ! T
print *, extends_type_of(b11,a1)  ! T
print *, extends_type_of(b11,a11) ! T
end