[Bug fortran/54784] New: [oop] allocation of extended types with polymorphic allocatable members

["jkozdon at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54784

             Bug #: 54784
           Summary: [oop] allocation of extended types with polymorphic
                    allocatable members
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jkozdon@gmail.com


(Error also occurs with gcc 4.7.1)

When I have a container module with stores a collection of polymorphics types,
I sometimes get an error that a pointer is being freed which was not allocated. 

An example program is below. It can be compiled without errors
   gfortran bug.f90

It contains four modules each with an associated type. If the type 'block' in
'block_module' the member nFields is commented out the code runs fine.

If a print statement is added in the program the code runs fine

If the dimension of the member 'x' of types block_cart1d and block_cart2d are
changed so that they are not 3 and 4 (only one must be changed), the program
works.

Finally, if the order in the program of the addBlock command is reversed the 

bug.f90
--------
module block_module
  implicit none
  private

  public :: block
  type,abstract :: block
    ! if commented out code works fine
    integer       ,private :: nFields      = 0
  end type block

end module block_module

module block1d_module
  use block_module, only : block

  type,extends(block) :: block1d
    real,dimension(:,:,:),allocatable,private :: fields
  end type
end module

module block2d_module
  use block_module, only : block

  type,extends(block) :: block2d
    real,dimension(:,:,:,:),allocatable,private :: fields
  end type
end module


module domain_module
  use block_module, only : block

  implicit none
  type :: list
    class(block),allocatable :: B
  end type

  type :: domain
    type(list),dimension(10) :: L
  contains
    procedure :: addBlock
  end type
contains

  subroutine addBlock(this,i,b)
    implicit none
    class(domain),intent(inout) :: this
    integer,intent(in) :: i
    class(block),intent(in) :: b

    allocate(this%L(i)%B,source=b)
  end subroutine
end module

program bug
  use domain_module, only : domain
  use block1d_module, only : block1d
  use block2d_module, only : block2d
  implicit none
  type(domain) :: d
  type(block1d) :: b1
  type(block2d) :: b2

  ! crashes with "pointer being freed was not allocated"
  call d%addBlock(1,b1)
  call d%addBlock(2,b2)

  ! crashes with "invalid memory reference"
  ! call d%addBlock(2,b2)
  ! call d%addBlock(1,b1)

  ! runs fine
  ! call d%addBlock(1,b2)
  ! call d%addBlock(2,b1)

end program  bug