LI75784: FORTRAN POINTER DEALLOCATION ERROR

November 2010 Update for XL Fortran for Linux, V13.1
April 2011 Update for XL Fortran for Linux, V13.1
July 2011 Update for XL Fortran for Linux, V13.1
October 2011 Update for XL Fortran for Linux, V13.1
June 2012 Update for XL Fortran for Linux, V13.1
October 2012 Update for XL Fortran for Linux, V13.1
XL Fortran for Linux Fix Pack 8 (June 2013 Update) for 13.1

APAR status

• Closed as program error.

Error description

• A deallocation error is encountered during the following
  situation:
  
  From a Fortran routine, data is allocated. c_loc is used to get
  a C-pointer to point to that data, which is passed to the
  C-layer. That C-pointer is passed back to a second Fortran
  routine. The deallocation of this second Fortran pointer is what
  causes this error to occur.
  
       write(0,*) "zz=",zz
       cptr = c_loc(zz)
  !
  !   pass cptr to C-layer
  !
  ! ----------8<----------8<----------
  !
  ! subroutine fortran2(cptr)
  !
       call c_f_pointer(cptr, xy)
     ! xy => zz
       write(0,*) "xy=",xy
  
  So zz is a local Fortran pointer in the first routine, and xy is
  another local Fortran pointer in the second routine.
  
  
  ===== Test Case:
  
    program c_ptr_test
    use iso_c_binding
    implicit none
    type(c_ptr) :: cptr
    real*8, pointer :: zz, xy
      write(0,*) 'Allocate zz'
      allocate(zz)
      zz=5.d0
      write(0,*) "zz=",zz
      cptr = c_loc(zz)
      call c_f_pointer(cptr, xy)
    ! xy => zz
      write(0,*) "xy=",xy
      write(0,*) "Deallocate xy"
      deallocate(xy)
    end program c_ptr_test
  
  ==============================
  
  
  When this test case is compiled using XL Fortran V13.1 on AIX,
  the following message is observed.
  
  
  $ xlf90 c_ptr_test.f90
  $ ./a.out
   Allocate zz
   zz= 5.00000000000000000
   xy= 5.00000000000000000
   Deallocate xy
  "c_ptr_test.f90", line 15: 1525-109 Error encountered while
  attempting to deallocate a data object.  The program will stop.
  $
  

Local fix

• N/A.
  

Problem summary

• PROBLEM DESCRIPTION:
  Information about the permissibility of passing a pointer to
  deallocate is lost after passing the pointer through C_PTR.
  
  USERS AFFECTED:
  Fortran users passing c_ptr pointers through bind(c) and back
  into a fortran pointer.
  

Problem conclusion

• Several workarounds were identified for this situation, but it
  is best to address this issue in your source. if this is not an
  option, please contact IBM support for a workaround that
  switches the default behaviour of c_ptr.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IZ84114

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XL FORTRAN LINU

• Fixed component ID

  5724X1600

Applicable component levels

• RD10 PSY

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