LI75385: ISSUE WITH EXPLICIT SHAPE ARRAYS

May 2010 Update for XL Fortran for Linux, V12.1
January 2012 Update for XL Fortran for Linux, V12.1
January 2011 Update for XL Fortran for Linux, V12.1
June 2011 Update for XL Fortran for Linux, V12.1
XL Fortran for Linux Fix Pack 8 (January 2014 Update) for 12.1

APAR status

• Closed as program error.

Error description

• An assumed shape array is passed to a subroutine and declared as
  an explicit array inside the subroutine.  This leads to
  incorrect results in the content of the passed array.
  
  The test case below displays this behaviour.   Since
  the subroutine, s2, has no interface definition, the array
  argument should be passed as a FORTRAN77 array and explicit/
  assumed array shape should not matter for the results.
  
  
     ======  TESTCASE  ======
  
    type dt
       integer :: idx (4)
    end type
    type(dt), allocatable :: c(:)
  
    allocate (c(3))
  
    c(:)% idx(4) = (/1,2,3/)
    call s1 (c(:)% idx(4))
  
  contains
  
    subroutine s1 (DX)
      integer               :: DX(:)
      if ( any(dx /= (/1,2,3/)) ) stop 10
      call s2 ( DX)
    end subroutine
  
    SUBROUTINE s2 (DATA)
      INTEGER  ,INTENT(IN)  :: DATA(3)    ! Incorrect Output
  !    INTEGER  ,INTENT(IN)  :: DATA(:)    ! Correct Output
  
      print *, "DATA =", data
      if ( any(data /= (/1,2,3/)) ) stop 11
  
    END SUBROUTINE
  
  end
  

Local fix

• To workaround the issue, the declaration of the array in the
  subroutine needs to be changed from assumed shape to explicit
  shape.
  

Problem summary

• USERS AFFECTED:
  Users passing discontiguous dummy-arg arrays by descriptor to
  routines that operate on contiguous arrays by default.
  
  PROBLEM DESCRIPTION:
  The compiler may interpret/output the passed array incorrectly.
  

Problem conclusion

• The compiler was improved to better detect discontiguity.
  

Temporary fix

Comments

APAR Information

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

  IZ65814

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

Fix information

• Fixed component name

  XL FORTRAN RHEL

• Fixed component ID

  5724U8410

Applicable component levels

• RC10 PSN IZ65814

     UP06/09/13