LI76065: NON STANDARD PROG COMPILES W/O (L) MSG

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

• The first of the two programs below do not conform to the
  Fortran Standard.
  
  The issue is that the user should have an explicit interface
  for the 'binary_search' function because it has an assumed-
  shape array argument. The compiler passes extra hidden
  arguments and/or descriptors for assumed-shape arrays, and
  thus it needs to do that on the caller side.
  
  Inaddition, the standard says that the interface of a function
  is explicit within the function if the function has the
  result() clause, otherwise, it is not explicit. So a result
  clause should be reported as missing by the compiler.
  
  However there is no "L" warning messages when compiling with
  -qlanglvl set with conformance with standard Fortran 90, 95 or
  2003.
  
  ========== Test case 1
  (This should cause the compiler to produce a message during
  compilation)
  
   recursive function binary_search(field,what)
    integer, dimension(:),intent(in) :: field
    integer, intent (in) :: what
    integer :: binary_search
    integer :: n,mid
    n=size(field)
    if (n==0) then
     binary_search = 0
     return
    end if
    mid = n/2 + 1
    if (field(mid)>what) then
     binary_search = binary_search(field(1:mid-1),what)
    else if (field(mid)<what) then
     binary_search = binary_search(field(mid+1:n),what)
     if (binary_search /= 0 ) binary_search = binary_search + mid
    else ! field(mid)==what)
     binary_search = mid
    end if
   end function binary_search
  
  
  ========== Test case 2
  (This is the correct version of the program)
  
   recursive function binary_search(field,what) result(found)
    integer, dimension(:),intent(in) :: field
    integer, intent (in) :: what
    integer :: found
    integer :: n,mid
    n=size(field)
    if (n==0) then
     found = 0
     return
    end if
    mid = n/2 + 1
    if (field(mid)>what) then
     found = binary_search(field(1:mid-1),what)
    else if (field(mid)<what) then
     found = binary_search(field(mid+1:n),what)
     if (found /= 0 ) found = found + mid
    else ! field(mid)==what)
     found = mid
    end if
   end function binary_search
  

Local fix

• N/A
  

Problem summary

• PROBLEM DESCRIPTION:
  A recursive function containing a self reference must have a
  result value specified in the declaration of the function, by
  the Fortran standard. We do not flag this as with a language
  level message and allow non-standard Fortran programs.
  
  USERS AFFECTED:
  Anyone making use of the -qlanglvl option.
  

Problem conclusion

• An appropriate language level message will now be generated,
  flagging the non-conforming semantics. A recursive function
  without a result value containing a self reference will cause
  the message to be generated.
  

Temporary fix

Comments

APAR Information

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

  IZ86161

• 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 PSN IZ86161

     UP06/09/13