J3/10-184
To: J3
From: Malcolm Cohen
Subject: Final interp 8: ELEMENTAL INTENT(OUT)
Date: 2010 June 13

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NUMBER:
TITLE: ELEMENTAL INTENT(OUT) finalization
KEYWORDS: PURE INTENT(OUT) FINAL
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTION:

Consider
  MODULE m
    TYPE t1
      REAL,POINTER :: vec(:)
    CONTAINS
      FINAL f1
    END TYPE
    TYPE t2
      REAL,POINTER :: vec(:)
    CONTAINS
      FINAL f2
    END TYPE
  CONTAINS
    PURE SUBROUTINE f1(x)
      TYPE(t1),INTENT(INOUT) :: x
      IF (ASSOCIATED(x%f1)) DEALLOCATE(x%f1)
    END SUBROUTINE
    PURE SUBROUTINE f2(y)
      TYPE(t1),INTENT(INOUT) :: y(:)
      INTEGER i
      DO i=1,SIZE(y)
        IF (ASSOCIATED(y(i)%f1)) DEALLOCATE(y(i)%f1)
      END DO
    END SUBROUTINE
    ELEMENTAL SUBROUTINE zap1(z1)
      TYPE(t1),INTENT(OUT) :: z1
    END SUBROUTINE
    ELEMENTAL SUBROUTINE zap2(z2)
      TYPE(t2),INTENT(OUT) :: z2
    END SUBROUTINE
  END MODULE
  ...
  TYPE(t1) a,aa(10)
  TYPE(t2) b,bb(10)
  ...
  CALL zap1(a)    ! (1)
  CALL zap1(aa)   ! (2)
  CALL zap2(b)    ! (3)
  CALL zap2(bb)   ! (4)

The question is which CALL statements result in finalization and thus
deallocation of the various vec components.

If the finalization of an INTENT(OUT) argument is considered to happen
"on invocation" in the caller, then presumably the CALL statements
marked (1) and (4) will result in deallocation.

On the other hand, if the finalization of an INTENT(OUT) argument is
considered to be done in the called procedure, then arguably it is the
CALL statements marked (1) and (2) instead that will result in
deallocation.

In either case some clarification would seem to be useful.

Q. Which statements result in deallocation of the vec components?

Note that this interacts with another interp request.

ANSWER:

A. The finalization is considered to occur in the context of the
   caller, so the statements marked (1) and (4) will result in
   deallocation of the vec components.

ALTERNATIVE ANSWER:

A. The finalization is considered to occur in the called procedure,
   so the statements marked (1) and (2) will result in deallocation of
   the vec components.

EDITS to 10-007:

[76:31] At the end of 4.5.6.3 paragraph 8, append new sentence
  "The finalization caused by INTENT(OUT) is considered to occur in
   the context of the invocation of the procedure, not within the
   invoked procedure."
{This edit is identical to the first edit possibility in the other
 interp request.}

ALTERNATIVE EDITS:

[76:31] At the end of 4.5.6.3 paragraph 8, append new sentence
  "The finalization caused by INTENT(OUT) is considered to occur
   within the invoked procedure; so for elemental procedures, an
   INTENT(OUT) argument will be finalized only if a scalar or
   elemental final subroutine is available, regardless of the rank
   of the actual argument."
{This edit is additional to the second edit possibility in the other
 interp request.}

SUBMITTED BY: Malcolm Cohen

HISTORY: 10-184   m192 Submitted

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