To: J3                                                     J3/23-220
From: John Reid & Reinhold Bader
Subject: Interp for MOVE_ALLOC with FROM a coarray
Date: 2023-October-02

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NUMBER: F23/xxx
TITLE: MOVE_ALLOC with FROM a coarray
KEYWORDS: MOVE_ALLOC, coarray
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress
REFERENCES: 23-007r1

QUESTION:
Was it intended that if FROM is a coarray, all images of the team be
required to have corresponding coarrays?

For example, in the following program the subroutine is executed on all
images and the coarray s is allocated on all images and is moved to
coarray t on all images. However, the coarrays on images 1 to ne/2 do
not correspond to the coarrays on images ne/2+1 to ne and therefore cannot
be accessed from each other. Was this intended?

program trouble
  real, allocatable :: a[:], b[:]
  integer :: me, ne
  allocate(a[*],b[*])
  a = 1
  b = 2
  me = this_image()
  ne = num_images()
  if (me>ne/2) then
     call sub (b)
  else
     call sub (a)
  end if
contains
  subroutine sub(s)
     real, allocatable :: s[:], t[:]
     integer :: i
     if (me==1 .or. me==ne) write(*,*) "On image",me," s=",s
     call move_alloc (s,t)
     if (me==1 .or. me==ne) write(*,*) "On image",me," t=",t
  end subroutine
end program

ANSWER:
No, these effects were not intended. An edit is supplied to require
that if FROM is a coarray all images of the current team have
corresponding coarrays.

EDIT to 23-007r1:

[422:23] In 16.9.147 MOVE_ALLOC, at the end of the para labelled FROM,
add
"If it is a coarray, all images of the current team shall have
corresponding coarrays."

SUBMITTED BY: John Reid & Reinhold Bader

HISTORY: 23-170   m230  Submitted