A question about coarrays and -Warray-temporaries

[Jorge D'Elia <jdelia@intec.unl.edu.ar>]

Hi all,

I have a question with -Warray-temporaries in the test below. 

With the AA coarray that warning appears in the first loop (on its local part), 
but not with the BB array with the same task, i.e.


$ gfortran --version
GNU Fortran (GCC) 11.0.0 20210125 (experimental)
Copyright (C) 2021 Free Software Foundation, Inc.

$ gfortran -march=native -mtune=native -Ofast -fcheck=all -fcoarray=single -std=f2018 -Wall -Wextra -Warray-temporaries -o test.exe test.f90 
test.f90:37:19:

   37 |     AA (k1:nn,j) = AA (k1:nn,j) - UU (k1:nn) * AA (k,j)
      |                   1
Warning: Creating array temporary at (1) [-Warray-temporaries]


Why this difference in behavior? Is it ok? 

Thanks in advance for some clarification. 

Greetings. 
Jorge

program test
  implicit none
  integer, parameter :: iin = kind (1)     
  integer, parameter :: idp = kind (1.0d0) 
  real    (kind=idp), allocatable :: AA (:,:)[:]
  real    (kind=idp), allocatable :: BB (:,:)
  real    (kind=idp), allocatable :: UU (:)
  integer (kind=iin) :: nn, n1, n2
  integer (kind=iin) :: j, k, k1
  !
  nn =  5
  n1 =  1
  n2 = 10
  !
  allocate (AA (1:nn,n1:n2)[*])
  allocate (BB (1:nn,n1:n2))
  allocate (UU (1:nn))
  !
  k  = 1
  k1 = k + 1
  !
  AA = 1.0_idp
  UU = 2.0_idp
  !
  do  j = 1, nn
    AA (k1:nn,j) = AA (k1:nn,j) - UU (k1:nn) * AA (k,j)
  end do
  !
  do  j = 1, nn
    BB (k1:nn,j) = BB (k1:nn,j) - UU (k1:nn) * BB (k,j)
  end do
  !
  deallocate (AA)
  deallocate (BB)
  deallocate (UU)
  !
end program test
--