[Bug fortran/98903] New: [Coarray, F2018] Implement TEAM_NUMBER in image-selector-spec

["tkoenig at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98903

            Bug ID: 98903
           Summary: [Coarray, F2018] Implement TEAM_NUMBER in
                    image-selector-spec
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tkoenig at gcc dot gnu.org
  Target Milestone: ---

The following is currently rejected:

program main
  use, intrinsic :: iso_fortran_env
  type (team_type) :: odd_even
  integer :: me, my_team, n
  integer :: i
  integer :: a[*]
  me = this_image()
  n = num_images()
  a = me*100
  my_team = 2-mod(this_image(), 2)
  form team (my_team, odd_even)
  change team (odd_even)
  if (me == 1) then
     do i=1,n
        print *,a[i,team_number=-1]
     end do
  end if
  end team
end program main

$ gfortran -fcoarray=lib ft2.f90
ft2.f90:15:32:

   15 |         print *,a[i,team_number=-1]
      |                                1
Error: Invalid form of coarray reference at (1)

According to 9.6, R926, this is valid.

(-1 is the team number for the initial team, see

3.145.4 team number
−1 which identifies the initial team, or positive integer that identifies a
team within its parent team

)