[Bug fortran/64944] New: Coarrays not registered for structure constructor with allocatable coarray components

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64944

            Bug ID: 64944
           Summary: Coarrays not registered for structure constructor with
                    allocatable coarray components
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: pault at gcc dot gnu.org

Follow up to PR64757 and https://gcc.gnu.org/ml/fortran/2015-02/msg00022.html

"[...] I wonder whether we need to take care of:

type m
  integer :: i
end type m
type t
  CLASS(m), allocatable :: caf[:]
end type t
type(t), save :: x = t(m())
end

"We probably do. I think that's valid as it is (kind of) statically allocated.
That means we need to call for -fcoarray=lib the _gfortran_caf_register
function for x%caf as constructor (in the C sense) - such that the address is
registered at program start up. The (pointer) assignment of that address to
x%caf can be done later, e.g. when the procedure (or __MAIN) is actually
entered."


Thinking about it, I wonder what happens if one uses:

call foo(t(m()))
contains
subroutine foo(y)
  type(t) :: y
end subroutine foo

In that case, one surely doesn't want to allocate a coarray on all images.


And finally, the following probably works fine - but it has to continue to do
so:

  type(t) :: y
  y = t(m())

in that case, the RHS shall not allocate a coarray - but just do assign to the
LHS. The rules of intrinsic assignment require that the user ensures that y%caf
has the same allocation status and shape/type as on the RHS.