RANDOM_INIT() and coarray Fortran

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

What to do about RANDOM_INIT() and coarray Fortran?

The main issue is that if one compiles with -fcoarray=lib
(or the WIP -fcoarray=shared), then RANDOM_INIT() may
require communication between images.  Thus, RANDOM_INIT()
cannot live in libgfortran for at least -fcoarray=lib.

Consider the simple code:

subroutine foo
   call random_init(.true., .false.)
end subroutine foo

I have updated the patch for
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98301
to use a stub routine for -fcoarray=lib and -fcoarray=shared.
Anyone, who knows how to use git, is encouraged to commit the patch.

For -fcoarray=none (default option) and -fcoarray=single, the
patch will cause gfortran to generate

__attribute__((fn spec (". ")))
void foo ()
{
  _gfortran_random_init (1, 0, 0);
}

_gfortran_random_init() live in libgfortran and it has been updated
to meet the intended requires of the Fortran standard.

With -fcoarray=lib and -fcoarray=shared, gfortran will now generate

__attribute__((fn spec (". ")))
void foo ()
{
  _gfortran_random_init_foobar (1, 0);
}

where _gfortran_random_init_foobar() lives in libgfortran.  It prints
an error message that RANDOM_INIT() is not yet supported for coarray
Fortran and exits.  Someone, who cares about coarray Fortran, can fix
-fcoarray=lib and -fcoarray=shared by updating trans-decl.c (see the
FIXME for random_init()) to emit 

__attribute__((fn spec (". ")))
void foo ()
{
  _gfortran_caf_random_init (1, 0);
}

or

__attribute__((fn spec (". ")))
void foo ()
{
  _gfortran_cas_random_init (1, 0);
}

-- 
Steve