gfortran: OpenACC init, set and shutdown directives are not accepted ("Unclassifiable OpenACC directive")

! # Finding (GCC 16.2): gfortran does not accept the OpenACC init, set and shutdown directives; the reproducer is the catalog
!   program acc34-directive-init
!
! - toolchains: gcc_g90 (GCC 16.2.0, AMD Instinct MI250X gfx90a, Tioga) and gcc_sm80 (GCC 16.2.0,
!   NVIDIA A100 sm_80, wingtip); separate memory only; -O2; OMP_TARGET_OFFLOAD=mandatory
! - build: gfortran -fopenacc -foffload=amdgcn-amdhsa -foffload-options=amdgcn-amdhsa=-march=gfx90a -O2 (gcc_g90);
!   -foffload=nvptx-none -foffload-options=nvptx-none=-march=sm_80 -foffload-options=nvptx-none=-latomic -O2 (gcc_sm80)
! - failure: rejected: Unclassifiable OpenACC directive
! - observed: `Error: Unclassifiable OpenACC directive at (1)` at `!$acc init` (also `!$acc set`, `!$acc shutdown`, and set's
!   default_async and device_num clauses), on both GPUs. The C programs of the same directives compile.
! - expected: compiles; `RESULT ran_on_host=0 check=pass`
! - spec: the init directive (OpenACC 3.4 §2.14.1 l.3089-3100), "In Fortran the syntax of the init directive is: !$acc init
!   [clause-list]"; the shutdown directive (§2.14.2) and the set directive (§2.14.3). They were added in OpenACC 2.5 (the
!   specification's "Changes from Version 2.0 to 2.5", margin lines 590-591).
! - GCC 16.2 documentation (libgomp.texi "Enabling OpenACC"): "A complete description of all OpenACC directives accepted may be
!   found in the OpenACC Application Programming Interface manual, version 2.6"; _OPENACC is 201711 (2.6). No list of OpenACC gaps
!   is documented.
! - other families: NVHPC 25.11/26.9 compile and run the programs (separate and managed memory); CCE 19/20/21 compile them and abort
!   at run time (cce-acc-init-set-runtime-assert.f90).
! - gate and confirmer: 10 cells (5 gcc_g90, 5 gcc_sm80), each confirmed in the gate's four environments (a-d;
!   results/gcc/gate-tioga/ and gate-wingtip/ verdicts.jsonl); confirmer verdicts (results/gcc/confirm/batch.gcc_*.jsonl):
!   compiler_bug (R11-compile-rejection) 10
! - catalog programs (5): acc34-clause-default_async, acc34-clause-device_num, acc34-directive-init, acc34-directive-set,
!   acc34-directive-shutdown
! - legality: the catalog programs are legal by construction (offload.engine.gen, c_gen and acc_gen
!   check every program against the catalog rules and the offload scope as it is built; no
!   compiler). GCC is a compiler under test only: never a legality witness, here or for another
!   family's case (catalog/machines.yaml under_test_only).
! Generated by compliance.gen (OpenACC 3.4, free-form Fortran). Do not edit.
! id: acc34-directive-init
! primary atom: acc.directive.init
! legal: yes
! observable: no (unverified: the check covers the device kernel, not the atom)
! ran_on_host: inside the compute region of interest (acc_on_device)
! evidence: unverified
! needs: none
! std: f2008
! unverified (needs_other_infrastructure): initialisation is observable only as timing or through the profiling interface (3.4
! chapter 5); the runtime initialises on first use anyway
program gen_prog
  use openacc, only: acc_device_host, acc_on_device
  implicit none
  integer, parameter :: n = 64
  integer, allocatable, target :: a(:), b(:)
  integer :: ref(n)
  integer :: i, host_flag
  logical :: ok
  allocate(a(n), b(n))
  do i = 1, n
    a(i) = i
    b(i) = 0
    ref(i) = 2*i + 1
  end do
  host_flag = 1
  !$acc init
  !$acc parallel loop copyin(a) copyout(b) copy(host_flag)
  do i = 1, n
    if (i == 1) host_flag = merge(1, 0, acc_on_device(acc_device_host))
    b(i) = 2*a(i) + 1
  end do
  ok = all(b == ref)
  print '(a,i0,a,a)', 'RESULT ran_on_host=', host_flag, ' check=', merge('pass', 'fail', ok)
  deallocate(a, b)
end program gen_prog