driver_validate Subroutine

   subroutine driver_validate(cfg, ierr)
      !! `rdb --validate-only`: everything `driver_run` does before the
      !! first step that can REFUSE a configuration — the full
      !! `engine_setup` sequence, so every fail-loud configure-time check
      !! in the `configure_ocean_*` stages (`rdb_ocean_setup.F90`), the
      !! stability audit and the IC seed — and nothing after it: no device
      !! mapping, no stepping, no output files (the diag stream is not
      !! opened; see `engine_setup`'s `validate_only`).
      !!
      !! `validate_config` is the caller's job (it runs on the bare config,
      !! before the process grid exists).  `ierr` is `OCEAN_STATUS_OK` when
      !! the configuration is accepted, else the `rdb_ocean_status` code of
      !! the refusing stage, whose reason has already been logged.  A stage
      !! that has no `ierr` path still `error stop`s, which is a refusal
      !! with a non-zero exit too.
      type(config_t), intent(inout) :: cfg
      integer, intent(out) :: ierr

      type(ocean_engine_t) :: engine

      call engine_setup(engine, cfg, ierr, compute_rank=comm_env_compute_rank(), &
                        compute_size=comm_env_compute_size(), mpi_rank=comm_env_rank(), &
                        restart_file=cfg%restart_file, validate_only=.true.)
      ! A refused setup leaves a partially-built engine; the process is
      ! about to exit, so only an accepted one is torn down.
      if (ierr == OCEAN_STATUS_OK) call engine_teardown(engine)
   end subroutine driver_validate