Function can_cast_datetime64_metadata

numpy/core/src/multiarray/datetime.c:1389–1411

* This provides the casting rules for the DATETIME data type metadata. */

 * This provides the casting rules for the DATETIME data type metadata.
 */
NPY_NO_EXPORT npy_bool
can_cast_datetime64_metadata(PyArray_DatetimeMetaData *src_meta,
                             PyArray_DatetimeMetaData *dst_meta,
                             NPY_CASTING casting)
{
    switch (casting) {
        case NPY_UNSAFE_CASTING:
            return 1;

        case NPY_SAME_KIND_CASTING:
            return can_cast_datetime64_units(src_meta->base, dst_meta->base,
                                             casting);

        case NPY_SAFE_CASTING:
            return can_cast_datetime64_units(src_meta->base, dst_meta->base,
                                                             casting) &&
                   datetime_metadata_divides(src_meta, dst_meta, 0);

        default:
            return src_meta->base == dst_meta->base &&
                   src_meta->num == dst_meta->num;
    }
}

/*
 * This provides the casting rules for the TIMEDELTA data type metadata.