Function patch_id_neq

patch-ids.c:39–67

* When we cannot load the full patch-id for both commits for whatever * reason, the function returns -1 (i.e. return error(...)). Despite * the "neq" in the name of this function, the caller only cares about * the return value being zero (a and b are equivalent) or non-zero (a * and b are different), and returning non-zero would keep both in the * result, even if they actually were equivalent

 * any significance; only that it is non-zero matters.
 */
static int patch_id_neq(const void *cmpfn_data,
			const struct hashmap_entry *eptr,
			const struct hashmap_entry *entry_or_key,
			const void *keydata UNUSED)
{
	/*
	 * We drop the 'const' modifier here intentionally.
	 *
	 * Even though eptr and entry_or_key are const, we want to
	 * lazily compute their .patch_id members; see b3dfeebb (rebase:
	 * avoid computing unnecessary patch IDs, 2016-07-29). So we cast
	 * the constness away with container_of().
	 */
	struct diff_options *opt = (void *)cmpfn_data;
	struct patch_id *a, *b;

	a = container_of(eptr, struct patch_id, ent);
	b = container_of(entry_or_key, struct patch_id, ent);

	if (is_null_oid(&a->patch_id) &&
	    commit_patch_id(a->commit, opt, &a->patch_id, 0))
		return error("Could not get patch ID for %s",
			oid_to_hex(&a->commit->object.oid));
	if (is_null_oid(&b->patch_id) &&
	    commit_patch_id(b->commit, opt, &b->patch_id, 0))
		return error("Could not get patch ID for %s",
			oid_to_hex(&b->commit->object.oid));
	return !oideq(&a->patch_id, &b->patch_id);
}

int init_patch_ids(struct repository *r, struct patch_ids *ids)
{