pass subcommand "prefix" arguments to parse_options()

Recent commits such as bf0a6b65fc (builtin/multi-pack-index.c: let
parse-options parse subcommands, 2022-08-19) converted a few functions
to match our usual argc/argv/prefix conventions, but the prefix argument
remains unused.

However, there is a good use for it: they should pass it to their own
parse_options() functions, where it may be used to adjust the value of
any filename options. In all but one of these functions, there's no
behavior change, since they don't use OPT_FILENAME. But this is an
actual fix for one option, which you can see by modifying the test suite
like so:

	diff --git a/t/t5326-multi-pack-bitmaps.sh b/t/t5326-multi-pack-bitmaps.sh
	index 4fe57414c1..d0974d4371 100755
	--- a/t/t5326-multi-pack-bitmaps.sh
	+++ b/t/t5326-multi-pack-bitmaps.sh
	@@ -186,7 +186,11 @@ test_expect_success 'writing a bitmap with --refs-snapshot' '

	 		# Then again, but with a refs snapshot which only sees
	 		# refs/tags/one.
	-		git multi-pack-index write --bitmap --refs-snapshot=snapshot &&
	+		(
	+			mkdir subdir &&
	+			cd subdir &&
	+			git multi-pack-index write --bitmap --refs-snapshot=../snapshot
	+		) &&

	 		test_path_is_file $midx &&
	 		test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&

I'd emphasize that this wasn't broken by bf0a6b65fc; it has been broken
all along, because the sub-function never got to see the prefix. It is
that commit which is actually enabling us to fix it (and which also
brought attention to the problem because it triggers -Wunused-parameter!)

The other functions changed here don't use OPT_FILENAME at all. In their
cases this isn't fixing anything visible, but it's following the usual
pattern and future-proofing them against somebody adding new options and
being surprised.

I didn't include a test for the one visible case above. We don't
generally test routine parse-options behavior for individual options.
The challenge here was finding the problem, and now that this has been
done, it's not likely to regress. Likewise, we could apply the patch
above to cover it "for free" but it makes reading the rest of the test
unnecessarily complicated.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 7b39a150a9..287716db68 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -60,7 +60,7 @@ static int sparse_checkout_list(int argc, const char **argv, const char *prefix)
 	if (!core_apply_sparse_checkout)
 		die(_("this worktree is not sparse"));
 
-	argc = parse_options(argc, argv, NULL,
+	argc = parse_options(argc, argv, prefix,
 			     builtin_sparse_checkout_list_options,
 			     builtin_sparse_checkout_list_usage, 0);
 
@@ -452,7 +452,7 @@ static int sparse_checkout_init(int argc, const char **argv, const char *prefix)
 	init_opts.cone_mode = -1;
 	init_opts.sparse_index = -1;
 
-	argc = parse_options(argc, argv, NULL,
+	argc = parse_options(argc, argv, prefix,
 			     builtin_sparse_checkout_init_options,
 			     builtin_sparse_checkout_init_usage, 0);
 
@@ -860,7 +860,7 @@ static int sparse_checkout_reapply(int argc, const char **argv,
 	reapply_opts.cone_mode = -1;
 	reapply_opts.sparse_index = -1;
 
-	argc = parse_options(argc, argv, NULL,
+	argc = parse_options(argc, argv, prefix,
 			     builtin_sparse_checkout_reapply_options,
 			     builtin_sparse_checkout_reapply_usage, 0);
 
@@ -897,7 +897,7 @@ static int sparse_checkout_disable(int argc, const char **argv,
 	 * forcibly return to a dense checkout regardless of initial state.
 	 */
 
-	argc = parse_options(argc, argv, NULL,
+	argc = parse_options(argc, argv, prefix,
 			     builtin_sparse_checkout_disable_options,
 			     builtin_sparse_checkout_disable_usage, 0);