[PATCH v2 7/8] builtin/repack.c: avoid directly inspecting "util"

[Taylor Blau <me@xxxxxxxxxxxx>]

The `->util` field corresponding to each string_list_item is used to
track the existence of some pack at the beginning of a repack operation
was originally intended to be used as a bitfield.

This bitfield tracked:

  - (1 << 0): whether or not the pack should be deleted
  - (1 << 1): whether or not the pack is cruft

The previous commit removed the use of the second bit, but a future
patch (from a different series than this one) will introduce a new use
of it.

So we could stop treating the util pointer as a bitfield and instead
start treating it as if it were a boolean. But this would require some
backtracking when that later patch is applied.

Instead, let's avoid touching the ->util field directly, and instead
introduce convenience functions like:

  - pack_mark_for_deletion()
  - pack_is_marked_for_deletion()

Helped-by: Junio C Hamano <gitster@xxxxxxxxx>
Helped-by: Jeff King <peff@xxxxxxxx>
Helped-by: Patrick Steinhardt <ps@xxxxxx>
Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx>
---
 builtin/repack.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/builtin/repack.c b/builtin/repack.c
index 8103a9d308..e9a091fbbc 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -111,6 +111,16 @@ static int has_existing_non_kept_packs(const struct existing_packs *existing)
 	return existing->non_kept_packs.nr || existing->cruft_packs.nr;
 }
 
+static void pack_mark_for_deletion(struct string_list_item *item)
+{
+	item->util = (void*)((uintptr_t)item->util | DELETE_PACK);
+}
+
+static int pack_is_marked_for_deletion(struct string_list_item *item)
+{
+	return (uintptr_t)item->util & DELETE_PACK;
+}
+
 static void mark_packs_for_deletion_1(struct string_list *names,
 				      struct string_list *list)
 {
@@ -130,7 +140,7 @@ static void mark_packs_for_deletion_1(struct string_list *names,
 		 * (if `-d` was given).
 		 */
 		if (!string_list_has_string(names, sha1))
-			item->util = (void*)(uintptr_t)((size_t)item->util | DELETE_PACK);
+			pack_mark_for_deletion(item);
 	}
 }
 
@@ -158,7 +168,7 @@ static void remove_redundant_packs_1(struct string_list *packs)
 {
 	struct string_list_item *item;
 	for_each_string_list_item(item, packs) {
-		if (!((uintptr_t)item->util & DELETE_PACK))
+		if (!pack_is_marked_for_deletion(item))
 			continue;
 		remove_redundant_pack(packdir, item->string);
 	}
@@ -702,13 +712,13 @@ static void midx_included_packs(struct string_list *include,
 		}
 	} else {
 		for_each_string_list_item(item, &existing->non_kept_packs) {
-			if ((uintptr_t)item->util & DELETE_PACK)
+			if (pack_is_marked_for_deletion(item))
 				continue;
 			string_list_insert(include, xstrfmt("%s.idx", item->string));
 		}
 
 		for_each_string_list_item(item, &existing->cruft_packs) {
-			if ((uintptr_t)item->util & DELETE_PACK)
+			if (pack_is_marked_for_deletion(item))
 				continue;
 			string_list_insert(include, xstrfmt("%s.idx", item->string));
 		}
-- 
2.42.0.166.g68748eb9c8