[PATCH 1/9] pack-objects: allow `--filter` without `--stdout`

9535ce7337 (pack-objects: add list-objects filtering, 2017-11-21)
taught `git pack-objects` to use `--filter`, but required the use of
`--stdout` since a partial clone mechanism was not yet in place to
handle missing objects. Since then, changes like 9e27beaa23
(promisor-remote: implement promisor_remote_get_direct(), 2019-06-25)
and others added support to dynamically fetch objects that were missing.

Even without a promisor remote, filtering out objects can also be useful
if we can put the filtered out objects in a separate pack, and in this
case it also makes sense for pack-objects to write the packfile directly
to an actual file rather than on stdout.

Remove the `--stdout` requirement when using `--filter`, so that in a
follow-up commit, repack can pass `--filter` to pack-objects to omit
certain objects from the resulting packfile.

Signed-off-by: John Cai <redacted>
Signed-off-by: Christian Couder <redacted>
---
 Documentation/git-pack-objects.txt | 4 ++--
 builtin/pack-objects.c             | 8 ++------
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/Documentation/git-pack-objects.txt b/Documentation/git-pack-objects.txt
index a9995a932c..583270a85f 100644
--- a/Documentation/git-pack-objects.txt
+++ b/Documentation/git-pack-objects.txt

@@ -298,8 +298,8 @@ So does `git bundle` (see linkgit:git-bundle[1]) when it creates a bundle.
 	nevertheless.
 
 --filter=<filter-spec>::
-	Requires `--stdout`.  Omits certain objects (usually blobs) from
-	the resulting packfile.  See linkgit:git-rev-list[1] for valid
+	Omits certain objects (usually blobs) from the resulting
+	packfile.  See linkgit:git-rev-list[1] for valid
 	`<filter-spec>` forms.
 
 --no-filter::

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 9cfc8801f9..af007868c1 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c

@@ -4388,12 +4388,8 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	if (!rev_list_all || !rev_list_reflog || !rev_list_index)
 		unpack_unreachable_expiration = 0;
 
-	if (filter_options.choice) {
-		if (!pack_to_stdout)
-			die(_("cannot use --filter without --stdout"));
-		if (stdin_packs)
-			die(_("cannot use --filter with --stdin-packs"));
-	}
+	if (stdin_packs && filter_options.choice)
+		die(_("cannot use --filter with --stdin-packs"));
 
 	if (stdin_packs && use_internal_rev_list)
 		die(_("cannot use internal rev list with --stdin-packs"));

-- 
2.41.0.37.gae45d9845e