pack-objects: allow --filter without --stdout

9535ce7 (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 9e27bea
(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 <[email protected]>
Signed-off-by: Christian Couder <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: chriscool

Documentation/git-pack-objects.txt

@@ -296,8 +296,8 @@ 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::

builtin/pack-objects.c

@@ -4402,12 +4402,8 @@ 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"));

t/t5317-pack-objects-filter-objects.sh

@@ -53,6 +53,14 @@ test_expect_success 'verify blob:none packfile has no blobs' '
 	! grep blob verify_result
 '
 
+test_expect_success 'verify blob:none packfile without --stdout' '
+	git -C r1 pack-objects --revs --filter=blob:none mypackname >packhash <<-EOF &&
+	HEAD
+	EOF
+	git -C r1 verify-pack -v "mypackname-$(cat packhash).pack" >verify_result &&
+	! grep blob verify_result
+'
+
 test_expect_success 'verify normal and blob:none packfiles have same commits/trees' '
 	git -C r1 verify-pack -v ../all.pack >verify_result &&
 	grep -E "commit|tree" verify_result |