Merge branch 'js/maint-graft-unhide-true-parents'

* js/maint-graft-unhide-true-parents:
  git repack: keep commits hidden by a graft
  Add a test showing that 'git repack' throws away grafted-away parents

Conflicts:
	git-repack.sh

7 files changed, 31 insertions, 3 deletions

diff --git a/Documentation/git-pack-objects.txt b/Documentation/git-pack-objects.txt
index 7d4c1a7556..2e4992970e 100644
--- a/Documentation/git-pack-objects.txt
+++ b/Documentation/git-pack-objects.txt
@@ -11,7 +11,8 @@ SYNOPSIS
 [verse]
 'git pack-objects' [-q] [--no-reuse-delta] [--delta-base-offset] [--non-empty]
 	[--local] [--incremental] [--window=N] [--depth=N] [--all-progress]
-	[--revs [--unpacked | --all]*] [--stdout | base-name] < object-list
+	[--revs [--unpacked | --all]*] [--stdout | base-name]
+	[--keep-true-parents] < object-list
 
 
 DESCRIPTION
@@ -197,6 +198,10 @@ base-name::
 	to force the version for the generated pack index, and to force
 	64-bit index entries on objects located above the given offset.
 
+--keep-true-parents::
+	With this option, parents that are hidden by grafts are packed
+	nevertheless.
+
 
 Author
 ------
diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index a27c2f6277..ef4bf6bc14 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -2255,6 +2255,10 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 				die("bad %s", arg);
 			continue;
 		}
+		if (!strcmp(arg, "--keep-true-parents")) {
+			grafts_replace_parents = 0;
+			continue;
+		}
 		usage(pack_usage);
 	}
 
diff --git a/cache.h b/cache.h
index c72f125bd4..e6c7f3307d 100644
--- a/cache.h
+++ b/cache.h
@@ -560,6 +560,8 @@ enum object_creation_mode {
 
 extern enum object_creation_mode object_creation_mode;
 
+extern int grafts_replace_parents;
+
 #define GIT_REPO_VERSION 0
 extern int repository_format_version;
 extern int check_repository_format(void);
diff --git a/commit.c b/commit.c
index a47fb4da27..e2bcbe8149 100644
--- a/commit.c
+++ b/commit.c
@@ -262,7 +262,11 @@ int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 		    bufptr[47] != '\n')
 			return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 		bufptr += 48;
-		if (graft)
+		/*
+		 * The clone is shallow if nr_parent < 0, and we must
+		 * not traverse its real parents even when we unhide them.
+		 */
+		if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 			continue;
 		new_parent = lookup_commit(parent);
 		if (new_parent)
diff --git a/environment.c b/environment.c
index 720f26b67d..8f5eaa7dd8 100644
--- a/environment.c
+++ b/environment.c
@@ -47,6 +47,7 @@ enum push_default_type push_default = PUSH_DEFAULT_MATCHING;
 #define OBJECT_CREATION_MODE OBJECT_CREATION_USES_HARDLINKS
 #endif
 enum object_creation_mode object_creation_mode = OBJECT_CREATION_MODE;
+int grafts_replace_parents = 1;
 
 /* Parallel index stat data preload? */
 int core_preload_index = 0;
diff --git a/git-repack.sh b/git-repack.sh
index 1bf239499c..1eb3bca352 100755
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -81,7 +81,7 @@ case ",$all_into_one," in
 esac
 
 args="$args $local ${GIT_QUIET:+-q} $no_reuse$extra"
-names=$(git pack-objects --honor-pack-keep --non-empty --all --reflog $args </dev/null "$PACKTMP") ||
+names=$(git pack-objects --keep-true-parents --honor-pack-keep --non-empty --all --reflog $args </dev/null "$PACKTMP") ||
 	exit 1
 if [ -z "$names" ]; then
 	say Nothing new to pack.
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 87c9b0e121..f4aa054750 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -149,5 +149,17 @@ test_expect_success 'local packed unreachable obs that exist in alternate ODB ar
 	test_must_fail git show $csha1
 '
 
+test_expect_success 'objects made unreachable by grafts only are kept' '
+	test_tick &&
+	git commit --allow-empty -m "commit 4" &&
+	H0=$(git rev-parse HEAD) &&
+	H1=$(git rev-parse HEAD^) &&
+	H2=$(git rev-parse HEAD^^) &&
+	echo "$H0 $H2" > .git/info/grafts &&
+	git reflog expire --expire=now --expire-unreachable=now --all &&
+	git repack -a -d &&
+	git cat-file -t $H1
+	'
+
 test_done