builtin/reset: compute checkout metadata for reset

Pass the commit, and if we have it, the ref to the filters when we
perform a checkout.  This should only be the case when we invoke git
reset --hard; the metadata will be unused otherwise.

Signed-off-by: brian m. carlson <bk2204@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/reset.c

@@ -46,7 +46,7 @@ static inline int is_merge(void)
 	return !access(git_path_merge_head(the_repository), F_OK);
 }
 
-static int reset_index(const struct object_id *oid, int reset_type, int quiet)
+static int reset_index(const char *ref, const struct object_id *oid, int reset_type, int quiet)
 {
 	int i, nr = 0;
 	struct tree_desc desc[2];
@@ -60,6 +60,7 @@ static int reset_index(const struct object_id *oid, int reset_type, int quiet)
 	opts.dst_index = &the_index;
 	opts.fn = oneway_merge;
 	opts.merge = 1;
+	init_checkout_metadata(&opts.meta, ref, oid, NULL);
 	if (!quiet)
 		opts.verbose_update = 1;
 	switch (reset_type) {
@@ -418,11 +419,20 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 				}
 			}
 		} else {
-			int err = reset_index(&oid, reset_type, quiet);
+			struct object_id dummy;
+			char *ref = NULL;
+			int err;
+
+			dwim_ref(rev, strlen(rev), &dummy, &ref);
+			if (ref && !starts_with(ref, "refs/"))
+				ref = NULL;
+
+			err = reset_index(ref, &oid, reset_type, quiet);
 			if (reset_type == KEEP && !err)
-				err = reset_index(&oid, MIXED, quiet);
+				err = reset_index(ref, &oid, MIXED, quiet);
 			if (err)
 				die(_("Could not reset index file to revision '%s'."), rev);
+			free(ref);
 		}
 
 		if (write_locked_index(&the_index, &lock, COMMIT_LOCK))

t/t0021-conversion.sh

@@ -447,7 +447,8 @@ test_expect_success PERL 'required process filter should filter data for various
 		git commit -m "test commit 3" &&
 		git checkout empty-branch &&
 		filter_git rebase --onto empty-branch master^^ master &&
-		META="ref=refs/heads/master treeish=$(git rev-parse --verify master)" &&
+		MASTER2=$(git rev-parse --verify master) &&
+		META="ref=refs/heads/master treeish=$MASTER2" &&
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
@@ -458,6 +459,35 @@ test_expect_success PERL 'required process filter should filter data for various
 			IN: smudge testsubdir/test3 '\''sq'\'',\$x=.r $META blob=$M3 $S3 [OK] -- OUT: $S3 . [OK]
 			STOP
 		EOF
+		test_cmp_exclude_clean expected.log debug.log &&
+
+		git reset --hard empty-branch &&
+		filter_git reset --hard $MASTER &&
+		META="treeish=$MASTER" &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: smudge test.r $META blob=$M $S [OK] -- OUT: $S . [OK]
+			IN: smudge test2.r $META blob=$M2 $S2 [OK] -- OUT: $S2 . [OK]
+			IN: smudge test4-empty.r $META blob=$EMPTY 0 [OK] -- OUT: 0  [OK]
+			IN: smudge testsubdir/test3 '\''sq'\'',\$x=.r $META blob=$M3 $S3 [OK] -- OUT: $S3 . [OK]
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log debug.log &&
+
+		git branch old-master $MASTER &&
+		git reset --hard empty-branch &&
+		filter_git reset --hard old-master &&
+		META="ref=refs/heads/old-master treeish=$MASTER" &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: smudge test.r $META blob=$M $S [OK] -- OUT: $S . [OK]
+			IN: smudge test2.r $META blob=$M2 $S2 [OK] -- OUT: $S2 . [OK]
+			IN: smudge test4-empty.r $META blob=$EMPTY 0 [OK] -- OUT: 0  [OK]
+			IN: smudge testsubdir/test3 '\''sq'\'',\$x=.r $META blob=$M3 $S3 [OK] -- OUT: $S3 . [OK]
+			STOP
+		EOF
 		test_cmp_exclude_clean expected.log debug.log
 	)
 '