Switching and creating branches always involves knowing the
<start-point> to begin the new branch from. Sometimes, people want to
create a new branch that does not have any commits yet; --orphan is a
flag to allow that.
If <start-point> is not specified, instead of leaving index/worktree
unchanged, default to "empty tree" starting point, allowing a clean
start.
A note on the implementation. An alternative is just create a dummy
commit in-core with empty tree and switch to it. But there's a chance
the commit's SHA-1 may end up somewhere permanent like reflog. It's best
to make sure "commit" pointer is NULL to avoid it.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
builtin/checkout.c | 33 +++++++++++++++++++++++++--------
1 file changed, 25 insertions(+), 8 deletions(-)
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 21a585eaa9..f0d6207236 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -58,6 +58,7 @@ struct checkout_opts {
int switch_branch_doing_nothing_is_ok;
int only_merge_on_switching_branches;
int can_switch_when_in_progress;
+ int orphan_default_empty_tree;
const char *new_branch;
const char *new_branch_force;
@@ -568,15 +569,19 @@ static int merge_working_tree(const struct checkout_opts *opts,
{
int ret;
struct lock_file lock_file = LOCK_INIT;
+ struct tree *new_tree;
hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
if (read_cache_preload(NULL) < 0)
return error(_("index file corrupt"));
resolve_undo_clear();
+ if (opts->orphan_default_empty_tree && !new_branch_info->commit)
+ new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
+ else
+ new_tree = get_commit_tree(new_branch_info->commit);
if (opts->discard_changes) {
- ret = reset_tree(get_commit_tree(new_branch_info->commit),
- opts, 1, writeout_error);
+ ret = reset_tree(new_tree, opts, 1, writeout_error);
if (ret)
return ret;
} else {
@@ -614,7 +619,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
&old_branch_info->commit->object.oid :
the_hash_algo->empty_tree);
init_tree_desc(&trees[0], tree->buffer, tree->size);
- tree = parse_tree_indirect(&new_branch_info->commit->object.oid);
+ parse_tree(new_tree);
+ tree = new_tree;
init_tree_desc(&trees[1], tree->buffer, tree->size);
ret = unpack_trees(2, trees, &topts);
@@ -663,7 +669,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
o.verbosity = 0;
work = write_tree_from_memory(&o);
- ret = reset_tree(get_commit_tree(new_branch_info->commit),
+ ret = reset_tree(new_tree,
opts, 1,
writeout_error);
if (ret)
@@ -672,13 +678,13 @@ static int merge_working_tree(const struct checkout_opts *opts,
o.branch1 = new_branch_info->name;
o.branch2 = "local";
ret = merge_trees(&o,
- get_commit_tree(new_branch_info->commit),
+ new_tree,
work,
get_commit_tree(old_branch_info->commit),
&result);
if (ret < 0)
exit(128);
- ret = reset_tree(get_commit_tree(new_branch_info->commit),
+ ret = reset_tree(new_tree,
opts, 0,
writeout_error);
strbuf_release(&o.obuf);
@@ -696,7 +702,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
die(_("unable to write new index file"));
- if (!opts->discard_changes && !opts->quiet)
+ if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
return 0;
@@ -897,7 +903,10 @@ static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
add_pending_object(&revs, object, oid_to_hex(&object->oid));
for_each_ref(add_pending_uninteresting_ref, &revs);
- add_pending_oid(&revs, "HEAD", &new_commit->object.oid, UNINTERESTING);
+ if (new_commit)
+ add_pending_oid(&revs, "HEAD",
+ &new_commit->object.oid,
+ UNINTERESTING);
if (prepare_revision_walk(&revs))
die(_("internal error in revision walk"));
@@ -941,6 +950,12 @@ static int switch_branches(const struct checkout_opts *opts,
if (opts->only_merge_on_switching_branches)
do_merge = 0;
+
+ if (opts->new_orphan_branch && opts->orphan_default_empty_tree) {
+ new_branch_info->commit = NULL;
+ new_branch_info->name = "(empty)";
+ do_merge = 1;
+ }
}
if (do_merge) {
@@ -1537,6 +1552,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
opts.accept_pathspec = 1;
opts.implicit_detach = 1;
opts.can_switch_when_in_progress = 1;
+ opts.orphan_default_empty_tree = 0;
options = parse_options_dup(checkout_options);
options = add_common_options(&opts, options);
@@ -1575,6 +1591,7 @@ int cmd_switch(int argc, const char **argv, const char *prefix)
opts.only_merge_on_switching_branches = 1;
opts.implicit_detach = 0;
opts.can_switch_when_in_progress = 0;
+ opts.orphan_default_empty_tree = 1;
options = parse_options_dup(switch_options);
options = add_common_options(&opts, options);
--
2.21.0.548.gd3c7d92dc2
