"brian m. carlson" <sandals@xxxxxxxxxxxxxxxxxxxx> writes:
> When we call init_checkout_metadata in reset_tree, we want to pass the
> object ID of the commit in question so that it can be passed to filters,
> or if there is no commit, the tree. We anticipated this latter case,
> which can occur elsewhere in the checkout code, but it cannot occur
> here, since reset_tree is called only (indirectly) via switch_branches,
> which requires that we have a valid commit. switch_branches dies if we
> lack a name and cannot produce a commit from HEAD, and its caller dies
> if we do have a branch name but still lack a commit pointer.
>
> Since we know we must always have a valid commit structure in this case,
> let's remove the dead code paths and just refer to the commit structure.
> This simplifies the code and makes it easier for the reader.
builtin/checkout.c::merge_working_tree() has these lines in its
earlier part:
if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
if (new_branch_info->commit)
BUG("'switch --orphan' should never acc...");
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(new_tree, opts, 1, writeout_error, new_branch_info);
if (ret)
return ret;
...
So, when orphan && orphan-from-empty are both set, we must not have
commit, and then if discard is also there, we end up passing
new_brnach_info that has NULL in its commit.
There are few more callers of reset_tree() in this function, which I
did not trace.
Perhaps the "orphan && orphan-from-empty" is a dead combination and
we won't hit the codepath and that is why this change is safe? I
dunno.
> Signed-off-by: brian m. carlson <sandals@xxxxxxxxxxxxxxxxxxxx>
> ---
> builtin/checkout.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index e9d111bb83..e53bdab5b8 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -620,11 +620,7 @@ static int reset_tree(struct tree *tree, const struct checkout_opts *o,
> opts.verbose_update = o->show_progress;
> opts.src_index = &the_index;
> opts.dst_index = &the_index;
> - init_checkout_metadata(&opts.meta, info->refname,
> - info->commit ? &info->commit->object.oid :
> - is_null_oid(&info->oid) ? &tree->object.oid :
> - &info->oid,
> - NULL);
> + init_checkout_metadata(&opts.meta, info->refname, &info->commit->object.oid, NULL);
> parse_tree(tree);
> init_tree_desc(&tree_desc, tree->buffer, tree->size);
> switch (unpack_trees(1, &tree_desc, &opts)) {
