checkout -p: handle tree arguments correctly again
This fixes a segmentation fault.
The bug is caused by dereferencing `new_branch_info->commit` when it is
`NULL`, which is the case when the tree-ish argument is actually a tree,
not a commit-ish. This was introduced in 5602b500c3c (builtin/checkout:
fix `git checkout -p HEAD...` bug, 2020-10-07), where we tried to ensure
that the special tree-ish `HEAD...` is handled correctly.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 9a33b00..728c67e 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -479,9 +479,11 @@ static int checkout_paths(const struct checkout_opts *opts,
* with the hex of the commit (whether it's in `...` form or
* not) for the run_add_interactive() machinery to work
* properly. However, there is special logic for the HEAD case
- * so we mustn't replace that.
+ * so we mustn't replace that. Also, when we were given a
+ * tree-object, new_branch_info->commit would be NULL, but we
+ * do not have to do any replacement, either.
*/
- if (rev && strcmp(rev, "HEAD"))
+ if (rev && new_branch_info->commit && strcmp(rev, "HEAD"))
rev = oid_to_hex_r(rev_oid, &new_branch_info->commit->object.oid);
if (opts->checkout_index && opts->checkout_worktree)
diff --git a/t/t2016-checkout-patch.sh b/t/t2016-checkout-patch.sh
index d91a329..abfd586 100755
--- a/t/t2016-checkout-patch.sh
+++ b/t/t2016-checkout-patch.sh
@@ -123,4 +123,9 @@
verify_saved_head
'
+test_expect_success PERL 'empty tree can be handled' '
+ test_when_finished "git reset --hard" &&
+ git checkout -p $(test_oid empty_tree) --
+'
+
test_done
