Given "git checkout --to <path> HEAD~1", the new worktree's HEAD should
begin life at the current branch's HEAD~1, however, it actually ends up
at HEAD~2. This happens because:
1. git-checkout resolves HEAD~1
2. to satisfy is_git_directory(), prepare_linked_worktree() creates
a HEAD for the new worktree with the value of the resolved HEAD~1
3. git-checkout re-invokes itself with the same arguments within the
new worktree to populate the worktree
4. the sub git-checkout resolves HEAD~1 relative to its own HEAD,
which is the resolved HEAD~1 from the original invocation,
resulting unexpectedly and incorrectly in HEAD~2 (relative to the
original)
Fix this by unconditionally assigning the current worktree's HEAD as the
value of the new worktree's HEAD.
As a side-effect, this change also eliminates a dependence within
prepare_linked_checkout() upon 'struct branch_info'. The plan is to
eventually relocate "git checkout --to" functionality to "git worktree
add", and worktree.c won't have knowledge of 'struct branch_info', so
removal of this dependency is a step toward that goal.
Signed-off-by: Eric Sunshine <sunshine@xxxxxxxxxxxxxx>
---
builtin/checkout.c | 16 ++++++++++++----
t/t2025-checkout-to.sh | 10 ++++++++++
2 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 2079aa4..5ada22a 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -863,6 +863,7 @@ static int prepare_linked_checkout(const struct checkout_opts *opts,
struct stat st;
struct child_process cp;
int counter = 0, len, ret;
+ unsigned char rev[20];
if (!new->commit)
die(_("no branch specified"));
@@ -920,13 +921,20 @@ static int prepare_linked_checkout(const struct checkout_opts *opts,
real_path(get_git_common_dir()), name);
/*
* This is to keep resolve_ref() happy. We need a valid HEAD
- * or is_git_directory() will reject the directory. Any valid
- * value would do because this value will be ignored and
- * replaced at the next (real) checkout.
+ * or is_git_directory() will reject the directory. Moreover, HEAD
+ * in the new worktree must resolve to the same value as HEAD in
+ * the current tree since the command invoked to populate the new
+ * worktree will be handed the branch/ref specified by the user.
+ * For instance, if the user asks for the new worktree to be based
+ * at HEAD~5, then the resolved HEAD~5 in the new worktree must
+ * match the resolved HEAD~5 in the current tree in order to match
+ * the user's expectation.
*/
+ if (!resolve_ref_unsafe("HEAD", 0, rev, NULL))
+ die(_("unable to resolve HEAD"));
strbuf_reset(&sb);
strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
- write_file(sb.buf, 1, "%s\n", sha1_to_hex(new->commit->object.sha1));
+ write_file(sb.buf, 1, "%s\n", sha1_to_hex(rev));
strbuf_reset(&sb);
strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
write_file(sb.buf, 1, "../..\n");
diff --git a/t/t2025-checkout-to.sh b/t/t2025-checkout-to.sh
index a8d9336..0fd731b 100755
--- a/t/t2025-checkout-to.sh
+++ b/t/t2025-checkout-to.sh
@@ -134,4 +134,14 @@ test_expect_success 'checkout with grafts' '
test_cmp expected actual
'
+test_expect_success 'checkout --to from relative HEAD' '
+ test_commit a &&
+ test_commit b &&
+ test_commit c &&
+ git rev-parse HEAD~1 >expected &&
+ git checkout --to relhead HEAD~1 &&
+ git -C relhead rev-parse HEAD >actual &&
+ test_cmp expected actual
+'
+
test_done
--
2.5.0.rc1.197.g417e668
--
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