Hi Junio
On 23/11/2023 06:00, Junio C Hamano wrote:
"git checkout -B <branch> [<start-point>]", being a "forced" version
of "-b", switches to the <branch>, after optionally resetting its
tip to the <start-point>, even if the <branch> is in use in another
worktree, which is somewhat unexpected.
Protect the <branch> using the same logic that forbids "git checkout
<branch>" from touching a branch that is in use elsewhere.
This is a breaking change that may deserve backward compatibliity
warning in the Release Notes. The "--ignore-other-worktrees" option
can be used as an escape hatch if the finger memory of existing
users depend on the current behaviour of "-B".
I think this change makes sense and I found the implementation here much
easier to understand than a previous attempt at
https://lore.kernel.org/git/20230120113553.24655-1-carenas@xxxxxxxxx/
Reported-by: Willem Verstraeten <willem.verstraeten@xxxxxxxxx>
Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
---
* The documentation might also need updates, but I didn't look at.
This option is documented as an atomic version of
git branch -f <branch> [<start-point>]
git checkout <branch>
However "git branch -f <branch>" will fail if the branch is checked out
in the current worktree whereas "git checkout -B" succeeds. I think
allowing the checkout in that case makes sense for "git checkout -B" but
it does mean that description is not strictly accurate. I'm not sure it
matters that much though.
The documentation for "switch -C" is a bit lacking compared to "checkout
-B" but that is a separate problem.
builtin/checkout.c | 7 +++++++
t/t2060-switch.sh | 2 ++
t/t2400-worktree-add.sh | 8 ++++++++
3 files changed, 17 insertions(+)
diff --git a/builtin/checkout.c b/builtin/checkout.c
index b4ab972c5a..8a8ad23e98 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1600,6 +1600,13 @@ static int checkout_branch(struct checkout_opts *opts,
if (new_branch_info->path && !opts->force_detach && !opts->new_branch)
die_if_switching_to_a_branch_in_use(opts, new_branch_info->path);
+ /* "git checkout -B <branch>" */
+ if (opts->new_branch_force) {
+ char *full_ref = xstrfmt("refs/heads/%s", opts->new_branch);
+ die_if_switching_to_a_branch_in_use(opts, full_ref);
+ free(full_ref);
At the moment this is academic as neither of the test scripts changed by
this patch are leak free and so I don't think we need to worry about it
but it raises an interesting question about how we should handle memory
leaks when dying. Leaving the leak when dying means that a test script
that tests an expected failure will never be leak free but using
UNLEAK() would mean we miss a leak being introduced in the successful
case should the call to "free()" ever be removed. We could of course
rename die_if_checked_out() to error_if_checked_out() and return an
error instead of dying but that seems like a lot of churn just to keep
the leak checker happy.
Best Wishes
Phillip
+ }
+
if (!new_branch_info->commit && opts->new_branch) {
struct object_id rev;
int flag;
diff --git a/t/t2060-switch.sh b/t/t2060-switch.sh
index e247a4735b..c91c4db936 100755
--- a/t/t2060-switch.sh
+++ b/t/t2060-switch.sh
@@ -170,8 +170,10 @@ test_expect_success 'switch back when temporarily detached and checked out elsew
# we test in both worktrees to ensure that works
# as expected with "first" and "next" worktrees
test_must_fail git -C wt1 switch shared &&
+ test_must_fail git -C wt1 switch -C shared &&
git -C wt1 switch --ignore-other-worktrees shared &&
test_must_fail git -C wt2 switch shared &&
+ test_must_fail git -C wt2 switch -C shared &&
git -C wt2 switch --ignore-other-worktrees shared
'
diff --git a/t/t2400-worktree-add.sh b/t/t2400-worktree-add.sh
index df4aff7825..bbcb2d3419 100755
--- a/t/t2400-worktree-add.sh
+++ b/t/t2400-worktree-add.sh
@@ -126,6 +126,14 @@ test_expect_success 'die the same branch is already checked out' '
)
'
+test_expect_success 'refuse to reset a branch in use elsewhere' '
+ (
+ cd here &&
+ test_must_fail git checkout -B newmain 2>actual &&
+ grep "already used by worktree at" actual
+ )
+'
+
test_expect_success SYMLINKS 'die the same branch is already checked out (symlink)' '
head=$(git -C there rev-parse --git-path HEAD) &&
ref=$(git -C there symbolic-ref HEAD) &&
