Re: [PATCH v2 1/3] worktree: remove "the_repository" from is_current_worktree()

[Phillip Wood <phillip.wood123@gmail.com>]

Hi Patrick

On 16/03/2026 07:38, Patrick Steinhardt wrote:
> On Sun, Mar 15, 2026 at 04:18:50PM +0000, Phillip Wood wrote:
>> From: Phillip Wood <phillip.wood@dunelm.org.uk>
>>
>> is_current_worktree() compares the gitdir of the worktree to the gitdir
>> of "the_repository" and returns true when they match. To get the gitdir
>> of the worktree it calls get_workree_git_dir() which also depends on
>> "the_repository". This has the effect that even if "wt->path" matches
>> "wt->repo->worktree" is_current_worktree(wt) will return false when
>> "wt->repo" is not "the_repository" which is confusing.
>>
>> The use of "the_repository" in is_current_wortree() comes from
>> replacing get_git_dir() with repo_get_git_dir() in 246deeac951
>> (environment: make `get_git_dir()` accept a repository, 2024-09-12). In
>> get_worktree_git_dir() it comes from replacing git_common_path() with
>> repo_common_path() in 07242c2a5af (path: drop `git_common_path()`
>> in favor of `repo_common_path()`, 2025-02-07). In both cases we have
>> a repository instance available so use that instead. This means
>> that a worktree "wt" is always considered current when "wt->path"
>> matches "wt->repo->worktree" and so the worktree returned by
>> get_worktree_from_repository() is always considered current.
>>
>> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
>> ---
>>   worktree.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/worktree.c b/worktree.c
>> index e9ff6e6ef2e..344ad0c031b 100644
>> --- a/worktree.c
>> +++ b/worktree.c
>> @@ -58,7 +58,7 @@ static void add_head_info(struct worktree *wt)
>>   
>>   static int is_current_worktree(struct worktree *wt)
>>   {
>> -	char *git_dir = absolute_pathdup(repo_get_git_dir(the_repository));
>> +	char *git_dir = absolute_pathdup(repo_get_git_dir(wt->repo));
>>   	char *wt_git_dir = get_worktree_git_dir(wt);
>>   	int is_current = !fspathcmp(git_dir, absolute_path(wt_git_dir));
>>   	free(wt_git_dir);
> 
> Hm, okay.
> 
>> @@ -78,7 +78,7 @@ struct worktree *get_worktree_from_repository(struct repository *repo)
>>   	wt->is_bare = !repo->worktree;
>>   	if (fspathcmp(gitdir, commondir))
>>   		wt->id = xstrdup(find_last_dir_sep(gitdir) + 1);
>> -	wt->is_current = is_current_worktree(wt);
>> +	wt->is_current = true;
>>   	add_head_info(wt);
>>   
>>   	free(gitdir);
> 
> I have been staring at this code for longer than I want to admit, and I
> still haven't convinced myself that this is not a change in behaviour.
> I think what I'm wondering about is what `is_current_worktree()` is
> actually intended to do. In other words, what _do_ we consider to be
> "current"?

There was some discussion about that in [1] where reviewers were 
surprised that we needed to call is_current_worktree() here. This change 
is consistent with the rest of the patch but you're right that it is a 
change in behavior as at the moment the "current" worktree is set by the 
worktree that the process was started in. In practice we only ever have 
a single struct repository instance per process so there is no practical 
change in behavior here. At the moment, if you visit a set of submodules 
from the superproject by forking one process per submodule each 
submodule worktree is considered "current", but if you visit them by 
spinning up some threads in the current process they are not considered 
"current". That seems to me to be inconsistent as the process started by 
the user is in the superproject in both cases.

The "is_current" field was added in [1] without any discussion in the 
commit message. It seems to have been added to stop the same branch 
being checked out in multiple worktrees [2].

Thanks

Phillip

[1] 750e8a60d69 (worktree.c: mark current worktree, 2016-04-22)
[2] 
https://lore.kernel.org/git/CAJZYdzhG8h3s=Ep1fuGbam1cWhYkv0tW6tQ7pBGGj+fj6=Nrsw@mail.gmail.com/


> I would consider the worktree "current" that the Git process
> has been invoked in. So if I pass a repo other than `the_repository`, or
> if I pass a worktree that is not the one that Git has been started in,
> then I would expect the function to return `false`. With that naive
> assumption your change would be breaking the existing logic.
> 
> But I have no idea whether my assumption is correct or not, as
> there is not really any documentation of what the function or of the
> `struct worktree::is_current` field. And having a look at a couple of
> callers doesn't really make me all the wiser.
> 
> It would be great if you could shine some light on this and then also
> add a bit of documentation to either the function, the field, or both :)
> 
> Thanks!
> 
> Patrick
>