Re: [PATCH v2 0/3] Ensure unique worktree ids across repositories

[Caleb White <cdwhite3@pm.me>]

On Mon Dec 2, 2024 at 10:37 PM CST, Junio C Hamano wrote:
> Caleb White <cdwhite3@pm.me> writes:
>
>> You're correct in that the worktree ids are only relevant within the
>> context of a single repository. However, I've already demonstrated that
>> it's possible for a repository to "repair" (i.e., take over) a worktree
>> belonging to another repository if the ids match (inferred backlink).
>
> I know.  But isn't that a BUG in the code that "repair"s?  If a
> worktree had a name 'develop' that was OK in the context of
> repository X, and when you "repair" things so that it becomes one of
> the worktrees of a different repository Y, the "repair" operation is
> what MUST make sure that the worktree that used to be known as
> 'develop' to repository X does not interfere any existing worktrees
> that is attached to the repository Y.  If the repository Y already
> had a worktree called 'develop', the "repair" operation must make
> sure that the newly adopted worktree would get a different name.

No, this is incorrect---there should be no reason to "repair" a worktree
from another repository in the first place. That would be undefined
behavior and is indicative of a user mistake or unintentional repair
(e.g., it would make no sense for the php-src repository to repair
a worktree from this git repository). The repair operation is only
intended to be used with worktrees of the same repository.

> But then, the concern is exactly the same when you try to create a
> new worktree (no "repair" involved) in repository Y and try to give
> it a name 'develop', isn't it?  You have to make sure that there is
> no worktree that is called 'develop' in the repository Y before
> giving it the name.  Is it broken?  If not, what are we doing to
> make sure we won't give the name 'develop' to the new worktree?
> Certainly we do not use any hash or random number for that, so why
> does this new series need to use a random number?

We currently suffix an auto incrementing number in this use case, so 
you can have two `develop` worktrees (located in different directories
of course), and one will have an id of `develop` and the other will have
an id of `develop1`.

Best,