Re: git worktrees must exist even if locked

On Thu, May 11, 2017 at 3:24 AM, taylor, david [off-list ref] wrote:

The Git documentation in describing worktrees says that one reason
why you might want to lock a worktree is to prevent it from being pruned
if it is on a removable media that isn't currently mounted.

So, my expectation was that if the worktree is inaccessible (and locked), Git
would pretend that there is no worktree by that name.

In reality, if you have such a worktree, Git gets an error.

 On local systems, /home is local to a machine; home directories are elsewhere.
Home directories are NFS mounted; /home is not.

. create a repository in /my/home/dir/my-repo.git with

    git clone --bare <some arguments>

. create an empty directory /home/somedir/worktree-tests

. use 'git worktree add' to add /home/somedir/worktree-tests/<branch-name>
  as a worktree on branch <branch-name>.  It gets populated with the correct
  content.

. lock it using'git worktree lock'

So far, so good.  Now, go to a different computer -- one on which
/home/somedir/worktree-tests does not exist (and therefore
/home/somedir/worktree-tests/<branch-name> does not exist).

. cd /my/home/dir/my-repo.git

Now, try issuing Git commands.  Many will fail.

  git fetch ==> fails:

  fatal: Invalid path '/home/somedir/worktree-tests': No such file or directory

  git status ==> fails -- same error as above
  git help worktree ==> fails -- same error as above

FWIW I couldn't reproduce this. The fact that "git help" also fails
suggests this is triggered by some early setup code, which narrows
down the starting point to strbuf_realpath (that can print "Invalid
path", the other call in read-cache.c involves adding index entries
and can be ignored). But I fail to see how early setup code needs to
look at any worktree at all, especially when you issue command
standing from my-repo.git (i.e. bare repo setup, even current worktree
is ignored). An strace output, if possible, might help pinpoint the
problem.
-- 
Duy