Subject: Re: [PATCH v2 6/6] worktree: new command to fix up worktree's info after moving

From: Junio C Hamano <[email-masked]>
Date: Tue, 19 Jan 2016 10:25:31 -0800

Nguyễn Thái Ngọc Duy  <[email-masked]> writes:

> This is a low-level command that can be used to correct worktree
> information after a worktree is moved. The idea is like 'index refresh'.
> In future we may do "worktree refresh" automatically to keep it from
> being pruned.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <[email-masked]>
> ---

I cannot help but think this is backwards.

Before this step, the users were essentially forbidden from using
"mv" to move a worktree, as doing so without telling Git can make
things inconsistent.  Why not keep that prohibition, and give one
and only official supported way to move a worktree, e.g. "worktree
mv", that explicitly tells Git what is being moved from where to
where?

It is prudent to avoid having to do things automatically, especially
that you already were burned once to be overly clever by doing
things automatically, no?  And telling users not to "mv" and instead
to use "worktree mv" would be one way to avoid having to "refresh"
automatically.

>  Documentation/git-worktree.txt |  8 +++++++-
>  builtin/worktree.c             | 18 ++++++++++++++++++
>  t/t1501-worktree.sh            |  9 +++++++++
>  3 files changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
> index 62c76c1..306aeec 100644
> --- a/Documentation/git-worktree.txt
> +++ b/Documentation/git-worktree.txt
> @@ -12,6 +12,7 @@ SYNOPSIS
>  'git worktree add' [-f] [--detach] [-b <new-branch>] <path> [<branch>]
>  'git worktree prune' [-n] [-v] [--expire <expire>]
>  'git worktree list' [--porcelain]
> +'git worktree refresh'
>  
>  DESCRIPTION
>  -----------
> @@ -65,6 +66,11 @@ each of the linked worktrees.  The output details include if the worktree is
>  bare, the revision currently checked out, and the branch currently checked out
>  (or 'detached HEAD' if none).
>  
> +refresh::
> +
> +This command is required to update worktree's information after it's moved.
> +Executed from inside the moved worktree.
> +
>  OPTIONS
>  -------
>  
> @@ -140,7 +146,7 @@ in the entry's directory. For example, if a linked working tree is moved
>  to `/newpath/test-next` and its `.git` file points to
>  `/path/main/.git/worktrees/test-next`, then update
>  `/path/main/.git/worktrees/test-next/gitdir` to reference `/newpath/test-next`
> -instead.
> +instead. Alternatively you can run "git worktree refresh".
>  
>  To prevent a $GIT_DIR/worktrees entry from being pruned (which
>  can be useful in some situations, such as when the
> diff --git a/builtin/worktree.c b/builtin/worktree.c
> index 475b958..0183ce0 100644
> --- a/builtin/worktree.c
> +++ b/builtin/worktree.c
> @@ -445,6 +445,22 @@ static int list(int ac, const char **av, const char *prefix)
>  	return 0;
>  }
>  
> +static int refresh(int ac, const char **av, const char *prefix)
> +{
> +	const char *gitdir;
> +
> +	if (ac != 1)
> +		die(_("Arguments not expected"));
> +
> +	gitdir = git_pathdup("gitdir");
> +	if (access(gitdir, F_OK))
> +		return 0;
> +	if (!startup_info->first_gitfile)
> +		die("BUG: .git file's location not found");
> +	write_file(gitdir, "%s", startup_info->first_gitfile);
> +	return 0;
> +}
> +
>  int cmd_worktree(int ac, const char **av, const char *prefix)
>  {
>  	struct option options[] = {
> @@ -459,5 +475,7 @@ int cmd_worktree(int ac, const char **av, const char *prefix)
>  		return prune(ac - 1, av + 1, prefix);
>  	if (!strcmp(av[1], "list"))
>  		return list(ac - 1, av + 1, prefix);
> +	if (!strcmp(av[1], "refresh"))
> +		return refresh(ac - 1, av + 1, prefix);
>  	usage_with_options(worktree_usage, options);
>  }
> diff --git a/t/t1501-worktree.sh b/t/t1501-worktree.sh
> index cc5b870..821831b 100755
> --- a/t/t1501-worktree.sh
> +++ b/t/t1501-worktree.sh
> @@ -423,4 +423,13 @@ test_expect_success '$GIT_WORK_TREE overrides $GIT_DIR/common' '
>  	)
>  '
>  
> +test_expect_success 'worktree refresh corrects gitdir file' '
> +	git worktree add test-refresh &&
> +	P=repo.git/worktrees/test-refresh/gitdir &&
> +	echo corrupt >$P &&
> +	git -C test-refresh worktree refresh &&
> +	echo "$TRASH_DIRECTORY/test-refresh/.git" >expected &&
> +	test_cmp expected $P
> +'
> +
>  test_done