Re: some apparent inaccuracies in "man git-worktree"

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Nov 14, 2017, 18:33 UTC
Message-ID: <CAPig+cRc7Yqeys=oPEgPnyR4qT7qKYLbH1ifnp+6F6N+mSzNVA@mail.gmail.com>
In-Reply-To: <alpine.LFD.2.21.1711140324580.12112@localhost.localdomain>

On Tue, Nov 14, 2017 at 3:43 AM, Robert P. J. Day <rpjday@crashcourse.ca> wrote:

Show 8 quoted lines

> from "man git-worktree", there seem to be some inaccuracies in the
> SYNOPSIS regarding the "add" subcommand:
>
>   git worktree add \
>     [-f] [--detach] [--checkout] [--lock] [-b <new-branch>] <path> [<branch>]
>
>   first, there's no mention of "-B" in that SYNOPSIS, even though it's
> explained further down the man page.

Omission of "-B" from the synopsis was intentional. From cbdf60fa18 (worktree: add -b/-B options, 2015-07-06):

    worktree: add -b/-B options

    One of git-worktree's roles is to populate the new worktree, much like
    git-checkout, and thus, for convenience, ought to support several of the
    same shortcuts. Toward this goal, add -b/-B options to create a new
    branch and check it out in the new worktree.

    (For brevity, only -b is mentioned in the synopsis; -B is omitted.)

Whether or not the omission was actually a good decision is questionable. The thinking, at the time, may have been that users already familiar with "-b" in 'git checkout' would likewise be familiar with (and be able to infer) "-B", thus it wasn't important to state its existence explicitly in the synopsis, which was already getting lengthy. Of course, that decision does not assist newcomers, so adding "-B" to the synopsis would help the page better stand on its own.

Show 6 quoted lines

>   next, the SYNOPSIS seems misleading as it doesn't make clear that
> the options -b, -B and --detach are mutually exclusive, which is made
> clear in the worktree.c source:
>
>     if (!!opts.detach + !!opts.new_branch + !!new_branch_force > 1)
>             die(_("-b, -B, and --detach are mutually exclusive"));

Failure to update the synopsis to indicate mutual exclusion appears to be a simple oversight in ab0b2c53ed (worktree: make --detach mutually exclusive with -b/-B, 2015-07-17) in response to: https://public-inbox.org/git/55A8F4B1.9060304@drmicha.warpmail.net/

Show 20 quoted lines

>   finally (and maybe i'm just not reading carefully enough), it's not
> clear what happens if you add a worktree at a given commit without
> specifying *any* of -b, -B or --detach. the obvious result should be a
> new worktree checked out at a detached HEAD and, interestingly, if i
> do that, then from the main tree, i see:
>
>   $ git worktree list
>   /home/rpjday/k/git   516fb7f2e73d [master]
>   /home/rpjday/k/temp  c470abd4fde4 (detached HEAD)
>   $
>
> but from within the worktree, if i ask for the status, i see only:
>
>   $ git status
>   Not currently on any branch.
>   nothing to commit, working tree clean
>   $
>
> where i would normally have expected to see "detached HEAD", is there
> a reason that's not displayed?

Someone more familiar with this bit can correct me if I'm wrong, but I believe that the "HEAD detached at/from <branch>" you normally see with 'git status' is derived from the reflog, and if it can't find the information in the reflog, it instead shows the generic "Not currently on any branch" (which is the equivalent of the "(detached HEAD)" you see in "git worktree list").

Each worktree has its own newly-created reflog, which does _not_ contain enough information for 'git status' to present the more detailed "detached" message, thus it falls back to the generic one. Perhaps seeding the worktree's reflog with a bit more information at creation time would be a good #leftoverbits task.