Re: [PATCH 1/1] branch: advise the user to checkout a different branch before deleting

[Eric Sunshine <sunshine@sunshineco.com>]

On Wed, Jan 1, 2020 at 9:50 PM Heba Waly via GitGitGadget
<gitgitgadget@gmail.com> wrote:
> Display a hint to the user when attempting to delete a checked out
> branch saying "Checkout another branch before deleting this one:
> git checkout <branch_name>".
>
> Currently the user gets an error message saying: "error: Cannot delete
> branch <branch_name> checked out at <path>". The hint will be displayed
> after the error message.
>
> Signed-off-by: Heba Waly <heba.waly@gmail.com>
> ---
> diff --git a/builtin/branch.c b/builtin/branch.c
> @@ -240,6 +240,8 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
>                                 error(_("Cannot delete branch '%s' "
>                                         "checked out at '%s'"),
>                                       bname.buf, wt->path);
> +                               advise(_("Checkout another branch before deleting this "
> +                                                "one: git checkout <branch_name>"));

s/another/a different/ would make the meaning clearer.

Let's try to avoid underscores in placeholders. <branch-name> would be
better, however, git-checkout documentation just calls this <branch>,
so that's probably a good choice.

However, these days, I think we're promoting git-switch rather than
git-checkout, so perhaps this advice should follow suit.

Finally, is this advice sufficient for newcomers when the branch the
user is trying to delete is in fact checked out in a worktree other
than the worktree in which the git-branch command is being invoked?
That is:

    $ pwd
    /home/me/foo
    $ git branch -D bip
    Cannot delete  branch 'bip' checked out at '/home/me/bar'
    hint: Checkout another branch before deleting this one:
    hint: git checkout <branch>
    $ git checkout master # user follows advice
    $ git branch -D bip
    Cannot delete  branch 'bip' checked out at '/home/me/foo'
    hint: Checkout another branch before deleting this one:
    hint: git checkout <branch>
    $

And the user is left scratching his or her head wondering why
git-branch is still showing the error despite following the
instructions in the hint.

> diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
> @@ -808,7 +808,8 @@ test_expect_success 'test deleting branch without config' '
>  test_expect_success 'deleting currently checked out branch fails' '
>         git worktree add -b my7 my7 &&
>         test_must_fail git -C my7 branch -d my7 &&
> -       test_must_fail git branch -d my7 &&
> +       test_must_fail git branch -d my7 >actual.out 2>actual.err &&
> +       test_i18ngrep "hint: Checkout another branch" actual.err &&

Why does this capture standard output into 'actual.out' if that file
is never consulted?

>         rm -r my7 &&
>         git worktree prune
>  '