Re: Regression: submodule worktrees can clobber core.worktree config

From: Stefan Beller <sbeller@google.com>
Date: Jan 9, 2019, 17:42 UTC
Message-ID: <CAGZ79kZBwocC=UzjW+DxodwJkQZ2mNMYNjsk6sL4SCqdhGoQ7w@mail.gmail.com>
In-Reply-To: <CAG0vfyQeA3Hm7AsYgYtP4v-Yg0=rKXW0YYfg_emAwEscZha4VA@mail.gmail.com>

On Tue, Jan 8, 2019 at 2:16 PM Tomasz Śniatowski <tsniatowski@vewd.com> wrote:

Show 24 quoted lines

>
> After upgrading to 2.20.1 I noticed in some submodule+worktree scenarios git
> will break the submodule configuration. Reproducible with:
>     git init a && (cd a; touch a; git add a; git commit -ma)
>     git init b && (cd b; git submodule add ../a; git commit -mb)
>     git -C b worktree add ../b2
>     git -C b/a worktree add ../../b2/a
>     git -C b status
>     git -C b2 submodule update
>     git -C b status
>
> The submodule update in the _worktree_ puts an invalid core.worktree value in
> the _original_ repository submodule config (b/.git/modules/a/config), causing
> the last git status to error out with:
>     fatal: cannot chdir to '../../../../../../b2/a': No such file or directory
>     fatal: 'git status --porcelain=2' failed in submodule a
>
> Looking at the config file itself, the submodule update operation applies the
> following change (the new path is invalid):
>     -       worktree = ../../../a
>     +       worktree = ../../../../../../b2/a
>
> This worked fine on 2.19.2 (no config change, no error), and was useful to have
> a worktree with (large) submodules that are also worktrees.

Thanks for reporting the issue!

>
> Bisects down to:
> 74d4731da1 submodule--helper: replace connect-gitdir-workingtree by
> ensure-core-worktree

So this would need to update the worktree config, not the generic config.

We'd need to replace the line
    cfg_file = repo_git_path(&subrepo, "config");
in builtin/submodule--helper.c::ensure_core_worktree()
to be a worktree specific call.

Or the other way round we'd want to make repo_git_path to be worktree specific and introduce repo_common_path for the main working tree.

Looking at Duys tree, https://gitlab.com/pclouds/git/commit/94751ada7c32eb6fb2c67dd7723161d1955a5683 is pretty much what we need.

Reverting that topic that introduced this (4d6d6e, Merge branch 'sb/submodule-update-in-c'), might be possible but that would conflict with another followup that fixes issues in that series (see sb/submodule-unset-core-worktree-when-worktree-is-lost https://github.com/gitster/git/commits/sb/submodule-unset-core-worktree-when-worktree-is-lost) so I'd rather just cherry-pick the commit from Duy.

Stefan