Re: [PATCH v2 2/4] introduce submodule.superprojectGitDir cache

On Wed, Jun 16, 2021 at 01:40:36PM +0900, Junio C Hamano wrote:

Emily Shaffer [off-list ref] writes:

quoted

+submodule.superprojectGitDir::
+	The relative path from the submodule's worktree  to the superproject's
+	gitdir. This config should only be present in projects which are
+	submodules, but is not guaranteed to be present in every submodule. It
+	is set automatically during submodule creation.
++
+	In situations where more than one superproject references the same
+	submodule worktree, the value of this config and the behavior of
+	operations which use it are undefined. To reference a single project
+	from multiple superprojects, it is better to create a worktree of the
+	submodule for each superproject.

You'd need to dedent the second paragraph that follows a lone '+'
sign to typeset this correctly.

Ok.

The new paragraph suggests separate worktrees for the same submodule
repository, but for that to work correctly,

 - "git clone [--recurse-submodules]" that clones the second
   superproject that shares the same submodule with a superproject
   that we already locally has to support a way for users to tell
   where to grab that existing submodule from and arrange a new
   worktree, instead of creating another instance of the submodule
   repository by cloning it afresh.

 - The "submodule.superprojectGitDir" needs to be set to
   per-worktree half of the repo-local configuration file.

Because I usually do not pay much attention to the submodule part of
the toolset, I may well be mistaken, but I suspect that the former
does not exist yet.  If I recall correctly, the latter was a NEEDSWORK
item in the previous round of this patchset?

As I said, I think it is OK for now to stop at declaring that you
cannot simply do it without hinting something that may not fully
work.

Yeah, that is all correct. Ok, I will drop the broken suggestion.

 - Emily