Re: [PATCH v2 2/4] introduce submodule.superprojectGitDir cache
From: Junio C Hamano <hidden>
Date: 2021-06-16 04:40:58
Emily Shaffer [off-list ref] writes:
quoted hunk
Teach submodules a reference to their superproject's gitdir. This allows us to A) know that we're running from a submodule, and B) have a shortcut to the superproject's vitals, for example, configs. By using a relative path instead of an absolute path, we can move the superproject directory around on the filesystem without breaking the submodule's cache. Since this cached value is only introduced during new submodule creation via `git submodule add`, though, there is more work to do to allow the cache to be created at other times. Signed-off-by: Emily Shaffer <redacted> --- Documentation/config/submodule.txt | 12 +++++++++ builtin/submodule--helper.c | 4 +++ t/t7400-submodule-basic.sh | 40 ++++++++++++++++-------------- 3 files changed, 38 insertions(+), 18 deletions(-)diff --git a/Documentation/config/submodule.txt b/Documentation/config/submodule.txt index d7a63c8c12..7c459cc19e 100644 --- a/Documentation/config/submodule.txt +++ b/Documentation/config/submodule.txt@@ -90,3 +90,15 @@ submodule.alternateErrorStrategy:: `ignore`, `info`, `die`. Default is `die`. Note that if set to `ignore` or `info`, and if there is an error with the computed alternate, the clone proceeds as if no alternate was specified. + +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. 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. Thanks.