[PATCH 3/3] git-checkout.txt: a note about multiple checkout support for submodules

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

The goal seems to be using multiple checkouts to reduce disk space.
But we have not reached an agreement how things should be. There are a
couple options.

 - You may want to keep $SUB repos elsewhere (perhaps in a central
   place) outside $SUPER. This is also true for nested submodules
   where a superproject may be a submodule of another superproject.

 - You may want to keep all $SUB repos in $SUPER/modules (or some
   other place in $SUPER)

 - We could even push it further and merge all $SUB repos into $SUPER
   instead of storing them separately. But that would at least require
   ref namespace enabled.

On top of that, git-submodule.sh expects $GIT_DIR/config to be
per-worktree, at least for the submodule.* part. Here I think we have
two options, either update config.c to also read
$GIT_DIR/config.worktree (which is per worktree) in addition to
$GIT_DIR/config (shared) and store worktree-specific vars in the new
place, or update git-submodule.sh to read/write submodule.* directly
from $GIT_DIR/config.submodule (per worktree).

These take time to address properly. Meanwhile, make a note to the
user that they should not use multiple worktrees in submodule context.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/git-checkout.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 52eaa48..72def5b 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -463,6 +463,9 @@ to `/path/main/.git/worktrees/test-next` then a file named
 `test-next` entry from being pruned.  See
 linkgit:gitrepository-layout[5] for details.
 
+Multiple checkout support for submodules is incomplete. It is NOT
+recommended to make multiple checkouts of a superproject.
+
 EXAMPLES
 --------
 
-- 
2.2.0.84.ge9c7a8a