[PATCH v5 2/8] worktree: add `relativeWorktrees` extension

[Caleb White <cdwhite3@pm.me>]

A new extension, `relativeWorktrees`, is added to indicate that at least
one worktree in the repository has been linked with relative paths.
This ensures older Git versions do not attempt to automatically prune
worktrees with relative paths, as they would not not recognize the
paths as being valid.

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Caleb White <cdwhite3@pm.me>
---
 Documentation/config/extensions.txt | 6 ++++++
 repository.c                        | 1 +
 repository.h                        | 1 +
 setup.c                             | 7 +++++++
 setup.h                             | 1 +
 5 files changed, 16 insertions(+)

diff --git a/Documentation/config/extensions.txt b/Documentation/config/extensions.txt
index 5dc569d1c9c77c15e32441493289f9c9dd5e7f0b..5cb4721a0e0ae1ed64f90492c0dc18b96473cb33 100644
--- a/Documentation/config/extensions.txt
+++ b/Documentation/config/extensions.txt
@@ -63,6 +63,12 @@ Note that this setting should only be set by linkgit:git-init[1] or
 linkgit:git-clone[1]. Trying to change it after initialization will not
 work and will produce hard-to-diagnose issues.
 
+relativeWorktrees::
+	If enabled, indicates at least one worktree has been linked with
+	relative paths. Automatically set if a worktree has been created or
+	repaired with either the `--relative-paths` option or with the
+	`worktree.useRelativePaths` config set to `true`.
+
 worktreeConfig::
 	If enabled, then worktrees will load config settings from the
 	`$GIT_DIR/config.worktree` file in addition to the
diff --git a/repository.c b/repository.c
index f988b8ae68a6a29792e7f2c980a02bd0e388a3b9..1a6a62bbd03a5dc4fdade3eb45ea2696968abc23 100644
--- a/repository.c
+++ b/repository.c
@@ -283,6 +283,7 @@ int repo_init(struct repository *repo,
 	repo_set_compat_hash_algo(repo, format.compat_hash_algo);
 	repo_set_ref_storage_format(repo, format.ref_storage_format);
 	repo->repository_format_worktree_config = format.worktree_config;
+	repo->repository_format_relative_worktrees = format.relative_worktrees;
 
 	/* take ownership of format.partial_clone */
 	repo->repository_format_partial_clone = format.partial_clone;
diff --git a/repository.h b/repository.h
index 24a66a496a6ff516ce06d47b7329b3d36eb701ca..c4c92b2ab9c9e3b425dc2974636e33d1f4089c69 100644
--- a/repository.h
+++ b/repository.h
@@ -150,6 +150,7 @@ struct repository {
 
 	/* Configurations */
 	int repository_format_worktree_config;
+	int repository_format_relative_worktrees;
 
 	/* Indicate if a repository has a different 'commondir' from 'gitdir' */
 	unsigned different_commondir:1;
diff --git a/setup.c b/setup.c
index 1e5c2eacb19eb6b230d7c9954f66fc7ae0b05631..39ff48d9dc5d67b16159c6cca66ff2663bbba6cf 100644
--- a/setup.c
+++ b/setup.c
@@ -683,6 +683,9 @@ static enum extension_result handle_extension(const char *var,
 				     "extensions.refstorage", value);
 		data->ref_storage_format = format;
 		return EXTENSION_OK;
+	} else if (!strcmp(ext, "relativeworktrees")) {
+		data->relative_worktrees = git_config_bool(var, value);
+		return EXTENSION_OK;
 	}
 	return EXTENSION_UNKNOWN;
 }
@@ -1854,6 +1857,8 @@ const char *setup_git_directory_gently(int *nongit_ok)
 						    repo_fmt.ref_storage_format);
 			the_repository->repository_format_worktree_config =
 				repo_fmt.worktree_config;
+			the_repository->repository_format_relative_worktrees =
+				repo_fmt.relative_worktrees;
 			/* take ownership of repo_fmt.partial_clone */
 			the_repository->repository_format_partial_clone =
 				repo_fmt.partial_clone;
@@ -1950,6 +1955,8 @@ void check_repository_format(struct repository_format *fmt)
 				    fmt->ref_storage_format);
 	the_repository->repository_format_worktree_config =
 		fmt->worktree_config;
+	the_repository->repository_format_relative_worktrees =
+		fmt->relative_worktrees;
 	the_repository->repository_format_partial_clone =
 		xstrdup_or_null(fmt->partial_clone);
 	clear_repository_format(&repo_fmt);
diff --git a/setup.h b/setup.h
index e496ab3e4de580c2d9f95a7ea0eaf90e0d41b070..18dc3b73686ce28fac2fe04282ce95f8bf3e6b74 100644
--- a/setup.h
+++ b/setup.h
@@ -129,6 +129,7 @@ struct repository_format {
 	int precious_objects;
 	char *partial_clone; /* value of extensions.partialclone */
 	int worktree_config;
+	int relative_worktrees;
 	int is_bare;
 	int hash_algo;
 	int compat_hash_algo;

-- 
2.47.0