worktree remove: new command

This command allows to delete a worktree. Like 'move' you cannot
remove the main worktree, or one with submodules inside [1].

For deleting $GIT_WORK_TREE, Untracked files or any staged entries are
considered precious and therefore prevent removal by default. Ignored
files are not precious.

When it comes to deleting $GIT_DIR, there's no "clean" check because
there should not be any valuable data in there, except:

- HEAD reflog. There is nothing we can do about this until somebody
  steps up and implements the ref graveyard.

- Detached HEAD. Technically it can still be recovered. Although it
  may be nice to warn about orphan commits like 'git checkout' does.

[1] We do 'git status' with --ignore-submodules=all for safety
    anyway. But this needs a closer look by submodule people before we
    can allow deletion. For example, if a submodule is totally clean,
    but its repo not absorbed to the main .git dir, then deleting
    worktree also deletes the valuable .submodule repo too.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

4 files changed, 179 insertions, 11 deletions

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index e6764ee8e0..d322acbc67 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -14,6 +14,7 @@ SYNOPSIS
 'git worktree lock' [--reason <string>] <worktree>
 'git worktree move' <worktree> <new-path>
 'git worktree prune' [-n] [-v] [--expire <expire>]
+'git worktree remove' [--force] <worktree>
 'git worktree unlock' <worktree>
 
 DESCRIPTION
@@ -85,6 +86,13 @@ prune::
 
 Prune working tree information in $GIT_DIR/worktrees.
 
+remove::
+
+Remove a working tree. Only clean working trees (no untracked files
+and no modification in tracked files) can be removed. Unclean working
+trees or ones with submodules can be removed with `--force`. The main
+working tree cannot be removed.
+
 unlock::
 
 Unlock a working tree, allowing it to be pruned, moved or deleted.
@@ -94,9 +102,10 @@ OPTIONS
 
 -f::
 --force::
-	By default, `add` refuses to create a new working tree when `<commit-ish>` is a branch name and
-	is already checked out by another working tree. This option overrides
-	that safeguard.
+	By default, `add` refuses to create a new working tree when
+	`<commit-ish>` is a branch name and is already checked out by
+	another working tree and `remove` refuses to remove an unclean
+	working tree. This option overrides that safeguard.
 
 -b <new-branch>::
 -B <new-branch>::
@@ -278,12 +287,6 @@ Multiple checkout in general is still experimental, and the support
 for submodules is incomplete. It is NOT recommended to make multiple
 checkouts of a superproject.
 
-git-worktree could provide more automation for tasks currently
-performed manually, such as:
-
-- `remove` to remove a linked working tree and its administrative files (and
-  warn if the working tree is dirty)
-
 GIT
 ---
 Part of the linkgit:git[1] suite
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 4789cebe11..990e47b315 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -19,6 +19,7 @@ static const char * const worktree_usage[] = {
 	N_("git worktree lock [<options>] <path>"),
 	N_("git worktree move <worktree> <new-path>"),
 	N_("git worktree prune [<options>]"),
+	N_("git worktree remove [<options>] <worktree>"),
 	N_("git worktree unlock <path>"),
 	NULL
 };
@@ -624,7 +625,7 @@ static void validate_no_submodules(const struct worktree *wt)
 	discard_index(&istate);
 
 	if (found_submodules)
-		die(_("working trees containing submodules cannot be moved"));
+		die(_("working trees containing submodules cannot be moved or removed"));
 }
 
 static int move_worktree(int ac, const char **av, const char *prefix)
@@ -688,6 +689,135 @@ static int move_worktree(int ac, const char **av, const char *prefix)
 	return 0;
 }
 
+/*
+ * Note, "git status --porcelain" is used to determine if it's safe to
+ * delete a whole worktree. "git status" does not ignore user
+ * configuration, so if a normal "git status" shows "clean" for the
+ * user, then it's ok to remove it.
+ *
+ * This assumption may be a bad one. We may want to ignore
+ * (potentially bad) user settings and only delete a worktree when
+ * it's absolutely safe to do so from _our_ point of view because we
+ * know better.
+ */
+static void check_clean_worktree(struct worktree *wt,
+				 const char *original_path)
+{
+	struct argv_array child_env = ARGV_ARRAY_INIT;
+	struct child_process cp;
+	char buf[1];
+	int ret;
+
+	/*
+	 * Until we sort this out, all submodules are "dirty" and
+	 * will abort this function.
+	 */
+	validate_no_submodules(wt);
+
+	argv_array_pushf(&child_env, "%s=%s/.git",
+			 GIT_DIR_ENVIRONMENT, wt->path);
+	argv_array_pushf(&child_env, "%s=%s",
+			 GIT_WORK_TREE_ENVIRONMENT, wt->path);
+	memset(&cp, 0, sizeof(cp));
+	argv_array_pushl(&cp.args, "status",
+			 "--porcelain", "--ignore-submodules=none",
+			 NULL);
+	cp.env = child_env.argv;
+	cp.git_cmd = 1;
+	cp.dir = wt->path;
+	cp.out = -1;
+	ret = start_command(&cp);
+	if (ret)
+		die_errno(_("failed to run 'git status' on '%s'"),
+			  original_path);
+	ret = xread(cp.out, buf, sizeof(buf));
+	if (ret)
+		die(_("'%s' is dirty, use --force to delete it"),
+		    original_path);
+	close(cp.out);
+	ret = finish_command(&cp);
+	if (ret)
+		die_errno(_("failed to run 'git status' on '%s', code %d"),
+			  original_path, ret);
+}
+
+static int delete_git_work_tree(struct worktree *wt)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int ret = 0;
+
+	strbuf_addstr(&sb, wt->path);
+	if (remove_dir_recursively(&sb, 0)) {
+		error_errno(_("failed to delete '%s'"), sb.buf);
+		ret = -1;
+	}
+	strbuf_release(&sb);
+	return ret;
+}
+
+static int delete_git_dir(struct worktree *wt)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int ret = 0;
+
+	strbuf_addstr(&sb, git_common_path("worktrees/%s", wt->id));
+	if (remove_dir_recursively(&sb, 0)) {
+		error_errno(_("failed to delete '%s'"), sb.buf);
+		ret = -1;
+	}
+	strbuf_release(&sb);
+	return ret;
+}
+
+static int remove_worktree(int ac, const char **av, const char *prefix)
+{
+	int force = 0;
+	struct option options[] = {
+		OPT_BOOL(0, "force", &force,
+			 N_("force removing even if the worktree is dirty")),
+		OPT_END()
+	};
+	struct worktree **worktrees, *wt;
+	struct strbuf errmsg = STRBUF_INIT;
+	const char *reason;
+	int ret = 0;
+
+	ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
+	if (ac != 1)
+		usage_with_options(worktree_usage, options);
+
+	worktrees = get_worktrees(0);
+	wt = find_worktree(worktrees, prefix, av[0]);
+	if (!wt)
+		die(_("'%s' is not a working tree"), av[0]);
+	if (is_main_worktree(wt))
+		die(_("'%s' is a main working tree"), av[0]);
+	reason = is_worktree_locked(wt);
+	if (reason) {
+		if (*reason)
+			die(_("cannot remove a locked working tree, lock reason: %s"),
+			    reason);
+		die(_("cannot remove a locked working tree"));
+	}
+	if (validate_worktree(wt, &errmsg))
+		die(_("validation failed, cannot remove working tree: %s"),
+		    errmsg.buf);
+	strbuf_release(&errmsg);
+
+	if (!force)
+		check_clean_worktree(wt, av[0]);
+
+	ret |= delete_git_work_tree(wt);
+	/*
+	 * continue on even if ret is non-zero, there's no going back
+	 * from here.
+	 */
+	ret |= delete_git_dir(wt);
+
+	free_worktrees(worktrees);
+	return ret;
+}
+
 int cmd_worktree(int ac, const char **av, const char *prefix)
 {
 	struct option options[] = {
@@ -712,5 +842,7 @@ int cmd_worktree(int ac, const char **av, const char *prefix)
 		return unlock_worktree(ac - 1, av + 1, prefix);
 	if (!strcmp(av[1], "move"))
 		return move_worktree(ac - 1, av + 1, prefix);
+	if (!strcmp(av[1], "remove"))
+		return remove_worktree(ac - 1, av + 1, prefix);
 	usage_with_options(worktree_usage, options);
 }
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index b87d387686..ff4a39631e 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -3087,7 +3087,7 @@ _git_whatchanged ()
 
 _git_worktree ()
 {
-	local subcommands="add list lock move prune unlock"
+	local subcommands="add list lock move prune remove unlock"
 	local subcommand="$(__git_find_on_cmdline "$subcommands")"
 	if [ -z "$subcommand" ]; then
 		__gitcomp "$subcommands"
@@ -3105,6 +3105,9 @@ _git_worktree ()
 		prune,--*)
 			__gitcomp "--dry-run --expire --verbose"
 			;;
+		remove,--*)
+			__gitcomp "--force"
+			;;
 		*)
 			;;
 		esac
diff --git a/t/t2028-worktree-move.sh b/t/t2028-worktree-move.sh
index deb486cd8e..4718c4552f 100755
--- a/t/t2028-worktree-move.sh
+++ b/t/t2028-worktree-move.sh
@@ -96,4 +96,34 @@ test_expect_success 'move worktree to another dir' '
 	test_cmp expected2 actual2
 '
 
+test_expect_success 'remove main worktree' '
+	test_must_fail git worktree remove .
+'
+
+test_expect_success 'move some-dir/destination back' '
+	git worktree move some-dir/destination destination
+'
+
+test_expect_success 'remove locked worktree' '
+	git worktree lock destination &&
+	test_when_finished "git worktree unlock destination" &&
+	test_must_fail git worktree remove destination
+'
+
+test_expect_success 'remove worktree with dirty tracked file' '
+	echo dirty >>destination/init.t &&
+	test_when_finished "git -C destination checkout init.t" &&
+	test_must_fail git worktree remove destination
+'
+
+test_expect_success 'remove worktree with untracked file' '
+	: >destination/untracked &&
+	test_must_fail git worktree remove destination
+'
+
+test_expect_success 'force remove worktree with untracked file' '
+	git worktree remove --force destination &&
+	test_path_is_missing destination
+'
+
 test_done