[PATCH 5/6] completion: list existing working trees for 'git worktree' subcommands

["SZEDER Gábor" <szeder.dev@gmail.com>]

Complete the paths of existing working trees for 'git worktree's
'move', 'remove', 'lock', and 'unlock' subcommands.

Note that 'git worktree list --porcelain' shows absolute paths, so for
simplicity's sake we'll complete full absolute paths as well (as
opposed to turning them into relative paths by finding common leading
directories between $PWD and the working tree's path and removing
them, risking trouble with symbolic links or Windows drive letters; or
completing them one path component at a time).

Never list the path of the main working tree, as it cannot be moved,
removed, locked, or unlocked.

Arguably 'git worktree unlock <TAB>' should only complete locked
working trees, but 'git worktree list --porcelain' doesn't indicate
which working trees are locked.  So for now it will complete the paths
of all existing working trees, including non-locked ones as well.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
---
 contrib/completion/git-completion.bash | 28 +++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 643272eb2f..4eb13b06d6 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -2981,10 +2981,21 @@ _git_whatchanged ()
 	_git_log
 }
 
+__git_complete_worktree_paths ()
+{
+	local IFS=$'\n'
+	__gitcomp_nl "$(git worktree list --porcelain |
+		sed -n -e '2,$ s/^worktree //p')"
+}
+
 _git_worktree ()
 {
 	local subcommands="add list lock move prune remove unlock"
-	local subcommand="$(__git_find_on_cmdline "$subcommands")"
+	local subcommand subcommand_idx
+
+	subcommand="$(__git_find_on_cmdline --show-idx "$subcommands")"
+	subcommand_idx="${subcommand% *}"
+	subcommand="${subcommand#* }"
 
 	case "$subcommand,$cur" in
 	,*)
@@ -2993,6 +3004,21 @@ _git_worktree ()
 	*,--*)
 		__gitcomp_builtin worktree_$subcommand
 		;;
+	lock,*|remove,*|unlock,*)
+		__git_complete_worktree_paths
+		;;
+	move,*)
+		if [ $cword -eq $((subcommand_idx+1)) ]; then
+			# The first parameter must be an existing working
+			# tree to be moved.
+			__git_complete_worktree_paths
+		else
+			# The second parameter is the destination: it could
+			# be any path, so don't list anything, but let Bash
+			# fall back to filename completion.
+			:
+		fi
+		;;
 	esac
 }
 
-- 
2.23.0.1084.gae250eaa40