[PATCH v2 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.

Ideally we would only list unlocked working trees for the 'move',
'remove', and 'lock' subcommands, and only locked ones for 'unlock'.
Alas, 'git worktree list --porcelain' doesn't indicate which working
trees are locked, so for now we'll complete the paths of all existing
working trees.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
---
 contrib/completion/git-completion.bash | 30 +++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 643272eb2f..5eae0bfd18 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -2981,10 +2981,23 @@ _git_whatchanged ()
 	_git_log
 }
 
+__git_complete_worktree_paths ()
+{
+	local IFS=$'\n'
+	__gitcomp_nl "$(git worktree list --porcelain |
+		# Skip the first entry: it's the path of the main worktree,
+		# which can't be moved, removed, locked, etc.
+		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 +3006,21 @@ _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
 }
 
-- 
2.24.1.982.ga4d4aba446