list,unshare: dissalow -r without path

config.go

@@ -32,7 +32,7 @@ type pathConfig struct {
 // optPathConfig is like pathConfig, but the Path is optional.
 // If Path is empty, it looks for a single account to match.
 type optPathConfig struct {
-	Path string `arg:"" optional:"" help:"file on local filesystem. Empty matches all files,xor=opath"`
+	Path string `arg:"" optional:"" help:"file on local filesystem. Empty matches all files"`
 	account
 	remoteFile string
 	accounts   []account

list.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"net/url"
 	"os"
@@ -12,13 +13,20 @@ import (
 type list struct {
 	optPathConfig
 
-	Recursive bool `kong:"short=r,help='recursively descend into folders',xor=opath"`
+	Recursive bool `kong:"short=r,help='recursively descend into folders'"`
 }
 
 func isSubfile(dir, f string) bool {
 	return dir == "/" || dir == f || strings.HasPrefix(f, dir+"/")
 }
 
+func (l *list) AfterApply() error {
+	if l.Path == "" && l.Recursive {
+		return errors.New("omitted path matches all shares, --recursive (-r) is unnecessary")
+	}
+	return nil
+}
+
 func (l *list) Run() error {
 	accounts := l.accounts
 	if l.remoteFile != "" {