if multi && len(rest) != 0 {
				return nil, errors.New("{...} wildcard not at end")
			}
			if name == "" {
				return nil, errors.New("empty wildcard")
			}
			if !isValidWildcardName(name) {
				return nil, fmt.Errorf("bad wildcard name %q", name)
			}
			if seenNames[name] {
				return nil, fmt.Errorf("duplicate wildcard name %q", name)
			}
			seenNames[name] = true