Can't understand mount point directories on Windows

Description

The following code:

<?php
var_dump(getcwd());
print_r(scandir("."));

Resulted in this output:

string(16) "R:\dreamflame.in"
PHP Warning:  scandir(.): The system cannot find the path specifi (code: 3) in Command line code on line 2

Warning: scandir(.): The system cannot find the path specifi (code: 3) in Command line code on line 2
PHP Warning:  scandir(.): Failed to open directory: No such file or directory in Command line code on line 2

Warning: scandir(.): Failed to open directory: No such file or directory in Command line code on line 2
PHP Warning:  scandir(): (errno 2): No such file or directory in Command line code on line 2

Warning: scandir(): (errno 2): No such file or directory in Command line code on line 2

But I expected directory listing instead

PHP Version

PHP 8.0.12

Operating System

Windows 11 build 22000

まず、報告されたパス R:\dreamflame.in を使用し、Windows 11 上の PHP 8.0.12 で、提供された getcwd() と scandir(".") の例を再現します。カレントディレクトリとディレクトリ一覧の動作を通常のディレクトリと比較します。scandir(".") が警告なしに期待される内容を一覧表示すれば完了です。