`zend_extension` php.ini uses different path discovery than `extension`

Description

Steps to reproduce:

File structure:

• ./ - current directory
• ./php-8.1.12-nts-Win32-vs16-x64 - extracted from official Windows download
• ./php-8.1.12-nts-Win32-vs16-x64\ext\php_xdebug.dll - downloaded from official xdebug website

When I run .\php-8.1.12-nts-Win32-vs16-x64\php.exe -d xdebug.mode=coverage -d extension=ext/php_xdebug test.php I get:

Warning: Xdebug MUST be loaded as a Zend extension in Unknown on line 0
... (xdebug is working, output from test.php code)

When I run .\php-8.1.12-nts-Win32-vs16-x64\php.exe -d xdebug.mode=coverage -d zend_extension=ext/php_xdebug.dll test.php I get:

Warning: Failed loading Zend extension 'ext/php_xdebug.dll' (tried: C:\php\ext\ext/php_xdebug.dll (The specified module could not be found), C:\php\ext\php_ext/php_xdebug.dll.dll (The specified module could not be found)) in Unknown on line 0

Fatal error: Uncaught Error: Call to undefined function xdebug_start_code_coverage() in C:\Users\mvorisek\Desktop\forks\cov-php81-debug\test.php:5
Stack trace:
#0 {main}
  thrown in C:\Users\mvorisek\Desktop\forks\cov-php81-debug\test.php on line 5

I would expect exactly the same extension discovery for extension and zend_extension.

(and I can confirm zend_extension with absolute php_xdebug.dll path is working)

PHP Version

PHP 8.1.12 NTS Win x64

Operating System

Windows 10

まず、PHP 8.1.12 NTS ビルドに対して 2 つの Windows コマンドラインを再現し、extension と zend_extension の相対パスの扱いを比較します。拡張機能の読み込みエントリポイントとそのパス解決動作を追跡します。完了の条件は、絶対パスの動作を変更せずに、両方のディレクティブが同じ相対 DLL パスを見つけることです。