preg_match and preg_match_all both do not set $matches on regex fail, leaving as it was set prior to call

Description

The following code:

<?php // preg_match_all.php
$matches = [0 => 'Orange',
            1 => 'Apple',
            2 => 'Banana',
            3 => 'Monkey'];
$result = preg_match_all('aeiou{0,', 'ou', $matches);
var_dump($result);
var_dump($matches);

$result = preg_match('aeiou{0,', 'ou', $matches);
var_dump($result);
var_dump($matches);

Resulted in this output from command line %php preg_match_all.php:

PHP Warning:  preg_match_all(): Delimiter must not be alphanumeric or backslash in preg_match_all.php on line 6
PHP Stack trace:
PHP   1. {main}() preg_match_all.php:0
PHP   2. preg_match_all($pattern = 'aeiou{0,', $subject = 'ou', $subpatterns = [0 => 'Orange', 1 => 'Apple', 2 => 'Banana', 3 => 'Monkey']) preg_match_all.php:6
preg_match_all.php:7:
bool(false)
preg_match_all.php:8:
array(4) {
    [0] =>
  string(6) "Orange"
    [1] =>
  string(5) "Apple"
    [2] =>
  string(6) "Banana"
    [3] =>
  string(6) "Monkey"
}
PHP Warning:  preg_match(): Delimiter must not be alphanumeric or backslash in preg_match_all.php on line 10
PHP Stack trace:
PHP   1. {main}() preg_match_all.php:0
PHP   2. preg_match($pattern = 'aeiou{0,', $subject = 'ou', $subpatterns = [0 => 'Orange', 1 => 'Apple', 2 => 'Banana', 3 => 'Monkey']) preg_match_all.php:10
preg_match_all.php:11:
bool(false)
preg_match_all.php:12:
array(4) {
    [0] =>
  string(6) "Orange"
    [1] =>
  string(5) "Apple"
    [2] =>
  string(6) "Banana"
    [3] =>
  string(6) "Monkey"
}

But I expected this output instead:

PHP Warning:  preg_match_all(): Delimiter must not be alphanumeric or backslash in preg_match_all.php on line 6
PHP Stack trace:
PHP   1. {main}() preg_match_all.php:0
PHP   2. preg_match_all($pattern = 'aeiou{0,', $subject = 'ou', $subpatterns = [0 => 'Orange', 1 => 'Apple', 2 => 'Banana', 3 => 'Monkey']) preg_match_all.php:6
preg_match_all.php:7:
bool(false)
preg_match_all.php:8:
either: null or array[0]
PHP Warning:  preg_match(): Delimiter must not be alphanumeric or backslash in preg_match_all.php on line 10
PHP Stack trace:
PHP   1. {main}() preg_match_all.php:0
PHP   2. preg_match($pattern = 'aeiou{0,', $subject = 'ou', $subpatterns = [0 => 'Orange', 1 => 'Apple', 2 => 'Banana', 3 => 'Monkey']) preg_match_all.php:10
preg_match_all.php:11:
bool(false)
preg_match_all.php:12:
either: null or array[0]

PHP Version

PHP 7.4.27

Operating System

No response

提供された preg_match() と preg_match_all() の呼び出しを、無効なパターンを使って PHP 7.4.27 で再現し、その後 PHP インタープリター内で 2 つの API を追跡します。完了条件は、マッチに失敗した場合に呼び出し元の以前の $matches の内容がそのまま残らなくなり、両方の関数に対するリグレッションテストのカバレッジがあることです。