`zend_memnistr` results are incorrect under certain conditions

[SakiTakamachi]

Description

The following code:

<?php
var_dump(stripos('aaBBBBBbb', 'b'));

Resulted in this output:

int(7)

But I expected this output instead:

int(2)

This occurs when the following conditions are met:

• $needle is single character
• (Number of characters from the first lowercase letter to the end) >= (Number of characters from the beginning to the first uppercase letter)
• Uppercase letters appear before lowercase letters

PHP Version

PHP8.2+

Operating System

any

[SakiTakamachi]

As you know, this affects stripos() and stristr().

The master branch uses php_memnistr in the curl options set, but since needle is not a single character, it is not affected.