Xor operation on strings on PHP 7.x is viewed as conversion to int

[nach-code]

PHP allows strings to be xor'd. From: https://www.php.net/manual/en/language.operators.bitwise.php

If both operands for the &, | and ^ operators are strings, then the operation will be performed on the ASCII values of the characters that make up the strings and the result will be a string. In all other cases, both operands will be converted to integers and the result will be an integer.

However, when this is done, PHPStan on PHP 7.x now thinks the string has been converted into an integer.

https://phpstan.org/r/12e63cdd-d516-4db2-a314-51da4f5c3101

The output should not have errors here, but PHPStan thinks that the string is now an int, that cannot be passed to base64_encode: Parameter #1 $str of function base64_encode expects string, int given.

[staabm]

Relevant code is https://github.com/phpstan/phpstan-src/blob/d0207ed79e94e4b4daceb0f83abb1f481ee3250b/src/Reflection/InitializerExprTypeResolver.php#L619