Update comments.inc.php for compatibility with PHP 8.3

[qbi]

When you want to access all comments, S9Y runs into an HTTP 500: PHP Fatal error: Uncaught DivisionByZeroError: Division by zero in line 260.

The comparison of strings and integers has changed in PHP 8. See https://www.php.net/manual/en/migration80.incompatible.php

Previously the comparison in line 260 was 0 == 'all' -> true. Whith the changes the comparison now is 0 == 'all' -> false. Which leads to the above mentioned error message.

I changed the code in a way that $commentsPerPage has either an interger orCOMMENTS_FILTER_ALL as value and the comparison now checks type and value. So in the case of all comments the comparison is 'all' === 'all -> true.

This should fix the code.

[mattsches]

Thank you, good catch and good fix!

My suggestion would be to change the first section as follows.
This introduces a stricter (type-safe) check against COMMENTS_FILTER_ALL.

if ($commentsPerPage !== COMMENTS_FILTER_ALL) {
    $commentsPerPage = (int)$commentsPerPage;
}

What do you think?

[onli]

Surprisingly complicated code, originally. I assume it was never intended to rely on 0 == 'all' being true, but rather it was missed that the comparison was strange.

Alternative fix would be to always cast COMMENTS_FILTER_ALL when used in the comparison, so also on line 260 and 274, like

$pages = ($commentsPerPage == (int)COMMENTS_FILTER_ALL ? 1 : ceil($totalComments/(int)$commentsPerPage));

Then this becomes a 0 == 0 when $serendipity['GET']['filter']['perpage'] was set to COMMENTS_FILTER_ALL (which will be a string like 'all', and casts to 0)

Not sure that's better, but wanted to understand the bug and have this shared :)

[onli]

I prepared the NEWS entry for this change. @qbi, please let us know if this is the way you want to be credited, or under your full name? If you could add @mattsches suggestion this would be great, otherwise I'll merge this as is the next days. In any case, thanks for finding and fixing this bug.