Amusingly, after months of pointless bikeshedding, we managed to convince the internals team to throw an exception during the extreme case of a CSPRNG failure.

https://www.sammyk.me/security-changes-to-the-php-7-csprng-i...

You can read my arguments on the mailing list, but basically it amounted to:

    $chars = 'abcdefghijklmnopqrstuvwxyz234567';
    for ($i = 0; $i < 12; ++$i) {
        $password .= $chars[random_int(0, 31)];
    }

If random_int() returned FALSE, $password would be the string 'aaaaaaaaaaaa' (and you'd have 12 E_WARNING errors in your log).

By making it an exception, random_int() will now fail closed (kill the script by default), but the developer can still handle it gracefully.

    $chars = 'abcdefghijklmnopqrstuvwxyz234567';
    try {
        for ($i = 0; $i < 12; ++$i) {
            $password .= $chars[random_int(0, 31)];   
        }
    } catch (Throwable $e) {
        $framework->template->kill('An unrecoverable fatal error occurred.');
    }

Or something similar.

Is it a BC break? Sure. Is it worth it? Oh yeah.