Add ZPP checks to count()

[Girgias]

A new take on #4572 as it was declined due to the prevalence of using count on NULL.
This allows to use NULL with count but deprecates its usage (which I consider valid as it was a warning in PHP 7.2+).

It also adds some checks on the $mode argument.

However I needed to change the test runner again because apparently there is a weird edge case which I cannot reproduce in a test file.

[kocsismate]

I am not sure if it is really an argument or a counter-argument, but I'd like to share this with you. So the other day I found a piece of code in our codebase which says:
if (count($userIds > 0)) {

I am sure that there are tons of such code in the wild... So on one hand, all these code would result in an exception all of the sudden by this PR, but on the other hand, such issues would be almost impossible to commit in the first place.

[Girgias]

I am not sure if it is really an argument or a counter-argument, but I'd to share this with you. So the other day I found a piece of code in our codebase which says:
if (count($userIds > 0)) {

I am sure that there are tons of such code in the wild... So on one hand, all these code would result in an exception all of the sudden by this PR, but on the other hand, such issues would be almost impossible to commit in the first place.

Isn't this already producing a "type error" warning (as of 7.2)? The rationale for this PR (and the previous one) is to align its behaviour as per the Consistent Type Error RFC. [1]

However it is always good to know that there is surprising code in the wild, because I have no clue what are the expected result of count() on a boolean.

The previous on was closed as using count() like empty() to check for null seems to be pretty prevalent. However the boolean one is new to me :D

[1] https://wiki.php.net/rfc/consistent_type_errors

[kocsismate]

Isn't this already producing a "type error" warning (as of 7.2)?

I haven't seen any warning (but we are not yet on PHP 7.2).

The previous on was closed as using count() like empty() to check for null seems to be pretty prevalent.

Having forgotten about your PR, I also tried to promote this warning to an exception in October. ^^

All in all, I am also in favour of promoting this warning, I just wanted to highlight this aspect of the change.

[Girgias]

Isn't this already producing a "type error" warning (as of 7.2)?

I haven't seen any warning (but we are not yet on PHP 7.2).

For reference: https://www.php.net/manual/en/migration72.incompatible.php#migration72.incompatible.warn-on-non-countable-types

The previous on was closed as using count() like empty() to check for null seems to be pretty prevalent.

Having forgotten about your PR, I also tried to promote this warning to an exception in October. ^^

All in all, I am also in favour of promoting this warning, I just wanted to highlight this aspect of the change.

Makes sense :)

[kocsismate]

For reference:

What I really wanted to say is that I hadn't seen any warnings in our logs 😅 But the reason is obvious then ^^

[Girgias]

For reference:

What I really wanted to say is that I hadn't seen any warnings in our logs 😅 But the reason is obvious then ^^

I know just pointing out the relevant section of the upgrading document (because I wasn't sure myself if it was 7.2) :)