Object dumping improvements

[Girgias]

Core: convert bail-out for incorrect __debugInfo return type to TypeError

This commit, with the follow-up to fix the semantics of the object handler; should fix issue #7922.

This commit also changes the API get_debug_info and the get_properties_for (with the ZEND_PROP_PURPOSE_DEBUG purpose) objects handlers to only be allowed to return a NULL pointer when an exception has been thrown, otherwise an empty HashTable must be returned, this can be done by returning (HashTable*)&zend_empty_array; (and set *is_temp = false for the get_debug_info handler).

It is possible for extensions to have cross-version compatible code by returning an empty array instead of NULL already.

This also "fixes" the issue of dumping an object when the handler throws an exception, as can be seen by change in the expectation of the ext/ffi/tests/035.phpt test.

Zend: convert debug handler to take a bool pointer

This commit is "just" to use more appropriate types and can be dropped or pushed to a later release.

Part of the motivation to include this with the above change is to make extension developers aware of the API change, as most compilers will warn/error about incompatible function signatures.

ext/standard/var.c: show unset properties

This commit fixes some of the inconsistencies with the number of properties indicated in var_dump() and how many are actually displayed. This is because currently uninitialized typed properties are not taken into account via the call to zend_array_count() and thus do not "count" but are displayed anyway.
See the change in Zend/tests/ctor_promotion_untyped_default.phpt for an explanation of what I mean.

However, for it to be perfectly consistent we need to show properties that have been unset(), and this what I've done.

This last commit, will likely require discussions on the Internals mailing list, but I would like to get preliminary opinions about the idea itself.

[iluuu1994]

Isn't the problem here that this can result in partial output? E.g:

class C {
    public function __debugInfo(): array {
        return 'nope';
    }
}

$c = new C();

try {
    var_dump([1, 2, $c, 4]);
} catch (Error $e) {
    echo $e->getMessage(), "\n";
}

array(4) {
[0]=>
int(1)
[1]=>
int(2)
[2]=>
[3]=>
int(4)
}
__debuginfo() must return an array

I'm not sure this is desirable.

Changing the output of var_dump for unset properties also sounds like RFC territory.

[devnexen]

Zend: convert debug handler to take a bool pointer

This commit is "just" to use more appropriate types and can be dropped or pushed to a later release.

Part of the motivation to include this with the above change is to make extension developers aware of the API change, as most compilers will warn/error about incompatible function signatures.

In favor, but would prefer for 9.0 perhaps.

[derickr]

OK from me for the changes to ext/date (just moving int to bool).