Lots of classes do not allow `__debugInfo()` overrides to work

Description

Inspired by #11310, I wrote a quick test script to check if there were other classes where creating a subclass with a __debugInfo() method did not work. I found a number of such classes (the one seg fault I filed separately at #16316 since that is a bigger issue than the override just not working).

I tested against b675db4c56dd0de4ea1f5195d587ed90f0096ed8

[PHP Modules]
bcmath
calendar
Core
ctype
curl
date
dba
dom
enchant
exif
FFI
fileinfo
filter
ftp
gd
gettext
gmp
hash
iconv
intl
json
ldap
libxml
mbstring
mysqli
mysqlnd
odbc
openssl
pcntl
pcre
PDO
pdo_dblib
PDO_Firebird
pdo_mysql
PDO_ODBC
pdo_pgsql
pdo_sqlite
pgsql
Phar
posix
random
readline
Reflection
session
shmop
SimpleXML
snmp
soap
sockets
sodium
SPL
sqlite3
standard
sysvmsg
sysvsem
sysvshm
tidy
tokenizer
xml
xmlreader
xmlwriter
xsl
zend_test
zip
zlib

Approach: create a custom subclass with an empty constructor, and a __debugInfo() method returning ['x' => 'y']. The var_dump() a new instance of that subclass and check the output.

I found 17 classes across the DOM and SimpleXML extension where doing this caused an exception to be thrown relating to invalid state, e.g.

<?php

class Demo extends DOMNode {
    public function __construct() {}
    public function __debugInfo(): array {
        return ['x' => 'y'];
    }
}

var_dump( new Demo() );

DOMNode::class,
DOMNameSpaceNode::class,
DOMDocumentFragment::class,
DOMDocument::class,
DOMCharacterData::class,
DOMAttr::class,
DOMElement::class,
DOMText::class,
DOMComment::class,
DOMCdataSection::class,
DOMDocumentType::class,
DOMNotation::class,
DOMEntity::class,
DOMEntityReference::class,
DOMProcessingInstruction::class,

SimpleXMLElement::class,
SimpleXMLIterator::class,

I also found a further 20 classes where the override does not seem to work, across multiple extensions.

array (
  0 => 'DatePeriod',
  1 => 'DOMImplementation',
  2 => 'Dom\\Implementation',
  3 => 'DOMNodeList',
  4 => 'Dom\\NodeList',
  5 => 'DOMNamedNodeMap',
  6 => 'Dom\\NamedNodeMap',
  7 => 'Dom\\DtdNamedNodeMap',
  8 => 'Dom\\HTMLCollection',
  9 => 'IntlTimeZone',
  10 => 'IntlCalendar',
  11 => 'IntlGregorianCalendar',
  12 => 'IntlBreakIterator',
  13 => 'IntlRuleBasedBreakIterator',
  14 => 'IntlCodePointBreakIterator',
  15 => 'SplFixedArray',
  16 => 'mysqli',
  17 => 'mysqli_result',
  18 => 'mysqli_stmt',
  19 => 'XMLReader',
)

You can see the script I used at https://gist.github.com/DanielEScherzer/c979c15b47bc603758c4c38ba25dd510

PHP Version

dev-master

Operating System

No response

Comienza con el script de reproducción enlazado y sus comprobaciones con var_dump; después, examina las clases DOM, SimpleXML y otras clases afectadas que se indican. Reproduce las excepciones de estado no válido y las sobrescrituras que no funcionan en las clases indicadas; el trabajo estará terminado cuando el comportamiento de __debugInfo() en las subclases funcione de forma coherente sin esas excepciones.