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

[DanielEScherzer]

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 b675db4

I did not test against all extensions, `php -m` output provided

[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() );

List of the 17 classes

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.

List of those classes

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

[nielsdos]

FWIW even when this is fixed, the DOM classes will keep throwing an exception in your test because you're using them in an incorrect way. You should be constructing them via the document and register a custom class via registerNodeClass

[DanielEScherzer]

FWIW even when this is fixed, the DOM classes will keep throwing an exception in your test because you're using them in an incorrect way. You should be constructing them via the document and register a custom class via registerNodeClass

I realize that I'm not using them the way that the DOM extension expects, but since we aren't actually using them for any DOM-related things, why would these keep throwing exceptions? I would expect that __debugInfo() when called on a class that defines its own such method would trigger that method, and, if it doesn't include parent::__debugInfo(), never trigger the base class's handling that would throw exceptions.

[nielsdos]

Right, brainfart, indeed that would work.

[DanielEScherzer]

Since I don't have the permission to edit labels, this should probably be tagged with the various extensions - I see

6 extensions

Original list had 25 and was wrong

• date
• DOM
• intl
• mysqli
• spl
• xmlreader

Plus:
Zend - built in functions (stdClass), exceptions, generators

Though for a few of these, fixing the handling in the base Exception and Error classes might solve all of the extension's classes

[nielsdos]

Since this applies to multiple extensions, maybe a general solution should be made.

[DanielEScherzer]

Maybe something in the handling of class registration that does not copy the parent get_debug_info, or rather does not call that for non-internal classes that define the method themselves? I can try and take a look

If we are going with a general solution, we may not want to go with #12534 though

[DanielEScherzer]

Update: thats what I get for coding late at night - the actual list is only 20 classes, from date, dom, intl, spl, mysqli, and XMLReader. I've updated the list in the task description - its probably a good thing we didn't tag this issue with all of the extensions