Stdlib: DateTimeInterface built-in interface missing — ATOM constant fetch + instanceof broken (ext/date/php_date.h)

[PurHur]

Category

stdlib (ext/date OOP)

Problem

Zend registers DateTimeInterface as a built-in interface implemented by DateTime and DateTimeImmutable. This compiler does not register the interface:

• interface_exists('DateTimeInterface') → false
• DateTimeInterface::ATOM → compile error: Unknown class for constant fetch
• (new DateTime()) instanceof DateTimeInterface → false
• Parameters typed DateTimeInterface reject DateTime instances (TypeError / null)

DateTime::ATOM works because the class exists; interface-level constants and polymorphic typing do not.

php-src reference

• php/php-src ext/date/php_date.h — php_date_get_interface_ce(), DateTimeInterface registration
• php/php-src ext/date/php_date.c — register_date_interface(), format constants (ATOM, RFC3339, …)
• php/php-src ext/date/php_datetime.c — DateTime / DateTimeImmutable implement interface

Repro (failure today)

<?php
var_dump(interface_exists('DateTimeInterface'));
var_dump((new DateTime()) instanceof DateTimeInterface);
echo DateTimeInterface::ATOM, "\n";

function accepts(DateTimeInterface $dt): void {}
accepts(new DateTime());

./script/docker-exec.sh -- bash -lc 'php bin/vm.php repro.php 2>&1 | head -10'
./script/docker-exec.sh -- bash -lc 'php repro.php 2>&1'

Check	Zend PHP 8.2	This compiler
interface_exists('DateTimeInterface')	true	false
(new DateTime()) instanceof DateTimeInterface	true	false
DateTimeInterface::ATOM	Y-m-d\TH:i:sP	compile error
accepts(new DateTime())	ok	TypeError

Implementation (PHP-in-PHP)

• Register DateTimeInterface in ext/date/ (or existing date module bootstrap) with format constants mirroring php-src.
• Wire DateTime / DateTimeImmutable (when present, see Stdlib: DateTimeImmutable / DateInterval — ext/date OOP phase 2 (#3072 follow-up) #3162) to implement the interface in the class registry — no new C runtime logic.
• VM type checks / instanceof / constant fetch must resolve the interface like other built-ins.

Done when

• interface_exists('DateTimeInterface') true; constants ATOM, RFC3339, W3C, etc. match php-src values.
• DateTime and DateTimeImmutable instances satisfy instanceof DateTimeInterface.
• Parameters/properties typed DateTimeInterface accept DateTime objects.
• Compliance .phpt under test/compliance/cases/stdlib/; VM green (JIT/AOT if date types are lowered there).

Related

• Stdlib: DateTimeImmutable / DateInterval — ext/date OOP phase 2 (#3072 follow-up) #3162 (DateTimeImmutable / DateInterval OOP)
• Stdlib: DateTime::createFromInterface() / DateTimeImmutable::createFromInterface() (ext/date/php_date.c) #5936 (createFromInterface() factories — depends on interface registration)
• Stdlib: Zend builtin interfaces — interface_exists()/get_declared_interfaces() must include UnitEnum, BackedEnum, ArrayAccess, Serializable (zend_interfaces.c) #6354 (other Zend built-in interfaces)

[PurHur]

claim: agent-lane-c-implementer — starting this run

[PurHur]

Merged via PR #7509.

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php vendor/bin/phpunit test/unit/DateTimeTest.php --filter testDateTimeInterfaceRegistration
php vendor/bin/phpunit test/compliance/VMTest.php --filter datetime_interface'

Both 1/1 green. Issue repro: interface_exists('DateTimeInterface') true, (new DateTime()) instanceof DateTimeInterface true, DateTimeInterface::ATOM prints Y-m-d\\TH:i:sP, typed DateTimeInterface param accepts DateTime.