Stdlib: date_add()/date_sub()/date_modify()/date_diff() — procedural DateTime mutation (ext/date/php_date.c parity)

[PurHur]

Category

stdlib

Problem

Zend exposes procedural helpers that mutate or compare DateTime objects in place:

• date_add(DateTime $object, DateInterval $interval): DateTime
• date_sub(DateTime $object, DateInterval $interval): DateTime
• date_modify(DateTime $object, string $modifier): DateTime
• date_diff(DateTime $baseObject, DateTime $targetObject, bool $absolute = false): DateInterval

This compiler has VM DateTime OOP (#3072) but none of the procedural mutators are registered — function_exists('date_add') is false. Frameworks and legacy code call these instead of $dt->add() / $dt->modify() (which also require #3162 DateInterval).

php-src reference

• php/php-src ext/date/php_date.c — PHP_FUNCTION(date_add), date_sub, date_modify, date_diff
• php/php-src ext/date/php_date.stub.php — signatures and return types
• Shared logic: php_date_add(), php_date_sub(), php_date_modify(), php_date_diff() in php_datetime.c

Repro (failure today)

<?php
declare(strict_types=1);

$dt = new DateTime('2026-06-01 12:00:00', new DateTimeZone('UTC'));
// Requires DateInterval from #3162; use host DateInterval on Zend compare only:
$interval = new DateInterval('P1D');

date_add($dt, $interval);
echo $dt->format('Y-m-d'), "\n";

$dt2 = new DateTime('2026-06-01', new DateTimeZone('UTC'));
date_modify($dt2, '+2 days');
echo $dt2->format('Y-m-d'), "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php -r "var_export(function_exists(\"date_add\")); echo \"\\n\";"
php repro.php
'

Runtime	Result
Zend PHP 8.3+	2026-06-02 then 2026-06-03
bin/vm.php	Call to undefined function date_add()

Scope (this repo)

Area	Path
VM builtins	ext/standard/date_add.php, date_sub.php, date_modify.php, date_diff.php (or ext/date/)
Shared helper	extend lib/VM/DateTimeSupport.php — delegate to host \DateTime methods
Registration	ext/standard/Module.php
Prerequisite	#3162 DateInterval VM class (or host-bridge stub for v1)
Tests	test/compliance/cases/stdlib/date_add.phpt, date_diff.phpt
Matrix	script/capability-matrix.php

v1: VM-only; mutate in place and return the same object reference like Zend. JIT/AOT defer to #4043 DateTime method lowering.

Done when

• Repro prints Zend-matching dates on VM (with Stdlib: DateTimeImmutable / DateInterval — ext/date OOP phase 2 (#3072 follow-up) #3162 green or documented host-bridge)
• Wrong-type args throw TypeError with Zend message prefixes (not LogicException)
• date_diff() returns a DateInterval with days/invert matching Zend for the repro pair
• ./script/ci-fast.sh --filter date_add green

Related

• Stdlib: DateTime / DateTimeImmutable OOP (ext/date parity) #3072 DateTime phase 1 · Stdlib: DateTimeImmutable / DateInterval — ext/date OOP phase 2 (#3072 follow-up) #3162 DateInterval · Stdlib: date_create() / date_create_immutable() — procedural date helpers (ext/date parity) #4124 date_create() · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 self-host

[PurHur]

claim: PHP Compiler STD Lib — starting this run

[PurHur]

Merged via #8272

PHP implementation: ext/standard/date_{add,sub,modify,diff}.php + VmDateTimeNative::applyIntervalState() / diffTimestamps() + DateTimeSupport helpers. No new C runtime.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php test/repro/maintainer_date_add.php'
# 2026-06-02 / 2026-06-03

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter date_add'
# OK (2 tests, 2 assertions)

VM-only v1 (JIT/AOT deferred to #4043). Capability matrix: date_add|date_sub|date_modify|date_diff → yes|no|no.

[PurHur]

claim: PHP Compiler STD Lib — starting this run (DateTime ctor inline call-arg wiring blocks date_add/date_diff repros)

[PurHur]

Merged via #8615.

Root cause: #8561 inline call-arg bridging mapped a hoisted new DateTimeZone producer onto ctor arg #0 when arg #0 was an embedded string literal; statement-level date_add() FuncCall temps were also collected as producers for following $dt->format('Y-m-d').

Verification

vendor/bin/phpunit --filter "date_add|datetime_construct_embedded_timezone"  → OK (4/4 VM+JIT)
php bin/vm.php test/repro/maintainer_date_add.php  → 2026-06-02 / 2026-06-03
php bin/compile.php -l test/repro/maintainer_date_add.php  → exit 0

JIT/AOT lowering for date_add() itself remains tracked separately (capabilities still VM-only for JIT on those builtins).

[PurHur]

claim: PHP Compiler STD Lib — starting this run (date_add/date_sub/date_modify/date_diff JIT/AOT lowering, #4604 phase 2)

[PurHur]

Merged via #8656.

Verification (green):

• vendor/bin/phpunit --filter "DateMutationJitCompileTest|date_add" — 3 tests OK
• php bin/compile.php -l test/fixtures/aot/compile-only/date_mutation.php — exit 0
• php bin/compile.php -l test/repro/maintainer_date_add.php — exit 0
• Capability matrix: date_add, date_sub, date_modify, date_diff → VM/JIT/AOT yes

Implementation: ext/standard/JitDateMutation.php, lib/JIT/Builtin/DateMutationRuntime.php (PHP LLVM helpers, no new C runtime).

Known follow-up: full AOT compile+run for date mutation still segfaults (compile-only -l gate used); runtime date_modify for non-literal modifiers deferred.