Stdlib: DateTime::createFromTimestamp() float $timestamp — fractional seconds truncated (extends #5973, ext/date/php_date.c) #9984

Category

stdlib · php-src-strict · extends #5973

Problem

DateTime::createFromTimestamp() / DateTimeImmutable::createFromTimestamp() exist (#5973) for int timestamps, but PHP 8.4 accepts int|float and preserves subsecond precision.

VM lowers the argument via VmMath::parseIntBuiltinArg() in DateTimeCreateFromTimestamp.php, so 1700000000.5 formats as 1700000000.000000 instead of 1700000000.500000.

php-src reference

• ext/date/php_date.c — zim_DateTime_createFromTimestamp, float microsecond handling
• Zend/zend_interfaces.c — timestamp parsing

Repro

test/repro/datetime_create_from_timestamp_float.php:

<?php
date_default_timezone_set('UTC');
$dt = DateTime::createFromTimestamp(1_700_000_000.5);
echo $dt->format('U.u'), "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php test/repro/datetime_create_from_timestamp_float.php'
# VM today: 1700000000.000000
# php-src 8.4: 1700000000.500000

Implementation hints (PHP-in-PHP)

• Accept int|float in DateTimeCreateFromTimestamp / DateTimeImmutableCreateFromTimestamp
• Extend DateTimeSupport::initDateTimeFromTimestamp() to split integer seconds + fractional part into date object fields (mirror php-src timelib)
• Update compliance datetime_create_from_timestamp.phpt with float case
• JIT/AOT: same semantics when methods are lowered

Scope

• lib/VM/Builtin/DateTimeCreateFromTimestamp.php
• lib/VM/Builtin/DateTimeImmutableCreateFromTimestamp.php
• lib/VM/DateTimeSupport.php

Done when

• Float repro prints 1700000000.500000 (UTC)
• Int timestamps unchanged
• Invalid types still TypeError per php-src
• Compliance .phpt extended

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php test/repro/datetime_create_from_timestamp_float.php'
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php vendor/bin/phpunit test/compliance/cases/stdlib/datetime_create_from_timestamp.phpt'