Regression: IntlDateFormatter locale @calendar=hebrew/islamic/japanese/buddhist — formats Gregorian (ext/intl/dateformat)

[PurHur]

Category

bug · php-src-strict · IntlDateFormatter calendar locale keyword

Problem

Constructing IntlDateFormatter with locale en_US@calendar=<non-gregorian> and IntlDateFormatter::TRADITIONAL must format using that calendar. VM ignores the @calendar keyword and emits Gregorian (or time-only) output.

Repro (format(0), FULL date, NONE time, UTC, TRADITIONAL)	Zend 8.2+	VM (2026-07-24)
en_US@calendar=hebrew	Thursday, 23 Tevet 5730	Gregorian / time-only (not Hebrew)
en_US@calendar=islamic	Thursday, Shawwal 23, 1389 AH	not Islamic
en_US@calendar=japanese	Thursday, January 1, 45 Shōwa	not Japanese era
en_US@calendar=buddhist	Thursday, January 1, 2513 BE	not Buddhist era

php-src reference

• php/php-src ext/intl/dateformat/dateformat_create.cpp — locale calendar keyword + UDAT_TRADITIONAL
• ICU uloc_setKeywordValue("calendar", …) / udat_open calendar

PHP implementation target

• ext/intl/VmIntlDateFormatter.php — honor @calendar= in locale when calendar arg is TRADITIONAL (and when unset defaults follow locale); wire through format path
• Prefer PHP-in-PHP ICU bindings already used elsewhere; no new runtime/*.c logic

Repro

cat > /tmp/idf_cal.php <<'PHP'
<?php
foreach (['hebrew','islamic','japanese','buddhist'] as $cal) {
  $df = new IntlDateFormatter(
    \"en_US@calendar=$cal\",
    IntlDateFormatter::FULL,
    IntlDateFormatter::NONE,
    'UTC',
    IntlDateFormatter::TRADITIONAL
  );
  echo \"$cal: \" . $df->format(0) . \"\n\";
}
PHP
./script/docker-exec.sh -- bash -lc 'php /tmp/idf_cal.php; php bin/vm.php /tmp/idf_cal.php'

Host-confirmed (2026-07-24, master b076674e2).

Done when

• Each @calendar= locale above matches Zend date string family (era/month names)
• Compliance .phpt under test/compliance/cases/intl/
• php-src-strict; no php-compiler-strict shortcut

[PurHur]

claim: PHP Compiler STD Lib Advanced — batch (issues #22870, #22877, #22855, #22699) — queued after #22870