From 53b33c03679f425e4e8504444d0f18f2d79aad5e Mon Sep 17 00:00:00 2001
From: Philip Chimento <pchimento@igalia.com>
Date: Fri, 14 Feb 2025 16:19:50 -0800
Subject: [PATCH] Polyfill: Fix parsing of calendar identifier from time-only
 string

https://tc39.es/proposal-temporal/#sec-temporal-parsetemporalcalendarstring
ParseTemporalCalendarString specifies to try to parse the string as
TemporalDateTimeString[+Zoned], TemporalDateTimeString[~Zoned],
TemporalInstantString, TemporalTimeString, TemporalMonthDayString, and
TemporalYearMonthString consecutively until one succeeds. I always thought
TemporalTimeString would be handled by ParseISODateTime in the polyfill,
but it seems I was wrong about that.

See: #3090
---
 polyfill/lib/ecmascript.mjs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/polyfill/lib/ecmascript.mjs b/polyfill/lib/ecmascript.mjs
index 3ac0ac8f6..3d7840cb7 100644
--- a/polyfill/lib/ecmascript.mjs
+++ b/polyfill/lib/ecmascript.mjs
@@ -1741,9 +1741,13 @@ export function ToTemporalCalendarIdentifier(calendarLike) {
     ({ calendar } = ParseISODateTime(identifier));
   } catch {
     try {
-      ({ calendar } = ParseTemporalYearMonthString(identifier));
+      ({ calendar } = ParseTemporalTimeString(identifier));
     } catch {
-      ({ calendar } = ParseTemporalMonthDayString(identifier));
+      try {
+        ({ calendar } = ParseTemporalYearMonthString(identifier));
+      } catch {
+        ({ calendar } = ParseTemporalMonthDayString(identifier));
+      }
     }
   }
   if (!calendar) calendar = 'iso8601';