From 197c7c9e2507f3a68a047afc673fdb4f8bd81f89 Mon Sep 17 00:00:00 2001
From: fabon <syobon.hinata.public@gmail.com>
Date: Thu, 10 Oct 2024 13:55:44 +0900
Subject: [PATCH] Reject PlainYearMonth with different calendar in comparison

---
 src/datetime/_compare.ts | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/datetime/_compare.ts b/src/datetime/_compare.ts
index d39c143..0aa0023 100644
--- a/src/datetime/_compare.ts
+++ b/src/datetime/_compare.ts
@@ -56,6 +56,9 @@ export function compare(a: ComparableDateTimeType, b: ComparableDateTimeType) {
 		return getConstructor(a).compare(a, b);
 	}
 	if (isPlainYearMonth(a) && isPlainYearMonth(b)) {
+		if (a.calendarId !== b.calendarId) {
+			throw new Error("Can't compare PlainYearMonth with different calendar");
+		}
 		return getConstructor(a).compare(a, b);
 	}
 	if (isPlainMonthDay(a) || isPlainMonthDay(b)) {