Fix ambiguous time at the end of DST period on Windows

MaximLipnin · scott-ferguson-unity · commit 9d66cfbc0ebd · 2020-12-15T09:10:58.000-05:00
diff --git a/mcs/class/corlib/System/TimeZoneInfo.cs b/mcs/class/corlib/System/TimeZoneInfo.cs
@@ -955,8 +955,9 @@ bool IsInDSTForYear (AdjustmentRule rule, DateTime dateTime, int year)
 			DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));
 			if (dateTime.Kind == DateTimeKind.Utc) {
 				DST_start -= BaseUtcOffset;
-				DST_end -= (BaseUtcOffset + rule.DaylightDelta);
+				DST_end -= BaseUtcOffset;
 			}
+			DST_end -= rule.DaylightDelta;
 			return (dateTime >= DST_start && dateTime < DST_end);
 		}
 		

Original file line number	Diff line number	Diff line change
`@@ -955,8 +955,9 @@ bool IsInDSTForYear (AdjustmentRule rule, DateTime dateTime, int year)`
`955`	`955`	`DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));`
`956`	`956`	`if (dateTime.Kind == DateTimeKind.Utc) {`
`957`	`957`	`DST_start -= BaseUtcOffset;`
`958`		`- DST_end -= (BaseUtcOffset + rule.DaylightDelta);`
	`958`	`+ DST_end -= BaseUtcOffset;`
`959`	`959`	`}`
	`960`	`+ DST_end -= rule.DaylightDelta;`
`960`	`961`	`return (dateTime >= DST_start && dateTime < DST_end);`
`961`	`962`	`}`
`962`	`963`