Filter out negative components after normalizing. Components that are too big remain, and date matching will take care of them

Author: hristost

Sources/FoundationEssentials/Calendar/Calendar_Recurrence.swift

@@ -658,37 +658,43 @@ extension Calendar {
     /// Normalized months so that all months are positive
     func _normalizedMonths(_ months: [Calendar.RecurrenceRule.Month], for anchor: Date) -> [Calendar.RecurrenceRule.Month] {
         lazy var monthRange = self.range(of: .month, in: .year, for: anchor)
-        return months.map { month in
+        return months.compactMap { month in
             if month.index > 0 {
                 return month
-            } else {
+            } else if month.index > -monthRange!.upperBound {
                 let newIndex = monthRange!.upperBound + month.index
                 // The upper bound is the last month plus one. Subtracting 1 we get the last month
                 return Calendar.RecurrenceRule.Month(newIndex, isLeap: month.isLeap)
+            } else {
+                return nil
             }
         }
     }
 
     /// Normalized days in a month so that all days are positive
     internal func _normalizedDaysOfMonth(_ days: [Int], for anchor: Date) -> [Int] {
         lazy var dayRange = self.range(of: .day, in: .month, for: anchor)
-        return days.map { day in
+        return days.compactMap { day in
             if day > 0 {
                 day
-            } else {
+            } else if day > -dayRange!.upperBound {
                 dayRange!.upperBound + day
+            } else {
+                nil
             }
         }
     }
 
     /// Normalized days in a year so that all days are positive
     internal func _normalizedDaysOfYear(_ days: [Int], for anchor: Date) -> [Int] {
         lazy var dayRange = self.range(of: .day, in: .year, for: anchor)
-        return days.map { day in
+        return days.compactMap { day in
             if day > 0 {
                 day
-            } else {
+            } else if day > -dayRange!.upperBound {
                 dayRange!.upperBound + day
+            } else {
+                nil
             }
         }
     }
@@ -709,11 +715,13 @@ extension Calendar {
             weekRange.upperBound
         }
 
-        return weeksOfYear.map { weekIdx in
+        return weeksOfYear.compactMap { weekIdx in
            if weekIdx > 0 {
                weekIdx
-           } else {
+           } else if weekIdx > -lastWeekIdx {
                lastWeekIdx + weekIdx
+           } else {
+               nil
            }
         }
     }

Tests/FoundationEssentialsTests/GregorianCalendarRecurrenceRuleTests.swift

@@ -663,4 +663,17 @@ final class GregorianCalendarRecurrenceRuleTests: XCTestCase {
         }
         // If we get here, there isn't an infinite loop
    }
+    
+   func testOutOfRangeComponents() {
+        let start = Date(timeIntervalSince1970: 1695304800.0) // 2023-09-21T14:00:00-0000
+        let end   = Date(timeIntervalSince1970: 1729519200.0) // 2024-10-21T14:00:00-0000
+        
+        var rule = Calendar.RecurrenceRule(calendar: gregorian, frequency: .monthly)
+        rule.daysOfTheMonth = [32, -32]
+        
+        let eventStart = Date(timeIntervalSince1970: 1285077600.0) // 2010-09-21T14:00:00-0000
+        let results = Array(rule.recurrences(of: eventStart, in: start..<end))
+        
+        XCTAssertEqual(results, [])
+    }
 }