Fix overflow when subtracting Int.MIN_VALUE

Author: dkhalanskyjb

core/commonMain/src/Instant.kt

@@ -342,8 +342,7 @@ public expect fun Instant.plus(value: Int, unit: DateTimeUnit, timeZone: TimeZon
  *
  * @throws DateTimeArithmeticException if this value or the result is too large to fit in [LocalDateTime].
  */
-public fun Instant.minus(value: Int, unit: DateTimeUnit, timeZone: TimeZone): Instant =
-    plus(-value, unit, timeZone)
+public expect fun Instant.minus(value: Int, unit: DateTimeUnit, timeZone: TimeZone): Instant
 
 /**
  * Returns an instant that is the result of adding the [value] number of the specified [unit] to this instant.
@@ -365,7 +364,7 @@ public fun Instant.plus(value: Int, unit: DateTimeUnit.TimeBased): Instant =
  * The return value is clamped to the platform-specific boundaries for [Instant] if the result exceeds them.
  */
 public fun Instant.minus(value: Int, unit: DateTimeUnit.TimeBased): Instant =
-    plus(-value.toLong(), unit)
+    minus(value.toLong(), unit)
 
 /**
  * Returns an instant that is the result of adding the [value] number of the specified [unit] to this instant

core/commonMain/src/LocalDate.kt

@@ -223,7 +223,7 @@ public expect fun LocalDate.plus(value: Int, unit: DateTimeUnit.DateBased): Loca
  *
  * @throws DateTimeArithmeticException if the result exceeds the boundaries of [LocalDate].
  */
-public fun LocalDate.minus(value: Int, unit: DateTimeUnit.DateBased): LocalDate = plus(-value, unit)
+public expect fun LocalDate.minus(value: Int, unit: DateTimeUnit.DateBased): LocalDate
 
 /**
  * Returns a [LocalDate] that is the result of adding the [value] number of the specified [unit] to this date.

core/commonTest/src/InstantTest.kt

@@ -466,6 +466,19 @@ class InstantRangeTest {
             assertArithmeticFails("$instant") { instant.plus(DateTimePeriod(seconds = Long.MAX_VALUE), UTC) }
             assertArithmeticFails("$instant") { instant.plus(DateTimePeriod(seconds = Long.MIN_VALUE), UTC) }
         }
+        // Arithmetic overflow in an Int
+        for (instant in smallInstants + listOf(maxValidInstant)) {
+            assertEquals(instant.epochSeconds + Int.MIN_VALUE,
+                instant.plus(Int.MIN_VALUE, DateTimeUnit.SECOND, UTC).epochSeconds)
+            assertEquals(instant.epochSeconds - Int.MAX_VALUE,
+                instant.minus(Int.MAX_VALUE, DateTimeUnit.SECOND, UTC).epochSeconds)
+        }
+        for (instant in smallInstants + listOf(minValidInstant)) {
+            assertEquals(instant.epochSeconds + Int.MAX_VALUE,
+                instant.plus(Int.MAX_VALUE, DateTimeUnit.SECOND, UTC).epochSeconds)
+            assertEquals(instant.epochSeconds - Int.MIN_VALUE,
+                instant.minus(Int.MIN_VALUE, DateTimeUnit.SECOND, UTC).epochSeconds)
+        }
         // Overflowing a LocalDateTime in input
         maxValidInstant.plus(DateTimePeriod(nanoseconds = -1), UTC)
         minValidInstant.plus(DateTimePeriod(nanoseconds = 1), UTC)

core/jsMain/src/Instant.kt

@@ -178,6 +178,12 @@ public actual fun Instant.plus(value: Int, unit: DateTimeUnit, timeZone: TimeZon
             throw e
         }
 
+public actual fun Instant.minus(value: Int, unit: DateTimeUnit, timeZone: TimeZone): Instant =
+    if (value == Int.MIN_VALUE)
+        plus(-value.toLong(), unit, timeZone)
+    else
+        plus(-value, unit, timeZone)
+
 actual fun Instant.plus(value: Long, unit: DateTimeUnit.TimeBased): Instant =
     try {
         multiplyAndDivide(value, unit.nanoseconds, NANOS_PER_ONE.toLong()).let { (d, r) ->

core/jsMain/src/LocalDate.kt

@@ -50,6 +50,7 @@ public actual class LocalDate internal constructor(internal val value: jtLocalDa
 
 public actual fun LocalDate.plus(unit: DateTimeUnit.DateBased): LocalDate = plusNumber(1, unit)
 public actual fun LocalDate.plus(value: Int, unit: DateTimeUnit.DateBased): LocalDate = plusNumber(value, unit)
+public actual fun LocalDate.minus(value: Int, unit: DateTimeUnit.DateBased): LocalDate = plusNumber(-value, unit)
 public actual fun LocalDate.plus(value: Long, unit: DateTimeUnit.DateBased): LocalDate = plusNumber(value, unit)
 
 private fun LocalDate.plusNumber(value: Number, unit: DateTimeUnit.DateBased): LocalDate =

core/jvmMain/src/Instant.kt

@@ -110,6 +110,9 @@ public actual fun Instant.plus(unit: DateTimeUnit, timeZone: TimeZone): Instant
 public actual fun Instant.plus(value: Int, unit: DateTimeUnit, timeZone: TimeZone): Instant =
         plus(value.toLong(), unit, timeZone)
 
+public actual fun Instant.minus(value: Int, unit: DateTimeUnit, timeZone: TimeZone): Instant =
+        plus(-value.toLong(), unit, timeZone)
+
 public actual fun Instant.plus(value: Long, unit: DateTimeUnit, timeZone: TimeZone): Instant =
         try {
             val thisZdt = atZone(timeZone)

core/jvmMain/src/LocalDate.kt

@@ -55,6 +55,9 @@ public actual fun LocalDate.plus(unit: DateTimeUnit.DateBased): LocalDate =
 public actual fun LocalDate.plus(value: Int, unit: DateTimeUnit.DateBased): LocalDate =
         plus(value.toLong(), unit)
 
+public actual fun LocalDate.minus(value: Int, unit: DateTimeUnit.DateBased): LocalDate =
+        plus(-value.toLong(), unit)
+
 public actual fun LocalDate.plus(value: Long, unit: DateTimeUnit.DateBased): LocalDate =
         try {
             when (unit) {

core/nativeMain/src/Instant.kt

@@ -297,6 +297,8 @@ public actual fun Instant.plus(unit: DateTimeUnit, timeZone: TimeZone): Instant
     plus(1L, unit, timeZone)
 public actual fun Instant.plus(value: Int, unit: DateTimeUnit, timeZone: TimeZone): Instant =
     plus(value.toLong(), unit, timeZone)
+public actual fun Instant.minus(value: Int, unit: DateTimeUnit, timeZone: TimeZone): Instant =
+    plus(-value.toLong(), unit, timeZone)
 public actual fun Instant.plus(value: Long, unit: DateTimeUnit, timeZone: TimeZone): Instant = try {
     when (unit) {
         is DateTimeUnit.DateBased -> {

core/nativeMain/src/LocalDate.kt

@@ -259,6 +259,8 @@ public actual fun LocalDate.plus(value: Int, unit: DateTimeUnit.DateBased): Loca
         throw DateTimeArithmeticException("Boundaries of LocalDate exceeded when adding a value", e)
     }
 
+public actual fun LocalDate.minus(value: Int, unit: DateTimeUnit.DateBased): LocalDate = plus(-value, unit)
+
 public actual fun LocalDate.plus(value: Long, unit: DateTimeUnit.DateBased): LocalDate =
         if (value > Int.MAX_VALUE || value < Int.MIN_VALUE)
             throw DateTimeArithmeticException("Can't add a Long to a LocalDate") // TODO: less specific message