Preserve some source-level compatibility

Author: dkhalanskyjb

core/jvm/src/LocalDate.kt

@@ -78,6 +78,13 @@ public actual class LocalDate internal constructor(internal val value: jtLocalDa
     public actual fun toEpochDays(): Int = value.toEpochDay().clampToInt()
 }
 
+@Deprecated(
+    "Use kotlinx.datetime.Month",
+    ReplaceWith("LocalDate(year, month.toKotlinMonth(), dayOfMonth)")
+)
+public fun LocalDate(year: Int, month: java.time.Month, dayOfMonth: Int): LocalDate =
+    LocalDate(year, month.toKotlinMonth(), dayOfMonth)
+
 @Deprecated("Use the plus overload with an explicit number of units", ReplaceWith("this.plus(1, unit)"))
 public actual fun LocalDate.plus(unit: DateTimeUnit.DateBased): LocalDate =
         plus(1L, unit)
@@ -149,3 +156,6 @@ public actual fun LocalDate.monthsUntil(other: LocalDate): Int =
 
 public actual fun LocalDate.yearsUntil(other: LocalDate): Int =
         this.value.until(other.value, ChronoUnit.YEARS).clampToInt()
+
+@Deprecated("Use kotlinx.datetime.Month", ReplaceWith("toKotlinMonth().number"))
+public val java.time.Month.number: Int get() = toKotlinMonth().number

core/jvm/src/LocalDateTime.kt

@@ -82,3 +82,24 @@ public actual class LocalDateTime internal constructor(internal val value: jtLoc
 
 }
 
+@Deprecated(
+    "Use kotlinx.datetime.Month",
+    ReplaceWith("LocalDateTime(year, month.toKotlinMonth(), dayOfMonth, hour, minute, second, nanosecond)")
+)
+public fun LocalDateTime(
+    year: Int,
+    month: java.time.Month,
+    dayOfMonth: Int,
+    hour: Int,
+    minute: Int,
+    second: Int = 0,
+    nanosecond: Int = 0
+): LocalDateTime = LocalDateTime(
+    year,
+    month.toKotlinMonth(),
+    dayOfMonth,
+    hour,
+    minute,
+    second,
+    nanosecond
+)

core/jvm/src/LocalTime.kt

@@ -90,3 +90,10 @@ public actual class LocalTime internal constructor(internal val value: jtLocalTi
 
     }
 }
+
+@Deprecated(
+    "Use kotlinx.datetime.Month",
+    ReplaceWith("atDate(year, month.toKotlinMonth(), dayOfMonth)")
+)
+public fun LocalTime.atDate(year: Int, month: java.time.Month, dayOfMonth: Int = 0): LocalDateTime =
+    atDate(year, month.toKotlinMonth(), dayOfMonth)

core/jvm/test/DeprecationReplacements.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2019-2024 JetBrains s.r.o. and contributors.
+ * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
+ */
+package kotlinx.datetime.test
+
+import kotlinx.datetime.*
+
+/**
+ * To test the deprecation replacements, remove the `Suppress` annotation and try automatically replacing the deprecated
+ * API usages with the new ones.
+ */
+@Suppress("DEPRECATION")
+class DeprecationReplacements {
+    fun localTimeAtDate() {
+        LocalTime(18, 43, 15, 100500000)
+            .atDate(2023, java.time.Month.JANUARY, 20)
+    }
+
+    fun monthNumber() {
+        java.time.Month.JANUARY.number
+    }
+
+    fun localDateConstruction() {
+        LocalDate(2023, java.time.Month.JANUARY, 20)
+    }
+
+    fun localDateTimeConstruction() {
+        LocalDateTime(2023, java.time.Month.JANUARY, 20, 18, 43, 15, 100500000)
+        LocalDateTime(2023, java.time.Month.JANUARY, 20, 18, 43, 15)
+        LocalDateTime(2023, java.time.Month.JANUARY, 20, 18, 43)
+    }
+}