Preliminary attempt to upgrade to Kotlin 2.2.0

build.gradle.kts

@@ -27,7 +27,7 @@ allprojects {
     }
     tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>().configureEach {
         // outputs the compiler version to logs so we can check whether the train configuration applied
-        kotlinOptions.freeCompilerArgs += "-version"
+        compilerOptions { freeCompilerArgs.add("-version") }
     }
     tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinJvmCompile>().configureEach {
         compilerOptions { freeCompilerArgs.add("-Xjvm-default=disable") }

core/build.gradle.kts

@@ -102,12 +102,6 @@ kotlin {
                 }
             }
         }
-        compilations.all {
-            kotlinOptions {
-                sourceMap = true
-                moduleKind = "umd"
-            }
-        }
 //        compilations["main"].apply {
 //            kotlinOptions {
 //                outputFile = "kotlinx-datetime-tmp.js"
@@ -411,14 +405,6 @@ tasks.configureEach {
     }
 }
 
-// Drop this configuration when the Node.JS version in KGP will support wasm gc milestone 4
-// check it here:
-// https://github.com/JetBrains/kotlin/blob/master/libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/js/nodejs/NodeJsRootExtension.kt
-with(org.jetbrains.kotlin.gradle.targets.js.nodejs.NodeJsRootPlugin.apply(rootProject)) {
-    nodeVersion = "21.0.0-v8-canary202309167e82ab1fa2"
-    nodeDownloadBaseUrl = "https://nodejs.org/download/v8-canary"
-}
-
 apiValidation {
     @OptIn(kotlinx.validation.ExperimentalBCVApi::class)
     klib {

core/common/src/DateTimeUnit.kt

@@ -152,14 +152,7 @@ public sealed class DateTimeUnit {
      * @see DateTimeUnit.MonthBased for specifically month-based units.
      */
     @Serializable(with = DateBasedDateTimeUnitSerializer::class)
-    public sealed class DateBased : DateTimeUnit() {
-        @Suppress("TOPLEVEL_TYPEALIASES_ONLY")
-        @Deprecated("Use DateTimeUnit.DayBased", ReplaceWith("DateTimeUnit.DayBased", "kotlinx.datetime.DateTimeUnit"))
-        public typealias DayBased = DateTimeUnit.DayBased
-        @Suppress("TOPLEVEL_TYPEALIASES_ONLY")
-        @Deprecated("Use DateTimeUnit.MonthBased", ReplaceWith("DateTimeUnit.MonthBased", "kotlinx.datetime.DateTimeUnit"))
-        public typealias MonthBased = DateTimeUnit.MonthBased
-    }
+    public sealed class DateBased : DateTimeUnit()
 
     /**
      * A [datetime unit][DateTimeUnit] equal to some number of calendar days.

gradle.properties

@@ -7,7 +7,7 @@ versionSuffix=SNAPSHOT
 
 tzdbVersion=2025b
 
-defaultKotlinVersion=2.1.20
+defaultKotlinVersion=2.2.0-Beta2
 dokkaVersion=2.0.0
 serializationVersion=1.6.2
 benchmarksVersion=0.7.2

serialization/build.gradle.kts

@@ -50,12 +50,6 @@ kotlin {
     js {
         nodejs {
         }
-        compilations.all {
-            kotlinOptions {
-                sourceMap = true
-                moduleKind = "umd"
-            }
-        }
     }