Extract current Kotlin version value into a separate class

In order to selectively ignore it during classpath normalization,
and do not recompile all the dependencies when just the version value
changes.

libraries/stdlib/src/kotlin/util/KotlinVersion.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -72,6 +72,12 @@ public class KotlinVersion(val major: Int, val minor: Int, val patch: Int) : Com
          * Returns the current version of the Kotlin standard library.
          */
         @kotlin.jvm.JvmField
-        public val CURRENT: KotlinVersion = KotlinVersion(1, 4, 255) // value is written here automatically during build
+        public val CURRENT: KotlinVersion = KotlinVersionCurrentValue.get()
     }
 }
+
+// this class is ignored during classpath normalization when considering whether to recompile dependencies in Kotlin build
+private object KotlinVersionCurrentValue {
+    @kotlin.jvm.JvmStatic
+    fun get(): KotlinVersion = KotlinVersion(1, 4, 255) // value is written here automatically during build
+}

prepare/build.version/build.gradle.kts

@@ -35,7 +35,7 @@ val writeStdlibVersion by tasks.registering {
     inputs.property("version", kotlinVersion)
     outputs.file(versionFile)
     doLast {
-        replaceVersion(versionFile, """val CURRENT: KotlinVersion = KotlinVersion\((\d+, \d+, \d+)\)""") {
+        replaceVersion(versionFile, """fun get\(\): KotlinVersion = KotlinVersion\((\d+, \d+, \d+)\)""") {
             val (major, minor, _, optPatch) = Regex("""^(\d+)\.(\d+)(\.(\d+))?""").find(kotlinVersion)?.destructured ?: error("Cannot parse current version $kotlinVersion")
             val newVersion = "$major, $minor, ${optPatch.takeIf { it.isNotEmpty() } ?: "0" }"
             logger.lifecycle("Writing new standard library version components: $newVersion")