Switch -jvm-target default to null

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/DefaultValues.kt

@@ -36,7 +36,7 @@ open class DefaultValues(val defaultValue: String, val possibleValues: List<Stri
     )
 
     object JvmTargetVersions : DefaultValues(
-        "\"" + JvmTarget.DEFAULT.description + "\"",
+        "null",
         JvmTarget.values().map { "\"${it.description}\"" }
     )
 

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt

@@ -89,7 +89,7 @@ class K2JVMCompilerArguments : CommonCompilerArguments() {
         valueDescription = "<version>",
         description = "Target version of the generated JVM bytecode (1.6 (DEPRECATED), 1.8, 9, 10, 11, 12, 13, 14, 15, 16 or 17), default is 1.8"
     )
-    var jvmTarget: String? by NullableStringFreezableVar(JvmTarget.DEFAULT.description)
+    var jvmTarget: String? by NullableStringFreezableVar(null)
 
     @GradleOption(DefaultValues.BooleanFalseDefault::class)
     @Argument(value = "-java-parameters", description = "Generate metadata for Java 1.8 reflection on method parameters")

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/jvmArguments.kt

@@ -76,6 +76,11 @@ fun CompilerConfiguration.setupJvmSpecificArguments(arguments: K2JVMCompilerArgu
         }
     }
 
+    if (get(JVMConfigurationKeys.JVM_TARGET) == null) {
+        put(JVMConfigurationKeys.JVM_TARGET, JvmTarget.JVM_1_8)
+    }
+
+
     val jvmTarget = get(JVMConfigurationKeys.JVM_TARGET) ?: JvmTarget.DEFAULT
     if (jvmTarget.majorVersion < JvmTarget.JVM_1_8.majorVersion) {
         val jvmDefaultMode = languageVersionSettings.getFlag(JvmAnalysisFlags.jvmDefaultMode)

compiler/tests/org/jetbrains/kotlin/jvm/compiler/Java11ModulesIntegrationTest.kt

@@ -33,7 +33,6 @@ class Java11ModulesIntegrationTest : AbstractKotlinCompilerIntegrationTest() {
 
         val kotlinOptions = mutableListOf(
             "-jdk-home", KtTestUtil.getJdk11Home().path,
-            "-jvm-target", "1.8",
             "-Xmodule-path=$paths"
         )
         if (addModules.isNotEmpty()) {

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/KotlinJavaToolchainTest.kt

@@ -573,9 +573,9 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
                 tasks.named("compileKotlin") {
                     doLast {
                         def actualJvmTarget = filteredArgumentsMap['jvmTarget']
-                        if (actualJvmTarget != "1.8") {
+                        if (actualJvmTarget != "null") {
                             //noinspection GroovyAssignabilityCheck
-                            throw new GradleException("Expected `jvmTarget` value is '1.8' but the actual value was ${'$'}actualJvmTarget")
+                            throw new GradleException("Expected `jvmTarget` value is 'null' but the actual value was ${'$'}actualJvmTarget")
                         }
                     }
                 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/dsl/KotlinJvmOptions.kt

@@ -21,9 +21,9 @@ interface KotlinJvmOptions  : org.jetbrains.kotlin.gradle.dsl.KotlinCommonOption
     /**
      * Target version of the generated JVM bytecode (1.6 (DEPRECATED), 1.8, 9, 10, 11, 12, 13, 14, 15, 16 or 17), default is 1.8
      * Possible values: "1.6", "1.8", "9", "10", "11", "12", "13", "14", "15", "16", "17"
-     * Default value: "1.8"
+     * Default value: null
      */
-     var jvmTarget: kotlin.String
+     var jvmTarget: kotlin.String?
 
     /**
      * Name of the generated .kotlin_module file

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/dsl/KotlinJvmOptionsBase.kt

@@ -47,12 +47,7 @@ internal abstract class KotlinJvmOptionsBase : org.jetbrains.kotlin.gradle.dsl.K
     @Deprecated(message = "This option is not working well with Gradle caching and will be removed in the future.", level = DeprecationLevel.WARNING)
     override var jdkHome: kotlin.String? = null
 
-    internal var jvmTargetField: kotlin.String? = null
+    override var jvmTarget: kotlin.String? = null
-    override var jvmTarget: kotlin.String
-        get() = jvmTargetField ?: "1.8"
-        set(value) {
-            jvmTargetField = value
-        }
 
     override var moduleName: kotlin.String? = null
 
@@ -95,7 +90,7 @@ internal abstract class KotlinJvmOptionsBase : org.jetbrains.kotlin.gradle.dsl.K
         useFirField?.let { args.useFir = it }
         javaParametersField?.let { args.javaParameters = it }
         jdkHome?.let { args.jdkHome = it }
-        jvmTargetField?.let { args.jvmTarget = it }
+        jvmTarget?.let { args.jvmTarget = it }
         moduleName?.let { args.moduleName = it }
         noJdkField?.let { args.noJdk = it }
         noStdlibField?.let { args.noStdlib = it }
@@ -113,7 +108,7 @@ internal fun org.jetbrains.kotlin.cli.common.arguments.K2JVMCompilerArguments.fi
     useFir = false
     javaParameters = false
     jdkHome = null
-    jvmTarget = "1.8"
+    jvmTarget = null
     moduleName = null
     noJdk = false
     noStdlib = true

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/DefaultKotlinJavaToolchain.kt

@@ -155,7 +155,7 @@ internal abstract class DefaultKotlinJavaToolchain @Inject constructor(
 
             // parentKotlinOptionsImpl is set from 'kotlin-android' plugin
             val appliedJvmTargets = listOfNotNull(task.kotlinOptions, task.parentKotlinOptionsImpl.orNull)
-                .mapNotNull { (it as KotlinJvmOptionsImpl).jvmTargetField }
+                .mapNotNull { (it as KotlinJvmOptionsImpl).jvmTarget }
 
             if (appliedJvmTargets.isEmpty()) {
                 // For Java 9 and Java 10 JavaVersion returns "1.9" or "1.10" accordingly
@@ -180,7 +180,7 @@ internal abstract class DefaultKotlinJavaToolchain @Inject constructor(
             kotlinCompileTaskProvider()?.let { task ->
                 // parentKotlinOptionsImpl is set from 'kotlin-android' plugin
                 val appliedJvmTargets = listOfNotNull(task.kotlinOptions, task.parentKotlinOptionsImpl.orNull)
-                    .mapNotNull { (it as KotlinJvmOptionsImpl).jvmTargetField }
+                    .mapNotNull { (it as KotlinJvmOptionsImpl).jvmTarget }
 
                 if (appliedJvmTargets.isEmpty()) {
                     // For Java 9 and Java 10 JavaVersion returns "1.9" or "1.10" accordingly

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt

@@ -35,6 +35,7 @@ import org.jetbrains.kotlin.cli.common.arguments.K2JSCompilerArguments
 import org.jetbrains.kotlin.cli.common.arguments.K2JVMCompilerArguments
 import org.jetbrains.kotlin.compilerRunner.*
 import org.jetbrains.kotlin.compilerRunner.GradleCompilerRunner.Companion.normalizeForFlagFile
+import org.jetbrains.kotlin.config.JvmTarget
 import org.jetbrains.kotlin.daemon.common.MultiModuleICSettings
 import org.jetbrains.kotlin.gradle.dsl.*
 import org.jetbrains.kotlin.gradle.incremental.*
@@ -797,10 +798,11 @@ abstract class KotlinCompile @Inject constructor(
                     else -> targetCompatibility
                 }
 
-                if (normalizedJavaTarget != args.jvmTarget) {
+                val jvmTarget = args.jvmTarget ?: JvmTarget.DEFAULT.toString()
+                if (normalizedJavaTarget != jvmTarget) {
                     val javaTaskName = associatedJavaCompileTaskName.get()
                     val errorMessage = "'$javaTaskName' task (current target is $targetCompatibility) and " +
-                            "'$name' task (current target is ${args.jvmTarget}) " +
+                            "'$name' task (current target is $jvmTarget) " +
                             "jvm target compatibility should be set to the same Java version."
                     when (jvmTargetValidationMode.get()) {
                         PropertiesProvider.JvmTargetValidationMode.ERROR -> throw GradleException(errorMessage)