Raise 'kotlin.jvm.target.validation.mode' default value to 'error'.

Now target check intentionally runs always - even when Java sources are
empty. Java part configures publication 'org.gradle.jvm.version'
attribute which affect  published artifact consumers and should be the
same as Kotlin jvmTarget value.

^KT-54993 Fixed

libraries/stdlib/jdk8/build.gradle

@@ -110,6 +110,11 @@ task testJdk6Tests(type: Test) { thisTask ->
     })
 }
 
+tasks.named("compileModuleTestJava", JavaCompile) {
+    sourceCompatibility = JavaVersion.VERSION_1_9
+    targetCompatibility = JavaVersion.VERSION_1_9
+}
+
 compileModuleTestKotlin {
     kotlinJavaToolchain.toolchain.use(JvmToolchain.getToolchainLauncherFor(project, JdkMajorVersion.JDK_9_0))
 }

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

@@ -21,9 +21,9 @@ import kotlin.io.path.writeText
 @JvmGradlePluginTests
 class JvmTargetValidationTest : KGPBaseTest() {
 
-    @DisplayName("Should produce warning if java and kotlin jvm targets are different")
+    @DisplayName("Should produce error if java and kotlin jvm targets are different")
     @GradleTest
-    internal fun shouldWarnIfJavaAndKotlinJvmTargetsAreDifferent(gradleVersion: GradleVersion) {
+    internal fun shouldFailIfJavaAndKotlinJvmTargetsAreDifferent(gradleVersion: GradleVersion) {
         project(
             projectName = "kotlinJavaProject".fullProjectName,
             gradleVersion = gradleVersion,
@@ -32,18 +32,19 @@ class JvmTargetValidationTest : KGPBaseTest() {
             setJavaCompilationCompatibility(JavaVersion.VERSION_1_8)
             useToolchainToCompile(11)
 
-            build("assemble") {
+            buildAndFail("assemble") {
                 assertOutputContains(
                     "'compileJava' task (current target is 1.8) and 'compileKotlin' task (current target is 11) jvm target compatibility " +
-                            "should be set to the same Java version."
+                            "should be set to the same Java version.\n" +
+                            "Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain"
                 )
             }
         }
     }
 
-    @DisplayName("Should fail the build if verification mode is 'error' and kotlin and java targets are different")
+    @DisplayName("Should warn in the build log if verification mode is 'warning' and kotlin and java targets are different")
     @GradleTest
-    internal fun shouldFailBuildIfJavaAndKotlinJvmTargetsAreDifferent(gradleVersion: GradleVersion) {
+    internal fun shouldWarnBuildIfJavaAndKotlinJvmTargetsAreDifferent(gradleVersion: GradleVersion) {
         project(
             projectName = "kotlinJavaProject".fullProjectName,
             gradleVersion = gradleVersion
@@ -54,14 +55,15 @@ class JvmTargetValidationTest : KGPBaseTest() {
             gradleProperties.append(
                 """
                 # suppress inspection "UnusedProperty"
-                kotlin.jvm.target.validation.mode = error
+                kotlin.jvm.target.validation.mode = warning
                 """.trimIndent()
             )
 
-            buildAndFail("assemble") {
+            build("assemble") {
                 assertOutputContains(
                     "'compileJava' task (current target is 1.8) and 'compileKotlin' task (current target is 11) jvm target compatibility " +
-                            "should be set to the same Java version."
+                            "should be set to the same Java version.\n" +
+                            "Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain"
                 )
             }
         }
@@ -124,7 +126,14 @@ class JvmTargetValidationTest : KGPBaseTest() {
         ) {
             useToolchainToCompile(11)
 
-            JavaVersion.VERSION_1_8
+            //language=properties
+            gradleProperties.append(
+                """
+                # suppress inspection "UnusedProperty"
+                kotlin.jvm.target.validation.mode = warning
+                """.trimIndent()
+            )
+
             //language=Groovy
             buildGradle.append(
                 """
@@ -173,13 +182,6 @@ class JvmTargetValidationTest : KGPBaseTest() {
                 
                 """.trimIndent()
             )
-            //language=properties
-            gradleProperties.append(
-                """
-                # suppress inspection "UnusedProperty"
-                kotlin.jvm.target.validation.mode = error
-                """.trimIndent()
-            )
 
             build("build")
         }
@@ -194,13 +196,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
         ) {
             setJavaCompilationCompatibility(JavaVersion.VERSION_1_8)
             useToolchainToCompile(11)
-            //language=properties
+
-            gradleProperties.append(
-                """
-                # suppress inspection "UnusedProperty"
-                kotlin.jvm.target.validation.mode = error
-                """.trimIndent()
-            )
             kotlinSourcesDir().toFile().deleteRecursively()
             javaSourcesDir().resolve("demo/HelloWorld.java").deleteExisting()
 
@@ -224,9 +220,9 @@ class JvmTargetValidationTest : KGPBaseTest() {
         }
     }
 
-    @DisplayName("Should skip JVM target validation if no java sources are available")
+    @DisplayName("Should still do JVM target validation if no java sources are available")
     @GradleTest
-    internal fun shouldSkipJvmTargetValidationNoJavaSources(gradleVersion: GradleVersion) {
+    internal fun shouldDoJvmTargetValidationOnNoJavaSources(gradleVersion: GradleVersion) {
         project(
             projectName = "simple".fullProjectName,
             gradleVersion = gradleVersion,
@@ -236,11 +232,17 @@ class JvmTargetValidationTest : KGPBaseTest() {
             gradleProperties.append(
                 """
                 # suppress inspection "UnusedProperty"
-                kotlin.jvm.target.validation.mode = error
+                kotlin.jvm.target.validation.mode = warning
                 """.trimIndent()
             )
 
-            build("assemble")
+            build("assemble") {
+                assertOutputContains(
+                    "'compileJava' task (current target is 11) and 'compileKotlin' task (current target is 1.8) jvm target compatibility " +
+                            "should be set to the same Java version.\n" +
+                            "Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain"
+                )
+            }
         }
     }
 
@@ -264,7 +266,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
             )
 
             build("assemble") {
-                assertOutputDoesNotContain(
+                assertOutputContains(
                     "'compileJava' task (current target is 11) and 'compileKotlin' task (current target is 1.8) jvm target compatibility should be set to the same Java version."
                 )
             }
@@ -302,14 +304,6 @@ class JvmTargetValidationTest : KGPBaseTest() {
             gradleVersion = gradleVersion,
             buildJdk = getJdk11().javaHome
         ) {
-            //language=properties
-            gradleProperties.append(
-                """
-                # suppress inspection "UnusedProperty"
-                kotlin.jvm.target.validation.mode = error
-                """.trimIndent()
-            )
-
             val toolchainJavaVersion = if (gradleVersion < GradleVersion.version("6.9")) {
                 15
             } else {

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/Kapt3IT.kt

@@ -33,6 +33,7 @@ import org.junit.jupiter.api.condition.OS
 import java.nio.file.Files
 import java.util.zip.ZipFile
 import java.util.zip.ZipOutputStream
+import kotlin.io.path.appendText
 import kotlin.io.path.deleteExisting
 import kotlin.io.path.outputStream
 import kotlin.test.assertEquals
@@ -139,6 +140,17 @@ open class Kapt3IT : Kapt3BaseIT() {
             gradleVersion,
             buildJdk = jdk.location
         ) {
+            //language=Groovy
+            buildGradle.appendText(
+                """
+                |
+                |java {
+                |    sourceCompatibility = JavaVersion.VERSION_1_8
+                |    targetCompatibility = JavaVersion.VERSION_1_8
+                |}
+                """.trimMargin()
+            )
+
             build("assemble") {
                 assertTasksExecuted(":kaptGenerateStubsKotlin", ":kaptKotlin")
                 // Check added because of https://youtrack.jetbrains.com/issue/KT-33056.
@@ -929,16 +941,11 @@ open class Kapt3IT : Kapt3BaseIT() {
     }
 
     @DisplayName("Works with JPMS on JDK 9+")
-    @JdkVersions(versions = [JavaVersion.VERSION_11])
+    @GradleTest
-    @GradleWithJdkTest
+    fun testJpmsModule(gradleVersion: GradleVersion, ) {
-    fun testJpmsModule(
-        gradleVersion: GradleVersion,
-        jdk: JdkVersions.ProvidedJdk
-    ) {
         project(
             "jpms-module".withPrefix,
             gradleVersion,
-            buildJdk = jdk.location
         ) {
             build("assemble") {
                 assertTasksExecuted(":kaptKotlin", ":kaptGenerateStubsKotlin", ":compileKotlin", ":compileJava")

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

@@ -165,7 +165,7 @@ class KaptIncrementalWithIsolatingApt : KaptIncrementalIT() {
     }
 
     @DisplayName("KT-33617: sources in compile classpath jars")
-    @JdkVersions(versions = [JavaVersion.VERSION_1_9])
+    @JdkVersions(versions = [JavaVersion.VERSION_11])
     @GradleWithJdkTest
     fun testSourcesInCompileClasspathJars(gradleVersion: GradleVersion, jdk: JdkVersions.ProvidedJdk) {
         kaptProject(gradleVersion, buildJdk = jdk.location) {

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

@@ -357,6 +357,14 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
                 JavaVersion.VERSION_11
             )
 
+            //language=properties
+            gradleProperties.append(
+                """
+                # suppress inspection "UnusedProperty"
+                kotlin.jvm.target.validation.mode = warning
+                """.trimIndent()
+            )
+
             build("build") {
                 assertOutputContains("-jvm-target 11")
                 assertOutputDoesNotContain("-jvm-target 1.8")
@@ -414,6 +422,14 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
             setJvmTarget("1.8")
             useToolchainToCompile(11)
 
+            //language=properties
+            gradleProperties.append(
+                """
+                # suppress inspection "UnusedProperty"
+                kotlin.jvm.target.validation.mode = warning
+                """.trimIndent()
+            )
+
             build("build") {
                 assertOutputContains("-jvm-target 1.8")
                 assertOutputDoesNotContain("-jvm-target 11")
@@ -553,6 +569,14 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
             gradleVersion = gradleVersion,
             buildJdk = getJdk11().javaHome
         ) {
+            //language=properties
+            gradleProperties.append(
+                """
+                # suppress inspection "UnusedProperty"
+                kotlin.jvm.target.validation.mode = warning
+                """.trimIndent()
+            )
+
             //language=Groovy
             buildGradle.append(
                 """

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

@@ -65,6 +65,14 @@ class UpToDateIT : KGPBaseTest() {
         mutations: Set<ProjectMutation>
     ) {
         project("kotlinProject", gradleVersion) {
+            //language=properties
+            gradleProperties.append(
+                """
+                # suppress inspection "UnusedProperty"
+                kotlin.jvm.target.validation.mode = warning
+                """.trimIndent()
+            )
+
             mutations.forEach { mutation ->
                 mutation.initProject(this)
                 build("classes")

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/android/Kapt3AndroidIT.kt

@@ -131,6 +131,14 @@ class Kapt3AndroidIT : Kapt3BaseIT() {
             buildOptions = defaultBuildOptions.copy(androidVersion = agpVersion),
             buildJdk = jdkVersion.location
         ) {
+            //language=properties
+            gradleProperties.append(
+                """
+                # suppress inspection "UnusedProperty"
+                kotlin.jvm.target.validation.mode = warning
+                """.trimIndent()
+            )
+
             buildGradle.appendText(
                 """
                 apply plugin: 'kotlin-kapt'

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidIncrementalMultiModule/libJvmClassesOnly/build.gradle

@@ -2,4 +2,9 @@ apply plugin: 'kotlin'
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-}
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/jvmAndJsProject/jvmLib/build.gradle

@@ -1,3 +1,8 @@
 plugins {
     id "org.jetbrains.kotlin.jvm"
 }
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/android-inter-project-ic/lib-jvm/build.gradle

@@ -2,4 +2,9 @@ apply plugin: 'kotlin'
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-}
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/jpms-module/build.gradle

@@ -23,6 +23,10 @@ dependencies {
 
 compileKotlin.kotlinOptions.allWarningsAsErrors = true
 
+kotlin {
+    jvmToolchain(11)
+}
+
 compileJava {
     doFirst {
         options.compilerArgs += [

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/simple/build.gradle

@@ -16,4 +16,4 @@ dependencies {
     testImplementation 'junit:junit:4.13.2'
 }
 
-compileKotlin.kotlinOptions.allWarningsAsErrors = true
+compileKotlin.kotlinOptions.allWarningsAsErrors = true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kaptIncrementalAggregatingProcessorProject/build.gradle

@@ -12,6 +12,11 @@ repositories {
     }
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
+
 dependencies {
     implementation "org.jetbrains.kotlin:annotation-processor-example:$kotlin_version"
     kapt "org.jetbrains.kotlin:annotation-processor-example:$kotlin_version"

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kaptIncrementalCompilationProject/build.gradle

@@ -12,6 +12,11 @@ repositories {
     }
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
+
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
     implementation "org.jetbrains.kotlin:annotation-processor-example:$kotlin_version"

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/new-mpp-android/lib/build.gradle

@@ -25,6 +25,10 @@ android {
         }
     }
 
+    compileOptions {
+        targetCompatibility = JavaVersion.VERSION_1_8
+        sourceCompatibility = JavaVersion.VERSION_1_8
+    }
 }
 
 dependencies {

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/PropertiesProvider.kt

@@ -417,7 +417,7 @@ internal class PropertiesProvider private constructor(private val project: Proje
     }
 
     val jvmTargetValidationMode: JvmTargetValidationMode
-        get() = enumProperty("kotlin.jvm.target.validation.mode", JvmTargetValidationMode.WARNING)
+        get() = enumProperty("kotlin.jvm.target.validation.mode", JvmTargetValidationMode.ERROR)
 
     val kotlinDaemonJvmArgs: String?
         get() = this.property("kotlin.daemon.jvmargs")

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

@@ -641,9 +641,6 @@ abstract class KotlinCompile @Inject constructor(
     @get:Internal
     internal abstract val associatedJavaCompileTaskTargetCompatibility: Property<String>
 
-    @get:Internal
-    internal abstract val associatedJavaCompileTaskSources: ConfigurableFileCollection
-
     @get:Internal
     internal abstract val associatedJavaCompileTaskName: Property<String>
 
@@ -733,7 +730,7 @@ abstract class KotlinCompile @Inject constructor(
         inputChanges: InputChanges,
         taskOutputsBackup: TaskOutputsBackup?
     ) {
-        validateKotlinAndJavaHasSameTargetCompatibility(args, kotlinSources)
+        validateKotlinAndJavaHasSameTargetCompatibility(args)
 
         val scriptSources = scriptSources.asFileTree.files
         val gradlePrintingMessageCollector = GradlePrintingMessageCollector(logger, args.allWarningsAsErrors,)
@@ -784,31 +781,27 @@ abstract class KotlinCompile @Inject constructor(
 
     private fun validateKotlinAndJavaHasSameTargetCompatibility(
         args: K2JVMCompilerArguments,
-        kotlinSources: Set<File>
     ) {
-        val mixedSourcesArePresent = !associatedJavaCompileTaskSources.isEmpty &&
+        associatedJavaCompileTaskTargetCompatibility.orNull?.let { targetCompatibility ->
-                kotlinSources.isNotEmpty()
+            val normalizedJavaTarget = when (targetCompatibility) {
-        if (mixedSourcesArePresent) {
+                "6" -> "1.6"
-            associatedJavaCompileTaskTargetCompatibility.orNull?.let { targetCompatibility ->
+                "7" -> "1.7"
-                val normalizedJavaTarget = when (targetCompatibility) {
+                "8" -> "1.8"
-                    "6" -> "1.6"
+                "1.9" -> "9"
-                    "7" -> "1.7"
+                else -> targetCompatibility
-                    "8" -> "1.8"
+            }
-                    "1.9" -> "9"
-                    else -> targetCompatibility
-                }
 
-                val jvmTarget = args.jvmTarget ?: JvmTarget.DEFAULT.toString()
+            val jvmTarget = args.jvmTarget ?: JvmTarget.DEFAULT.toString()
-                if (normalizedJavaTarget != jvmTarget) {
+            if (normalizedJavaTarget != jvmTarget) {
-                    val javaTaskName = associatedJavaCompileTaskName.get()
+                val javaTaskName = associatedJavaCompileTaskName.get()
-                    val errorMessage = "'$javaTaskName' task (current target is $targetCompatibility) and " +
+                val errorMessage = "'$javaTaskName' task (current target is $targetCompatibility) and " +
-                            "'$name' task (current target is $jvmTarget) " +
+                        "'$name' task (current target is $jvmTarget) " +
-                            "jvm target compatibility should be set to the same Java version."
+                        "jvm target compatibility should be set to the same Java version.\n" +
-                    when (jvmTargetValidationMode.get()) {
+                        "Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain"
-                        PropertiesProvider.JvmTargetValidationMode.ERROR -> throw GradleException(errorMessage)
+                when (jvmTargetValidationMode.get()) {
-                        PropertiesProvider.JvmTargetValidationMode.WARNING -> logger.warn(errorMessage)
+                    PropertiesProvider.JvmTargetValidationMode.ERROR -> throw GradleException(errorMessage)
-                        else -> Unit
+                    PropertiesProvider.JvmTargetValidationMode.WARNING -> logger.warn(errorMessage)
-                    }
+                    else -> Unit
                 }
             }
         }

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/tasks/configuration/KotlinCompileConfig.kt

@@ -72,7 +72,6 @@ internal open class BaseKotlinCompileConfig<TASK : KotlinCompile> : AbstractKotl
             taskProvider.configure { task ->
                 javaTaskProvider?.let {
                     task.associatedJavaCompileTaskTargetCompatibility.value(javaTaskProvider.map { it.targetCompatibility })
-                    task.associatedJavaCompileTaskSources.from(javaTaskProvider.map { it.source })
                     task.associatedJavaCompileTaskName.value(javaTaskProvider.name)
                 }