Set jvm target validation to error only for builds with Gradle 8+

^KT54993 Fixed

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

@@ -13,6 +13,7 @@ import org.gradle.util.GradleVersion
 import org.jetbrains.kotlin.gradle.testbase.*
 import org.junit.jupiter.api.DisplayName
 import java.io.File
+import kotlin.io.path.appendText
 import kotlin.io.path.createDirectories
 import kotlin.io.path.deleteExisting
 import kotlin.io.path.writeText
@@ -32,10 +33,18 @@ class JvmTargetValidationTest : KGPBaseTest() {
             setJavaCompilationCompatibility(JavaVersion.VERSION_1_8)
             useToolchainToCompile(11)
 
+            gradleProperties.append(
+                """
+                kotlin.jvm.target.validation.mode = error
+                """.trimIndent()
+            )
+
             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.\n" +
+                            "By default will become an error since Gradle 8.0+! " +
+                            "Read more: https://kotl.in/gradle/jvm/target-validation\n" +
                             "Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain"
                 )
             }
@@ -62,8 +71,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
             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.\n" +
+                            "should be set to the same Java version.\n"
-                            "Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain"
                 )
             }
         }
@@ -106,6 +114,12 @@ class JvmTargetValidationTest : KGPBaseTest() {
         ) {
             useToolchainToCompile(11)
 
+            gradleProperties.append(
+                """
+                kotlin.jvm.target.validation.mode = error
+                """.trimIndent()
+            )
+
             build("build") {
                 assertOutputDoesNotContain(
                     "'compileJava' task (current target is 1.8) and 'compileKotlin' task (current target is 11) jvm target compatibility " +
@@ -183,6 +197,12 @@ class JvmTargetValidationTest : KGPBaseTest() {
                 """.trimIndent()
             )
 
+            gradleProperties.append(
+                """
+                kotlin.jvm.target.validation.mode = error
+                """.trimIndent()
+            )
+
             build("build")
         }
     }
@@ -197,6 +217,12 @@ class JvmTargetValidationTest : KGPBaseTest() {
             setJavaCompilationCompatibility(JavaVersion.VERSION_1_8)
             useToolchainToCompile(11)
 
+            gradleProperties.append(
+                """
+                kotlin.jvm.target.validation.mode = error
+                """.trimIndent()
+            )
+
             kotlinSourcesDir().toFile().deleteRecursively()
             javaSourcesDir().resolve("demo/HelloWorld.java").deleteExisting()
 
@@ -239,8 +265,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
             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" +
+                            "should be set to the same Java version.\n"
-                            "Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain"
                 )
             }
         }
@@ -309,6 +334,13 @@ class JvmTargetValidationTest : KGPBaseTest() {
             } else {
                 16
             }
+
+            gradleProperties.append(
+                """
+                kotlin.jvm.target.validation.mode = error
+                """.trimIndent()
+            )
+
             buildGradle.append(
                 """
                 
@@ -324,6 +356,37 @@ class JvmTargetValidationTest : KGPBaseTest() {
         }
     }
 
+    @DisplayName("Default value becomes 'error' with Gradle 8+")
+    @GradleTestVersions(maxVersion = TestVersions.Gradle.G_8_0)
+    @GradleTest
+    internal fun errorByDefaultWithGradle8(gradleVersion: GradleVersion) {
+        project("simple".fullProjectName, gradleVersion) {
+            //language=Groovy
+            buildGradle.appendText(
+                """
+                |
+                |tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile.class).configureEach {
+                |    compilerOptions.jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_11)
+                |}
+                """.trimMargin()
+            )
+
+            if (gradleVersion.baseVersion >= GradleVersion.version("8.0")) {
+                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."
+                    )
+                }
+            } else {
+                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."
+                    )
+                }
+            }
+        }
+    }
+
     private fun TestProject.setJavaCompilationCompatibility(
         target: JavaVersion
     ) {

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

@@ -19,6 +19,9 @@ interface TestVersions {
         const val G_7_3 = "7.3.3"
         const val G_7_4 = "7.4.2"
         const val G_7_5 = "7.5"
+        // https://gradle.org/nightly/
+        // Retention policy is 3 months
+        const val G_8_0 = "8.0-20221126231700+0000"
         const val MIN_SUPPORTED = minSupportedGradleVersion
         const val MIN_SUPPORTED_KPM = G_7_0
         const val MAX_SUPPORTED = G_7_3

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

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.gradle.plugin
 
 import org.gradle.api.Project
+import org.gradle.util.GradleVersion
 import org.jetbrains.kotlin.cli.common.CompilerSystemProperties
 import org.jetbrains.kotlin.cli.common.toBooleanLenient
 import org.jetbrains.kotlin.gradle.dsl.NativeCacheKind
@@ -424,7 +425,10 @@ internal class PropertiesProvider private constructor(private val project: Proje
     }
 
     val jvmTargetValidationMode: JvmTargetValidationMode
-        get() = enumProperty("kotlin.jvm.target.validation.mode", JvmTargetValidationMode.ERROR)
+        get() = enumProperty(
+            "kotlin.jvm.target.validation.mode",
+            if (GradleVersion.current().baseVersion >= GradleVersion.version("8.0")) JvmTargetValidationMode.ERROR else JvmTargetValidationMode.WARNING
+        )
 
     val kotlinDaemonJvmArgs: String?
         get() = this.property("kotlin.daemon.jvmargs")

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

@@ -23,6 +23,7 @@ import org.gradle.api.tasks.compile.AbstractCompile
 import org.gradle.api.tasks.compile.JavaCompile
 import org.gradle.api.tasks.util.PatternFilterable
 import org.gradle.api.tasks.util.PatternSet
+import org.gradle.util.GradleVersion
 import org.gradle.work.ChangeType
 import org.gradle.work.Incremental
 import org.gradle.work.InputChanges
@@ -644,7 +645,7 @@ abstract class KotlinCompile @Inject constructor(
     @get:Internal
     internal abstract val associatedJavaCompileTaskName: Property<String>
 
-    @get:Internal
+    @get:Input
     internal abstract val jvmTargetValidationMode: Property<PropertiesProvider.JvmTargetValidationMode>
 
     @get:Internal
@@ -794,10 +795,18 @@ abstract class KotlinCompile @Inject constructor(
             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 $jvmTarget) " +
+                val errorMessage = buildString {
-                        "jvm target compatibility should be set to the same Java version.\n" +
+                    append("'$javaTaskName' task (current target is $targetCompatibility) and ")
-                        "Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain"
+                    append("'$name' task (current target is $jvmTarget) ")
+                    appendLine("jvm target compatibility should be set to the same Java version.")
+                    if (GradleVersion.current().baseVersion < GradleVersion.version("8.0")) {
+                        append("By default will become an error since Gradle 8.0+! ")
+                        appendLine("Read more: https://kotl.in/gradle/jvm/target-validation")
+                    }
+                    appendLine("Consider using JVM toolchain: https://kotl.in/gradle/jvm/toolchain")
+                }
+
                 when (jvmTargetValidationMode.get()) {
                     PropertiesProvider.JvmTargetValidationMode.ERROR -> throw GradleException(errorMessage)
                     PropertiesProvider.JvmTargetValidationMode.WARNING -> logger.warn(errorMessage)