Support -Xuse-experimental in the new MPP languageSettings { ... } DSL

Add the corresponding Gradle plugin DSL, consistency checks, and logic
for propagating these settings to the compiler during build.

Issue #KT-26840 In Progress

libraries/tools/kotlin-gradle-plugin-api/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/LanguageSettingsBuilder.kt

@@ -15,4 +15,8 @@ interface LanguageSettingsBuilder {
     fun enableLanguageFeature(name: String)
 
     val enabledLanguageFeatures: Set<String>
+
+    fun useExperimentalAnnotation(name: String)
+
+    val experimentalAnnotationsInUse: Set<String>
 }

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

@@ -311,18 +311,29 @@ class NewMultiplatformIT : BaseGradleIT() {
 
         gradleBuildScript().appendText(
             "\n" + """
-                kotlin.sourceSets.jvm6Main.languageSettings {
+                kotlin.sourceSets.all {
-                    languageVersion = '1.3'
+                    it.languageSettings {
-                    apiVersion = '1.3'
+                        languageVersion = '1.3'
-                    enableLanguageFeature('InlineClasses')
+                        apiVersion = '1.3'
-                    progressiveMode = true
+                        enableLanguageFeature('InlineClasses')
+                        useExperimentalAnnotation('kotlin.ExperimentalUnsignedTypes')
+                        useExperimentalAnnotation('kotlin.contracts.ExperimentalContracts')
+                        progressiveMode = true
+                    }
                 }
             """.trimIndent()
         )
 
-        build("compileKotlinJvm6") {
+        listOf("compileKotlinJvm6", "compileKotlinNodeJs", "compileKotlin${nativeHostTargetName.capitalize()}").forEach {
-            assertSuccessful()
+            build(it) {
-            assertContains("-language-version 1.3", "-api-version 1.3", "-XXLanguage:+InlineClasses", " -progressive")
+                assertSuccessful()
+                assertTasksExecuted(":$it")
+                assertContains(
+                    "-language-version 1.3", "-api-version 1.3", "-XXLanguage:+InlineClasses",
+                    " -progressive", "-Xuse-experimental=kotlin.ExperimentalUnsignedTypes",
+                    "-Xuse-experimental=kotlin.contracts.ExperimentalContracts"
+                )
+            }
         }
     }
 
@@ -351,8 +362,20 @@ class NewMultiplatformIT : BaseGradleIT() {
             }
         }
 
-        testMonotonousCheck("languageSettings.languageVersion = '1.4'", SourceSetConsistencyChecks.languageVersionCheckHint)
+        testMonotonousCheck(
-        testMonotonousCheck("languageSettings.enableLanguageFeature('InlineClasses')", SourceSetConsistencyChecks.unstableFeaturesHint)
+            "languageSettings.languageVersion = '1.4'",
+            SourceSetConsistencyChecks.languageVersionCheckHint
+        )
+
+        testMonotonousCheck(
+            "languageSettings.enableLanguageFeature('InlineClasses')",
+            SourceSetConsistencyChecks.unstableFeaturesHint
+        )
+
+        testMonotonousCheck(
+            "languageSettings.useExperimentalAnnotation('kotlin.ExperimentalUnsignedTypes')",
+            SourceSetConsistencyChecks.experimentalAnnotationsInUseHint
+        )
 
         // check that enabling a bugfix feature and progressive mode or advancing API level
         // don't require doing the same for dependent source sets:
@@ -951,4 +974,4 @@ class NewMultiplatformIT : BaseGradleIT() {
             assertFileExists("foo/2.txt")
         }
     }
-}
+}

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

@@ -38,13 +38,20 @@ kotlin {
     }
 
     sourceSets {
+        commonMain {
+            dependencies {
+                api 'org.jetbrains.kotlin:kotlin-stdlib-common'
+            }
+        }
         jvm6Main {
             dependencies {
+                api 'org.jetbrains.kotlin:kotlin-stdlib'
                 implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:0.23.4'
             }
         }
         nodeJsMain {
         	dependencies {
+                api 'org.jetbrains.kotlin:kotlin-stdlib-js'
         		implementation 'org.jetbrains.kotlinx:kotlinx-html-js:0.6.11'
         	}
         }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/sources/DefaultLanguageSettingsBuilder.kt

@@ -50,6 +50,14 @@ internal class DefaultLanguageSettingsBuilder : LanguageSettingsBuilder {
         enabledLanguageFeaturesImpl += languageFeature
     }
 
+    private val experimentalAnnotationsInUseImpl = mutableSetOf<String>()
+
+    override val experimentalAnnotationsInUse: Set<String> = experimentalAnnotationsInUseImpl
+
+    override fun useExperimentalAnnotation(name: String) {
+        experimentalAnnotationsInUseImpl += name
+    }
+
     companion object {
     }
 }
@@ -68,6 +76,10 @@ internal fun applyLanguageSettingsToKotlinTask(
     languageSettingsBuilder.enabledLanguageFeatures.forEach { featureName ->
         freeCompilerArgs += "-XXLanguage:+$featureName"
     }
+
+    languageSettingsBuilder.experimentalAnnotationsInUse.forEach { annotationName ->
+        freeCompilerArgs += "-Xuse-experimental=$annotationName"
+    }
 }
 
 private val apiVersionValues = ApiVersion.run { listOf(KOTLIN_1_0, KOTLIN_1_1, KOTLIN_1_2, KOTLIN_1_3) }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/sources/SourceSetConsistencyChecker.kt

@@ -44,6 +44,15 @@ object SourceSetConsistencyChecks {
         leftExtendsRightConsistently = { left, right -> left.containsAll(right) },
         consistencyConditionHint = unstableFeaturesHint
     )
+
+    const val experimentalAnnotationsInUseHint = "The dependent source set must use all experimental annotations that its dependency uses."
+
+    internal val experimentalAnnotationsCheck = ConsistencyCheck<KotlinSourceSet, Set<String>>(
+        name = "set of experimental annotations in use",
+        getValue = { sourceSet -> sourceSet.languageSettings.experimentalAnnotationsInUse },
+        leftExtendsRightConsistently = { left, right -> left.containsAll(right) },
+        consistencyConditionHint = experimentalAnnotationsInUseHint
+    )
 }
 
 internal class SourceSetConsistencyChecker(
@@ -76,5 +85,5 @@ internal class SourceSetConsistencyChecker(
 
 internal val defaultSourceSetLanguageSettingsChecker = with(SourceSetConsistencyChecks) {
     // We don't check the progressive mode, since the features it enables are bugfixes
-    SourceSetConsistencyChecker(listOf(languageVersionCheck, unstableFeaturesCheck))
+    SourceSetConsistencyChecker(listOf(languageVersionCheck, experimentalAnnotationsCheck, unstableFeaturesCheck))
 }

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

@@ -5,7 +5,6 @@ import org.gradle.api.DefaultTask
 import org.gradle.api.Project
 import org.gradle.api.file.FileCollection
 import org.gradle.api.file.FileTree
-import org.gradle.api.provider.Property
 import org.gradle.api.provider.Provider
 import org.gradle.api.tasks.*
 import org.gradle.api.tasks.compile.AbstractCompile
@@ -21,10 +20,7 @@ import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeCompilation
 import org.jetbrains.kotlin.gradle.plugin.mpp.defaultSourceSetName
 import org.jetbrains.kotlin.gradle.plugin.mpp.isMainCompilation
 import org.jetbrains.kotlin.konan.target.CompilerOutputKind
-import org.jetbrains.kotlin.konan.target.CompilerOutputKind.DYNAMIC
+import org.jetbrains.kotlin.konan.target.CompilerOutputKind.*
-import org.jetbrains.kotlin.konan.target.CompilerOutputKind.FRAMEWORK
-import org.jetbrains.kotlin.konan.target.CompilerOutputKind.PROGRAM
-import org.jetbrains.kotlin.konan.target.CompilerOutputKind.STATIC
 import org.jetbrains.kotlin.konan.target.KonanTarget
 import java.io.File
 
@@ -154,6 +150,9 @@ open class KotlinNativeCompile : AbstractCompile() {
 
     val enabledLanguageFeatures: Set<String>
         @Input get() = languageSettings?.enabledLanguageFeatures ?: emptySet()
+
+    val experimentalAnnotationsInUse: Set<String>
+        @Input get() = languageSettings?.experimentalAnnotationsInUse.orEmpty()
     // endregion.
 
     // region DSL for compiler options
@@ -227,6 +226,9 @@ open class KotlinNativeCompile : AbstractCompile() {
         enabledLanguageFeatures.forEach { featureName ->
             add("-XXLanguage:+$featureName")
         }
+        experimentalAnnotationsInUse.forEach { annotationName ->
+            add("-Xuse-experimental=$annotationName")
+        }
 
         // Compiler plugins.
         compilerPluginClasspath?.let { pluginClasspath ->