Introduce language version 2.0 and associate K2 compiler with it

2022-11-28 18:20:10 +01:00
parent afe1150aec
commit 3dc05f4ec5
84 changed files with 233 additions and 151 deletions
@@ -453,6 +453,7 @@ class GenerationState private constructor(
            this[KOTLIN_1_7] = JvmMetadataVersion(1, 7, 0)
            this[KOTLIN_1_8] = JvmMetadataVersion.INSTANCE
            this[KOTLIN_1_9] = JvmMetadataVersion(1, 9, 0)
+            this[KOTLIN_2_0] = JvmMetadataVersion(2, 0, 0)

            check(size == LanguageVersion.values().size) {
                "Please add mappings from the missing LanguageVersion instances to the corresponding JvmMetadataVersion " +
@@ -643,7 +643,7 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
        }
    }

-    private fun checkLanguageVersionIsStable(languageVersion: LanguageVersion, collector: MessageCollector) {
+    fun checkLanguageVersionIsStable(languageVersion: LanguageVersion, collector: MessageCollector) {
        if (!languageVersion.isStable && !suppressVersionWarnings) {
            collector.report(
                CompilerMessageSeverity.STRONG_WARNING,
@@ -573,7 +573,7 @@ Also sets `-jvm-target` value equal to the selected JDK version"""
        result[JvmAnalysisFlags.sanitizeParentheses] = sanitizeParentheses
        result[JvmAnalysisFlags.suppressMissingBuiltinsError] = suppressMissingBuiltinsError
        result[JvmAnalysisFlags.enableJvmPreview] = enableJvmPreview
-        result[AnalysisFlags.allowUnstableDependencies] = allowUnstableDependencies || useK2
+        result[AnalysisFlags.allowUnstableDependencies] = allowUnstableDependencies || useK2 || languageVersion.usesK2
        result[JvmAnalysisFlags.disableUltraLightClasses] = disableUltraLightClasses
        result[JvmAnalysisFlags.useIR] = !useOldBackend
        return result
@@ -175,14 +175,15 @@ public class K2JSCompiler extends CLICompiler<K2JSCompilerArguments> {

        ExitCode exitCode = OK;

-        if (K2JSCompilerArgumentsKt.isIrBackendEnabled(arguments)) {
+        LanguageVersionSettings languageVersionSettings = CommonConfigurationKeysKt.getLanguageVersionSettings(configuration);
+        LanguageVersion languageVersion = languageVersionSettings.getLanguageVersion();
+        if (K2JSCompilerArgumentsKt.isIrBackendEnabled(arguments) || languageVersion.getUsesK2()) {
            exitCode = getIrCompiler().doExecute(arguments, configuration.copy(), rootDisposable, paths);
        }
-        if (K2JSCompilerArgumentsKt.isPreIrBackendDisabled(arguments)) {
+        if (K2JSCompilerArgumentsKt.isPreIrBackendDisabled(arguments) || languageVersion.getUsesK2()) {
            return exitCode;
        }

-        LanguageVersionSettings languageVersionSettings = CommonConfigurationKeysKt.getLanguageVersionSettings(configuration);

        if (CompilerSystemProperties.KOTLIN_JS_COMPILER_LEGACY_FORCE_ENABLED.getValue() != "true" && languageVersionSettings.getLanguageVersion().compareTo(LanguageVersion.KOTLIN_1_9) >= 0) {
            messageCollector.report(ERROR, "Old Kotlin/JS compiler is no longer supported. Please migrate to the new JS IR backend", null);
@@ -287,11 +287,7 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
            val outputKlibPath =
                if (arguments.irProduceKlibFile) outputDir.resolve("$outputName.klib").normalize().absolutePath
                else outputDirPath
-            if (arguments.useK2) {
-                messageCollector.report(
-                    STRONG_WARNING,
-                    "ATTENTION!\n This build uses experimental K2 compiler: \n  -Xuse-k2"
-                )
+            if (configuration.get(CommonConfigurationKeys.USE_FIR) == true) {
                sourceModule = processSourceModuleWithK2(environmentForJS, libraries, friendLibraries, arguments, outputKlibPath)
            } else {
                sourceModule = processSourceModule(environmentForJS, libraries, friendLibraries, arguments, outputKlibPath)
@@ -31,8 +31,7 @@ import org.jetbrains.kotlin.cli.jvm.plugins.PluginCliParser
 import org.jetbrains.kotlin.cli.plugins.processCompilerPluginsOptions
 import org.jetbrains.kotlin.compiler.plugin.CommandLineProcessor
 import org.jetbrains.kotlin.compiler.plugin.ComponentRegistrar
-import org.jetbrains.kotlin.config.CompilerConfiguration
-import org.jetbrains.kotlin.config.Services
+import org.jetbrains.kotlin.config.*
 import org.jetbrains.kotlin.ir.util.IrMessageLogger
 import org.jetbrains.kotlin.metadata.deserialization.BinaryVersion
 import org.jetbrains.kotlin.progress.CompilationCanceledException
@@ -77,7 +76,7 @@ abstract class CLICompiler<A : CommonCompilerArguments> : CLITool<A>() {
        configuration.put(CLIConfigurationKeys.ORIGINAL_MESSAGE_COLLECTOR_KEY, messageCollector)

        val collector = GroupingMessageCollector(messageCollector, arguments.allWarningsAsErrors).also {
-            configuration.put(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY, it)
+            configuration.put(MESSAGE_COLLECTOR_KEY, it)
        }

        configuration.put(IrMessageLogger.IR_MESSAGE_LOGGER, IrMessageCollector(collector))
@@ -88,7 +87,7 @@ abstract class CLICompiler<A : CommonCompilerArguments> : CLITool<A>() {
            setupPlatformSpecificArgumentsAndServices(configuration, arguments, services)
            val paths = computeKotlinPaths(collector, arguments)
            if (collector.hasErrors()) {
-                return ExitCode.COMPILATION_ERROR
+                return COMPILATION_ERROR
            }

            val canceledStatus = services[CompilationCanceledStatus::class.java]
@@ -98,6 +97,36 @@ abstract class CLICompiler<A : CommonCompilerArguments> : CLITool<A>() {
            try {
                setIdeaIoUseFallback()

+                val useK2FromFlag = arguments.useK2
+                val languageVersion = configuration.languageVersionSettings.languageVersion
+                if (useK2FromFlag) {
+                    when {
+                        arguments.languageVersion == null -> {
+                            messageCollector.report(
+                                STRONG_WARNING,
+                                "Compiler flag -Xuse-k2 is deprecated, please use -language-version 2.0 instead"
+                            )
+                        }
+                        languageVersion.usesK2 -> {
+                            messageCollector.report(
+                                STRONG_WARNING,
+                                "Compiler flag -Xuse-k2 is redundant"
+                            )
+                        }
+                        else -> {
+                            messageCollector.report(
+                                STRONG_WARNING,
+                                "With -Xuse-k2 compiler flag -language-version $languageVersion has no effect, please remove -Xuse-k2 flag or use -language-version 2.0 instead"
+                            )
+                        }
+                    }
+                    if (!languageVersion.usesK2) {
+                        val languageVersionSettings = configuration.languageVersionSettings
+                        configuration.languageVersionSettings = languageVersionSettings.copy(LanguageVersion.KOTLIN_2_0)
+                        arguments.checkLanguageVersionIsStable(LanguageVersion.KOTLIN_2_0, messageCollector)
+                    }
+                }
+
                val code = doExecute(arguments, configuration, rootDisposable, paths)

                performanceManager.notifyCompilationFinished()
@@ -115,12 +144,12 @@ abstract class CLICompiler<A : CommonCompilerArguments> : CLITool<A>() {
                return if (collector.hasErrors()) COMPILATION_ERROR else code
            } catch (e: CompilationCanceledException) {
                collector.reportCompilationCancelled(e)
-                return ExitCode.OK
+                return OK
            } catch (e: RuntimeException) {
                val cause = e.cause
                if (cause is CompilationCanceledException) {
                    collector.reportCompilationCancelled(cause)
-                    return ExitCode.OK
+                    return OK
                } else {
                    throw e
                }
@@ -22,8 +22,6 @@ fun <A : CommonCompilerArguments> CompilerConfiguration.setupCommonArguments(
    createMetadataVersion: ((IntArray) -> BinaryVersion)? = null
 ) {
    put(CommonConfigurationKeys.DISABLE_INLINE, arguments.noInline)
-    put(CommonConfigurationKeys.USE_FIR, arguments.useK2)
-    put(CommonConfigurationKeys.USE_LIGHT_TREE, arguments.useFirLT)
    put(CommonConfigurationKeys.USE_FIR_EXTENDED_CHECKERS, arguments.useFirExtendedCheckers)
    put(CommonConfigurationKeys.EXPECT_ACTUAL_LINKER, arguments.expectActualLinker)
    putIfNotNull(CLIConfigurationKeys.INTELLIJ_PLUGIN_ROOT, arguments.intellijPluginRoot)
@@ -45,6 +43,10 @@ fun <A : CommonCompilerArguments> CompilerConfiguration.setupCommonArguments(
    }

    setupLanguageVersionSettings(arguments)
+
+    val usesK2 = arguments.useK2 || languageVersionSettings.languageVersion.usesK2
+    put(CommonConfigurationKeys.USE_FIR, usesK2)
+    put(CommonConfigurationKeys.USE_LIGHT_TREE, usesK2)
 }

 fun <A : CommonCompilerArguments> CompilerConfiguration.setupLanguageVersionSettings(arguments: A) {
@@ -75,11 +75,6 @@ object FirKotlinToJvmBytecodeCompiler {
    ): Boolean {
        val performanceManager = projectConfiguration.get(CLIConfigurationKeys.PERF_MANAGER)

-        messageCollector.report(
-            STRONG_WARNING,
-            "ATTENTION!\n This build uses experimental K2 compiler: \n  -Xuse-k2"
-        )
-
        val notSupportedPlugins = mutableListOf<String?>().apply {
            projectConfiguration.get(ComponentRegistrar.PLUGIN_COMPONENT_REGISTRARS).collectIncompatiblePluginNamesTo(this, ComponentRegistrar::supportsK2)
            projectConfiguration.get(CompilerPluginRegistrar.COMPILER_PLUGIN_REGISTRARS).collectIncompatiblePluginNamesTo(this, CompilerPluginRegistrar::supportsK2)
@@ -89,9 +84,9 @@ object FirKotlinToJvmBytecodeCompiler {
            messageCollector.report(
                CompilerMessageSeverity.ERROR,
                """
-                    |There are some plugins incompatible with K2 compiler:
+                    |There are some plugins incompatible with language version 2.0:
                    |${notSupportedPlugins.joinToString(separator = "\n|") { "  $it" }}
-                    |Please remove -Xuse-k2
+                    |Please use language version 1.* (e.g. 1.9)
                """.trimMargin()
            )
            return false
@@ -99,11 +99,6 @@ fun compileModulesUsingFrontendIrAndLightTree(

    performanceManager?.notifyCompilerInitialized(0, 0, targetDescription)

-    messageCollector.report(
-        CompilerMessageSeverity.STRONG_WARNING,
-        "ATTENTION!\n This build uses experimental K2 compiler: \n  -Xuse-k2"
-    )
-
    val outputs = mutableListOf<GenerationState>()
    var mainClassFqName: FqName? = null

@@ -260,7 +260,7 @@ fun CompilerConfiguration.configureAdvancedJvmOptions(arguments: K2JVMCompilerAr

    // TODO: ignore previous configuration value when we do not need old backend in scripting by default
    val useOldBackend = arguments.useOldBackend || (!arguments.useIR && get(JVMConfigurationKeys.IR) == false)
-    val useIR = arguments.useK2 ||
+    val useIR = arguments.useK2 || languageVersionSettings.languageVersion.usesK2 ||
            if (languageVersionSettings.supportsFeature(LanguageFeature.JvmIrEnabledByDefault)) {
                !useOldBackend
            } else {
@@ -59,7 +59,7 @@ class K2MetadataCompiler : CLICompiler<K2MetadataCompilerArguments>() {
    ): ExitCode {
        val collector = configuration.getNotNull(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY)
        if (configuration.getBoolean(CommonConfigurationKeys.USE_FIR)) {
-            collector.report(ERROR, "K2 does not support compilation to metadata right now")
+            collector.report(ERROR, "Compilation to metadata is not supported in language version 2.0 right now")
            return ExitCode.COMPILATION_ERROR
        }
        val performanceManager = configuration.getNotNull(CLIConfigurationKeys.PERF_MANAGER)
@@ -108,6 +108,8 @@ object FirSessionFactoryHelper {

                    override fun <T> getFlag(flag: AnalysisFlag<T>): T = stub()

+                    override fun copy(languageVersion: LanguageVersion): LanguageVersionSettings = this
+
                    override val apiVersion: ApiVersion
                        get() = stub()
                    override val languageVersion: LanguageVersion
@@ -1,5 +1,6 @@
 $TESTDATA_DIR$/fir.kt
-Xuse-k2
+-language-version
+2.0
 -ir-output-dir
 $TEMP_DIR$
 -ir-output-name
@@ -1,4 +1,2 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 OK
@@ -1,3 +1,3 @@
 error: unknown API version: 239.42
-Supported API versions: 1.3 (deprecated), 1.4 (deprecated), 1.5, 1.6, 1.7, 1.8, 1.9 (experimental)
+Supported API versions: 1.3 (deprecated), 1.4 (deprecated), 1.5, 1.6, 1.7, 1.8, 1.9 (experimental), 2.0 (experimental)
 COMPILATION_ERROR
@@ -1,4 +1,5 @@
 $TESTDATA_DIR$/conflictingJvmDeclarations.kt
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/conflictingJvmDeclarations.kt:2:5: error: platform declaration clash: The following declarations have the same JVM signature (getX()I):
    fun `<get-x>`(): Int defined in Foo
    fun getX(): Int defined in Foo
@@ -1,4 +1,5 @@
 $TESTDATA_DIR$/conflictingProjection.kt
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/conflictingProjection.kt:10:19: error: projection is conflicting with variance of the corresponding type parameter of Out<in kotlin/Int>. Remove the projection or replace it with '*'
 fun a8(value: Out<in Int>) {}
                  ^
@@ -1,5 +1,6 @@
 $TESTDATA_DIR$/extendedCheckers.kt
-Xuse-k2
+-language-version
+2.0
 -Xuse-fir-extended-checkers
 -d
 $TEMP_DIR$
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/extendedCheckers.kt:2:12: warning: redundant explicit type
    val i: Int = 1
           ^
@@ -1,5 +1,6 @@
 $TESTDATA_DIR$/extendedCheckersNoWarning.kt
-Xuse-k2
+-language-version
+2.0
 -Xuse-fir-extended-checkers
 -d
 $TEMP_DIR$
@@ -1,4 +1,2 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 OK
@@ -1,5 +1,6 @@
 $TESTDATA_DIR$/firDeprecationJava.kt
 $TESTDATA_DIR$/firDeprecationJava
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/firDeprecationJava.kt:3:12: warning: '@Deprecated(...) fun stop(): Unit
 ' is deprecated. Deprecated in Java
    thread.stop()
@@ -1,4 +1,5 @@
 $TESTDATA_DIR$/firDfa.kt
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,4 +1,5 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+compiler/testData/cli/jvm/firDfa.kt:3:10: warning: unnecessary non-null assertion (!!) on a non-null receiver of type kotlin/String
+        x!!.length
+         ^
 OK
@@ -1,4 +1,5 @@
 $TESTDATA_DIR$/firError.kt
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/firError.kt:1:13: error: 'val' on function parameter is not allowed
 fun println(val x: Int) {}
            ^
@@ -1,4 +1,3 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: compiler flag -Xuse-k2 is deprecated, please use -language-version 2.0 instead
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 OK
@@ -0,0 +1,5 @@
+$TESTDATA_DIR$/firHello20.kt
+-language-version
+2.0
+-d
+$TEMP_DIR$
@@ -0,0 +1 @@
+fun main() {}
@@ -0,0 +1,2 @@
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+OK
@@ -0,0 +1,6 @@
+$TESTDATA_DIR$/firHello20.kt
+-Xuse-k2
+-language-version
+2.0
+-d
+$TEMP_DIR$
@@ -0,0 +1,3 @@
+warning: compiler flag -Xuse-k2 is redundant
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+OK
@@ -0,0 +1,6 @@
+$TESTDATA_DIR$/firHello20.kt
+-Xuse-k2
+-language-version
+1.5
+-d
+$TEMP_DIR$
@@ -0,0 +1,3 @@
+warning: with -Xuse-k2 compiler flag -language-version 1.5 has no effect, please remove -Xuse-k2 flag or use -language-version 2.0 instead
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+OK
@@ -2,7 +2,8 @@ $TESTDATA_DIR$/firMultiplatformCompilationWithError/common.kt
 $TESTDATA_DIR$/firMultiplatformCompilationWithError/jvm.kt
 -Xcommon-sources
 $TESTDATA_DIR$/firMultiplatformCompilationWithError/common.kt
-Xuse-k2
+-language-version
+2.0
 -cp
 .
 -d
@@ -8,9 +8,7 @@ This mode is not recommended for production use,
 as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!

-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/firMultiplatformCompilationWithError/jvm.kt:1:18: error: actual class 'actual  interface A : Any' has no corresponding members for expected class members:

    expect fun foo(): Unit
@@ -8,7 +8,6 @@ This mode is not recommended for production use,
 as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!

-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: compiler flag -Xuse-k2 is deprecated, please use "-language-version 2.0" instead
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 OK
@@ -2,7 +2,8 @@ $TESTDATA_DIR$/firMultiplatformCompilationWithoutErrors/common.kt
 $TESTDATA_DIR$/firMultiplatformCompilationWithoutErrors/jvm.kt
 -Xcommon-sources
 $TESTDATA_DIR$/firMultiplatformCompilationWithoutErrors/common.kt
-Xuse-k2
+-language-version
+2.0
 -cp
 .
 -d
@@ -8,7 +8,5 @@ This mode is not recommended for production use,
 as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!

-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 OK
@@ -1,5 +1,6 @@
 $TESTDATA_DIR$/firStdlibDependency.kt
-Xuse-k2
+-language-version
+2.0
 -cp
 .
 -d
@@ -1,4 +1,2 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 OK
@@ -1,6 +1,7 @@
 $TESTDATA_DIR$/firVsClassicAnnotation.kt
 -classpath
 $TESTDATA_DIR$/firVsClassicAnnotation
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,4 +1,2 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 OK
@@ -1,4 +1,5 @@
 $TESTDATA_DIR$/inapplicableLateinitModifier.kt
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/inapplicableLateinitModifier.kt:6:1: error: 'lateinit' modifier is not allowed on delegated properties
 lateinit var kest by Delegate
 ^
@@ -1,4 +1,5 @@
 $TESTDATA_DIR$/instanceAccessBeforeSuperCall.kt
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/instanceAccessBeforeSuperCall.kt:2:26: error: unresolved reference: getSomeInt
    constructor(x: Int = getSomeInt(), other: A = this, header: String = keker) {}
                         ^
@@ -1,3 +1,3 @@
 error: unknown language version: 239.42
-Supported language versions: 1.3 (deprecated), 1.4 (deprecated), 1.5, 1.6, 1.7, 1.8, 1.9 (experimental)
+Supported language versions: 1.3 (deprecated), 1.4 (deprecated), 1.5, 1.6, 1.7, 1.8, 1.9 (experimental), 2.0 (experimental)
 COMPILATION_ERROR
@@ -2,5 +2,6 @@ $TESTDATA_DIR$/optInEmptyMessageFir.kt
 -d
 $TEMP_DIR$
 -opt-in=kotlin.RequiresOptIn
-Xuse-k2
+-language-version
+2.0

@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/optInEmptyMessageFir.kt:8:5: error: this declaration needs opt-in. Its usage must be marked with '@EmptyMarker' or '@OptIn(EmptyMarker::class)'
    foo()
    ^
@@ -2,4 +2,5 @@ $TESTDATA_DIR$/optInOverrideMessageFir.kt
 -d
 $TEMP_DIR$
 -opt-in=kotlin.RequiresOptIn
-Xuse-k2
+-language-version
+2.0
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/optInOverrideMessageFir.kt:16:18: error: base declaration of supertype 'Base' needs opt-in. This API is experimental and can change at any time, please use with care. The declaration override must be annotated with '@Marker' or '@OptIn(Marker::class)'
    override fun foo() {}
                 ^
@@ -1,5 +1,6 @@
 -d
 $TEMP_DIR$
-Xuse-k2
+-language-version
+2.0
 -Xcompiler-plugin=dist/kotlinc/lib/allopen-compiler-plugin.jar=annotation=foo.AllOpen
 $TESTDATA_DIR$/firAllOpenPlugin.kt
@@ -1,5 +1,3 @@
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 warning: argument -Xcompiler-plugin is experimental
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
 OK
@@ -1,8 +1,8 @@
 -d
 $TEMP_DIR$
 -Xcompiler-plugin=dist/kotlinc/lib/noarg-compiler-plugin.jar=annotation=foo.NoArg
-Xuse-k2
-
+-language-version
+2.0
 -Xplugin=dist/kotlinc/lib/allopen-compiler-plugin.jar
 -P
 plugin\:org.jetbrains.kotlin.allopen\:annotation=foo.AllOpen
@@ -1,3 +1,4 @@
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 error: mixing legacy and modern plugin arguments is prohibited. Please use only one syntax
 Legacy arguments:
  -Xplugin=dist/kotlinc/lib/allopen-compiler-plugin.jar
@@ -1,5 +1,6 @@
 -d
 $TEMP_DIR$
-Xuse-k2
+-language-version
+2.0
 -Xcompiler-plugin=dist/kotlinc/lib/allopen-compiler-plugin.jar=annotation=foo.AllOpen1,annotation=foo.AllOpen2
 $TESTDATA_DIR$/multipleOptionsForOnePlugin.kt
@@ -1,5 +1,3 @@
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 warning: argument -Xcompiler-plugin is experimental
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
 OK
@@ -1,6 +1,7 @@
 -d
 $TEMP_DIR$
-Xuse-k2
+-language-version
+2.0
 -Xcompiler-plugin=dist/kotlinc/lib/allopen-compiler-plugin.jar=annotation=foo.AllOpen
 -Xcompiler-plugin=dist/kotlinc/lib/noarg-compiler-plugin.jar=annotation=foo.NoArg
 $TESTDATA_DIR$/multiplePlugins.kt
@@ -1,6 +1,4 @@
-warning: ATTENTION!
- This build uses experimental K2 compiler:
-  -Xuse-k2
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 compiler/testData/cli/jvm/plugins/multiplePlugins.kt:11:17: error:
    inner class Inner(val s: String)
                ^
@@ -1,5 +1,6 @@
 -d
 $TEMP_DIR$
-Xuse-k2
+-language-version
+2.0
 -Xcompiler-plugin=dist/kotlinc/lib/allopen-compiler-plugin.jar,dist/kotlinc/lib/noarg-compiler-plugin.jar=annotation=foo.AllOpen
 $TESTDATA_DIR$/multiplePluginsInSameArg.kt
@@ -1,3 +1,4 @@
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 error: multiple plugins found in given classpath: org.jetbrains.kotlin.allopen.AllOpenComponentRegistrar, org.jetbrains.kotlin.noarg.NoArgComponentRegistrar
  Plugin configuration is: dist/kotlinc/lib/allopen-compiler-plugin.jar,dist/kotlinc/lib/noarg-compiler-plugin.jar=annotation=foo.AllOpen
 COMPILATION_ERROR
@@ -1,5 +1,6 @@
 -d
 $TEMP_DIR$
-Xuse-k2
+-language-version
+2.0
 -Xcompiler-plugin=dist/kotlinc/lib/kotlin-reflect.jar
 $TESTDATA_DIR$/noPluginInClasspath.kt
@@ -1,2 +1,3 @@
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
 error: no plugins found in given classpath: dist/kotlinc/lib/kotlin-reflect.jar
 COMPILATION_ERROR
@@ -1,4 +1,5 @@
 $TESTDATA_DIR$/fir.kt
-Xuse-k2
+-language-version
+2.0
 -d
 $TEMP_DIR$
@@ -1,2 +1,3 @@
-error: k2 does not support compilation to metadata right now
+warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+error: compilation to metadata is not supported in language version 2.0 right now
 COMPILATION_ERROR
@@ -1,8 +1,10 @@
-error: classes compiled by the new Kotlin compiler frontend were found in dependencies. Remove them from the classpath or use '-Xallow-unstable-dependencies' to suppress errors
-compiler/testData/compileKotlinAgainstCustomBinaries/oldJvmAgainstFir/source.kt:4:5: error: class 'lib.AKt' is compiled by the new Kotlin compiler frontend and cannot be loaded by the old compiler
+error: incompatible classes were found in dependencies. Remove them from the classpath or use '-Xskip-metadata-version-check' to suppress errors
+$TMP_DIR$/library.jar!/META-INF/main.kotlin_module: error: module was compiled with an incompatible version of Kotlin. The binary version of its metadata is 2.0.0, expected version is $ABI_VERSION$.
+compiler/testData/compileKotlinAgainstCustomBinaries/oldJvmAgainstFir/source.kt:4:5: error: unresolved reference: get
    get { Box("OK").value }
    ^
-compiler/testData/compileKotlinAgainstCustomBinaries/oldJvmAgainstFir/source.kt:4:11: error: class 'lib.Box' is compiled by the new Kotlin compiler frontend and cannot be loaded by the old compiler
+compiler/testData/compileKotlinAgainstCustomBinaries/oldJvmAgainstFir/source.kt:4:11: error: class 'lib.Box' was compiled with an incompatible version of Kotlin. The binary version of its metadata is 2.0.0, expected version is $ABI_VERSION$.
+The class is loaded from $TMP_DIR$/library.jar!/lib/Box.class
    get { Box("OK").value }
          ^
 COMPILATION_ERROR
@@ -26,19 +26,23 @@ const val SANITIZE_PARENTHESES = "SANITIZE_PARENTHESES"
 const val ENABLE_JVM_PREVIEW = "ENABLE_JVM_PREVIEW"

 data class CompilerTestLanguageVersionSettings(
-        private val initialLanguageFeatures: Map<LanguageFeature, LanguageFeature.State>,
-        override val apiVersion: ApiVersion,
-        override val languageVersion: LanguageVersion,
-        val analysisFlags: Map<AnalysisFlag<*>, Any?> = emptyMap()
+    private val initialLanguageFeatures: Map<LanguageFeature, LanguageFeature.State>,
+    override val apiVersion: ApiVersion,
+    override val languageVersion: LanguageVersion,
+    val analysisFlags: Map<AnalysisFlag<*>, Any?> = emptyMap()
 ) : LanguageVersionSettings {
    val extraLanguageFeatures = specificFeaturesForTests() + initialLanguageFeatures
    private val delegate = LanguageVersionSettingsImpl(languageVersion, apiVersion, emptyMap(), extraLanguageFeatures)

    override fun getFeatureSupport(feature: LanguageFeature): LanguageFeature.State =
-            extraLanguageFeatures[feature] ?: delegate.getFeatureSupport(feature)
+        extraLanguageFeatures[feature] ?: delegate.getFeatureSupport(feature)

    override fun isPreRelease(): Boolean = false

+    override fun copy(languageVersion: LanguageVersion): LanguageVersionSettings {
+        return CompilerTestLanguageVersionSettings(initialLanguageFeatures, apiVersion, languageVersion, analysisFlags)
+    }
+
    @Suppress("UNCHECKED_CAST")
    override fun <T> getFlag(flag: AnalysisFlag<T>): T = analysisFlags[flag] as T? ?: flag.defaultValue
 }
@@ -138,7 +138,7 @@ abstract class AbstractKotlinCompilerIntegrationTest : TestCaseWithTmpdir() {

    private fun String.removeFirWarning(): String {
        return this.replace(
-            "warning: ATTENTION!\n This build uses experimental K2 compiler: \n  -Xuse-k2\n", ""
+            "warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features\n", ""
        )
    }

@@ -447,6 +447,21 @@ public class CliTestGenerated extends AbstractCliTest {
            runTest("compiler/testData/cli/jvm/firHello.args");
        }

+        @TestMetadata("firHello20.args")
+        public void testFirHello20() throws Exception {
+            runTest("compiler/testData/cli/jvm/firHello20.args");
+        }
+
+        @TestMetadata("firHello20WithFlag.args")
+        public void testFirHello20WithFlag() throws Exception {
+            runTest("compiler/testData/cli/jvm/firHello20WithFlag.args");
+        }
+
+        @TestMetadata("firHello20WithOldLV.args")
+        public void testFirHello20WithOldLV() throws Exception {
+            runTest("compiler/testData/cli/jvm/firHello20WithOldLV.args");
+        }
+
        @TestMetadata("firMultiplatformCompilationWithError.args")
        public void testFirMultiplatformCompilationWithError() throws Exception {
            runTest("compiler/testData/cli/jvm/firMultiplatformCompilationWithError.args");
@@ -406,7 +406,7 @@ class CompileKotlinAgainstCustomBinariesTest : AbstractKotlinCompilerIntegration

            // Starting from Kotlin 1.4, major.minor version of JVM metadata must be equal to the language version.
            // From Kotlin 1.0 to 1.4, we used JVM metadata version 1.1.*.
-            val expectedMajor = 1
+            val expectedMajor = if (languageVersion.usesK2) 2 else 1
            val expectedMinor = if (languageVersion < LanguageVersion.KOTLIN_1_4) 1 else languageVersion.minor

            val topLevelClass = LocalFileKotlinClass.create(File(tmpdir.absolutePath, "Foo.class"))!!
@@ -563,7 +563,7 @@ class CompileKotlinAgainstCustomBinariesTest : AbstractKotlinCompilerIntegration

    fun testInternalFromFriendModuleFir() {
        val library = compileLibrary("library")
-        compileKotlin("source.kt", tmpdir, listOf(library), additionalOptions = listOf("-Xfriend-paths=${library.path}", "-Xuse-k2"))
+        compileKotlin("source.kt", tmpdir, listOf(library), additionalOptions = listOf("-Xfriend-paths=${library.path}", "-language-version", "2.0"))
    }

    fun testJvmDefaultClashWithOld() {
@@ -642,20 +642,20 @@ class CompileKotlinAgainstCustomBinariesTest : AbstractKotlinCompilerIntegration
    }

    fun testFirAgainstFir() {
-        val library = compileLibrary("library", additionalOptions = listOf("-Xuse-k2"))
-        compileKotlin("source.kt", tmpdir, listOf(library), additionalOptions = listOf("-Xuse-k2"))
+        val library = compileLibrary("library", additionalOptions = listOf("-language-version", "2.0"))
+        compileKotlin("source.kt", tmpdir, listOf(library), additionalOptions = listOf("-language-version", "2.0"))
    }

    fun testFirAgainstOldJvm() {
        val library = compileLibrary("library")
-        compileKotlin("source.kt", tmpdir, listOf(library), additionalOptions = listOf("-Xuse-k2"))
+        compileKotlin("source.kt", tmpdir, listOf(library), additionalOptions = listOf("-language-version", "2.0"))
    }

    fun testFirIncorrectJavaSignature() {
        compileKotlin(
            "source.kt", tmpdir,
            listOf(),
-            additionalOptions = listOf("-Xuse-k2"),
+            additionalOptions = listOf("-language-version", "2.0"),
            additionalSources = listOf("A.java", "B.java"),
        )
    }
@@ -664,7 +664,7 @@ class CompileKotlinAgainstCustomBinariesTest : AbstractKotlinCompilerIntegration
        compileKotlin(
            "source.kt", tmpdir,
            listOf(),
-            additionalOptions = listOf("-Xuse-k2"),
+            additionalOptions = listOf("-language-version", "2.0"),
            additionalSources = listOf("A.java", "B.java"),
        )
    }
@@ -678,10 +678,10 @@ class CompileKotlinAgainstCustomBinariesTest : AbstractKotlinCompilerIntegration
    }

    fun testOldJvmAgainstFir() {
-        val library = compileLibrary("library", additionalOptions = listOf("-Xuse-k2"))
+        val library = compileLibrary("library", additionalOptions = listOf("-language-version", "2.0"))
        compileKotlin("source.kt", tmpdir, listOf(library))

-        val library2 = compileLibrary("library", additionalOptions = listOf("-Xuse-k2", "-Xabi-stability=unstable"))
+        val library2 = compileLibrary("library", additionalOptions = listOf("-language-version", "2.0", "-Xabi-stability=unstable"))
        compileKotlin("source.kt", tmpdir, listOf(library2))
    }

@@ -691,13 +691,13 @@ class CompileKotlinAgainstCustomBinariesTest : AbstractKotlinCompilerIntegration
    }

    fun testOldJvmAgainstFirWithStableAbi() {
-        val library = compileLibrary("library", additionalOptions = listOf("-Xuse-k2", "-Xabi-stability=stable"))
+        val library = compileLibrary("library", additionalOptions = listOf("-language-version", "2.0", "-Xabi-stability=stable"))
        compileKotlin("source.kt", tmpdir, listOf(library))
    }

    fun testOldJvmAgainstFirWithAllowUnstableDependencies() {
-        val library = compileLibrary("library", additionalOptions = listOf("-Xuse-k2"))
-        compileKotlin("source.kt", tmpdir, listOf(library), additionalOptions = listOf("-Xallow-unstable-dependencies"))
+        val library = compileLibrary("library", additionalOptions = listOf("-language-version", "2.0"))
+        compileKotlin("source.kt", tmpdir, listOf(library), additionalOptions = listOf("-Xallow-unstable-dependencies", "-Xskip-metadata-version-check"))
    }

    fun testSealedClassesAndInterfaces() {
@@ -63,6 +63,9 @@ class ApiVersion private constructor(
        @JvmField
        val KOTLIN_1_9 = createByLanguageVersion(LanguageVersion.KOTLIN_1_9)

+        @JvmField
+        val KOTLIN_2_0 = createByLanguageVersion(LanguageVersion.KOTLIN_2_0)
+
        @JvmField
        val LATEST: ApiVersion = createByLanguageVersion(LanguageVersion.values().last())

@@ -282,6 +282,11 @@ enum class LanguageFeature(
    ValueClassesSecondaryConstructorWithBody(sinceVersion = KOTLIN_1_9, kind = UNSTABLE_FEATURE), // KT-55333
    NativeJsProhibitLateinitIsInitalizedIntrinsicWithoutPrivateAccess(KOTLIN_1_9, kind = BUG_FIX), // KT-27002

+    // End of 1.* language features --------------------------------------------------
+
+    // 2.0
+
+    // End of 2.* language features --------------------------------------------------

    // This feature effectively might be removed because we decided to disable it until K2 and there it will be unconditionally enabled.
    // But we leave it here just to minimize the changes in K1 and also to allow use the feature once somebody needs it.
@@ -414,11 +419,16 @@ enum class LanguageVersion(val major: Int, val minor: Int) : DescriptionAware, L
    KOTLIN_1_7(1, 7),
    KOTLIN_1_8(1, 8),
    KOTLIN_1_9(1, 9),
+
+    KOTLIN_2_0(2, 0),
    ;

    override val isStable: Boolean
        get() = this <= LATEST_STABLE

+    val usesK2: Boolean
+        get() = this >= KOTLIN_2_0
+
    override val isDeprecated: Boolean
        get() = FIRST_SUPPORTED <= this && this < FIRST_NON_DEPRECATED

@@ -498,6 +508,8 @@ interface LanguageVersionSettings {
    // Please do not use this to enable/disable specific features/checks. Instead add a new LanguageFeature entry and call supportsFeature
    val languageVersion: LanguageVersion

+    fun copy(languageVersion: LanguageVersion): LanguageVersionSettings = this
+
    companion object {
        const val RESOURCE_NAME_TO_ALLOW_READING_FROM_ENVIRONMENT = "META-INF/allow-configuring-from-environment"
    }
@@ -546,6 +558,9 @@ class LanguageVersionSettingsImpl @JvmOverloads constructor(
                state == LanguageFeature.State.ENABLED && feature.forcesPreReleaseBinariesIfEnabled()
            }

+    override fun copy(languageVersion: LanguageVersion): LanguageVersionSettings =
+        LanguageVersionSettingsImpl(languageVersion, apiVersion, analysisFlags, specificFeatures)
+
    companion object {
        @JvmField
        val DEFAULT = LanguageVersionSettingsImpl(LanguageVersion.LATEST_STABLE, ApiVersion.LATEST_STABLE)
@@ -21,7 +21,11 @@ class JvmMetadataVersion(versionArray: IntArray, val isStrictSemantics: Boolean)
                    isCompatibleTo(INSTANCE)
                } else {
                    // Kotlin 1.N is able to read metadata of versions up to Kotlin 1.{N+1} (unless the version has strict semantics).
-                    major == INSTANCE.major && minor <= INSTANCE.minor + 1
+                    // Kotlin 1.9 is able to read Kotlin 2.0
+                    // Kotlin K.* is able to read Kotlin M.* if K > M
+                    major == INSTANCE.major && minor <= INSTANCE.minor + 1 ||
+                            major == 2 && INSTANCE.major == 1 && minor == 9 ||
+                            major < INSTANCE.major
                }

    companion object {
@@ -146,7 +146,7 @@ class KotlinJpsBuildTestIncremental : KotlinJpsBuildTest() {
        // Try to set Language version to Stable+2 (there is no promises that metadata will be supported)
        val experimentalLevelVersion: LanguageVersion
        try {
-            experimentalLevelVersion = LanguageVersion.values()[LanguageVersion.LATEST_STABLE.ordinal+2]
+            experimentalLevelVersion = LanguageVersion.values()[LanguageVersion.LATEST_STABLE.ordinal + 2]
        } catch (e: ArrayIndexOutOfBoundsException) {
            // there is no Stable+2 version for now, skiping test
            return
@@ -16,6 +16,7 @@ enum class KotlinVersion(val version: String) {
    KOTLIN_1_7("1.7"),
    KOTLIN_1_8("1.8"),
    KOTLIN_1_9("1.9"),
+    KOTLIN_2_0("2.0"),
    ;

    companion object {
@@ -538,6 +538,7 @@ public final class org/jetbrains/kotlin/gradle/dsl/KotlinVersion : java/lang/Enu
 	public static final field KOTLIN_1_7 Lorg/jetbrains/kotlin/gradle/dsl/KotlinVersion;
 	public static final field KOTLIN_1_8 Lorg/jetbrains/kotlin/gradle/dsl/KotlinVersion;
 	public static final field KOTLIN_1_9 Lorg/jetbrains/kotlin/gradle/dsl/KotlinVersion;
+	public static final field KOTLIN_2_0 Lorg/jetbrains/kotlin/gradle/dsl/KotlinVersion;
 	public final fun getVersion ()Ljava/lang/String;
 	public static fun valueOf (Ljava/lang/String;)Lorg/jetbrains/kotlin/gradle/dsl/KotlinVersion;
 	public static fun values ()[Lorg/jetbrains/kotlin/gradle/dsl/KotlinVersion;
@@ -9,7 +9,7 @@ interface KotlinCommonCompilerOptions : org.jetbrains.kotlin.gradle.dsl.KotlinCo

    /**
     * Allow using declarations only from the specified version of bundled libraries
-     * Possible values: "1.3 (deprecated)", "1.4 (deprecated)", "1.5", "1.6", "1.7", "1.8", "1.9 (experimental)"
+     * Possible values: "1.3 (deprecated)", "1.4 (deprecated)", "1.5", "1.6", "1.7", "1.8", "1.9 (experimental)", "2.0 (experimental)"
     * Default value: null
     */
    @get:org.gradle.api.tasks.Optional
@@ -18,7 +18,7 @@ interface KotlinCommonCompilerOptions : org.jetbrains.kotlin.gradle.dsl.KotlinCo

    /**
     * Provide source compatibility with the specified version of Kotlin
-     * Possible values: "1.3 (deprecated)", "1.4 (deprecated)", "1.5", "1.6", "1.7", "1.8", "1.9 (experimental)"
+     * Possible values: "1.3 (deprecated)", "1.4 (deprecated)", "1.5", "1.6", "1.7", "1.8", "1.9 (experimental)", "2.0 (experimental)"
     * Default value: null
     */
    @get:org.gradle.api.tasks.Optional
@@ -14,7 +14,7 @@ interface KotlinCommonOptions : org.jetbrains.kotlin.gradle.dsl.KotlinCommonTool

    /**
     * Allow using declarations only from the specified version of bundled libraries
-     * Possible values: "1.3 (deprecated)", "1.4 (deprecated)", "1.5", "1.6", "1.7", "1.8", "1.9 (experimental)"
+     * Possible values: "1.3 (deprecated)", "1.4 (deprecated)", "1.5", "1.6", "1.7", "1.8", "1.9 (experimental)", "2.0 (experimental)"
     * Default value: null
     */
    var apiVersion: kotlin.String?
@@ -27,7 +27,7 @@ interface KotlinCommonOptions : org.jetbrains.kotlin.gradle.dsl.KotlinCommonTool

    /**
     * Provide source compatibility with the specified version of Kotlin
-     * Possible values: "1.3 (deprecated)", "1.4 (deprecated)", "1.5", "1.6", "1.7", "1.8", "1.9 (experimental)"
+     * Possible values: "1.3 (deprecated)", "1.4 (deprecated)", "1.5", "1.6", "1.7", "1.8", "1.9 (experimental)", "2.0 (experimental)"
     * Default value: null
     */
    var languageVersion: kotlin.String?
@@ -145,7 +145,8 @@ private val apiVersionValues = ApiVersion.run {
        KOTLIN_1_6,
        KOTLIN_1_7,
        KOTLIN_1_8,
-        KOTLIN_1_9
+        KOTLIN_1_9,
+        KOTLIN_2_0
    )
 }

@@ -71,7 +71,7 @@ class Kapt3CommandLineProcessor : CommandLineProcessor {
        if (configuration.getBoolean(CommonConfigurationKeys.USE_FIR)) {
            configuration[CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY]?.report(
                CompilerMessageSeverity.ERROR,
-                "kapt currently doesn't support experimental K2 compiler\nDisable K2 compiler by removing -Xuse-k2 flag"
+                "kapt currently doesn't support language version 2.0\nPlease use language version 1.* (e.g. 1.9) instead"
            )
        }