[K2] Support legacy serialization for custom function type extensions.

For Compose libraries, it is important that libraries built with
K2 in version 2.0 can be read and used by a version 1.9 K1
compiler. That is not possible if custom function types are
in the metadata.

^KT-58456 Fixed

compiler/fir/analysis-tests/test/org/jetbrains/kotlin/test/LoadedMetadataDumpHandler.kt

@@ -9,6 +9,7 @@ import com.intellij.openapi.vfs.StandardFileSystems
 import com.intellij.openapi.vfs.VirtualFileManager
 import org.jetbrains.kotlin.cli.common.prepareJvmSessions
 import org.jetbrains.kotlin.cli.jvm.compiler.VfsBasedProjectEnvironment
+import org.jetbrains.kotlin.config.ApiVersion
 import org.jetbrains.kotlin.config.LanguageVersionSettingsImpl
 import org.jetbrains.kotlin.fir.BinaryModuleData
 import org.jetbrains.kotlin.fir.DependencyListForCliModule
@@ -26,7 +27,9 @@ import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.jvm.platform.JvmPlatformAnalyzerServices
 import org.jetbrains.kotlin.test.backend.handlers.JvmBinaryArtifactHandler
+import org.jetbrains.kotlin.test.directives.LanguageSettingsDirectives.LANGUAGE_VERSION
 import org.jetbrains.kotlin.test.directives.model.RegisteredDirectives
+import org.jetbrains.kotlin.test.directives.model.singleOrZeroValue
 import org.jetbrains.kotlin.test.frontend.classic.ClassicFrontendOutputArtifact
 import org.jetbrains.kotlin.test.frontend.fir.FirOutputArtifact
 import org.jetbrains.kotlin.test.model.*
@@ -42,11 +45,17 @@ class LoadedMetadataDumpHandler(testServices: TestServices) : JvmBinaryArtifactH
 
     override fun processModule(module: TestModule, info: BinaryArtifacts.Jvm) {
         if (testServices.loadedMetadataSuppressionDirective in module.directives) return
+        val languageVersion = module.directives.singleOrZeroValue(LANGUAGE_VERSION)
+        val languageVersionSettings = if (languageVersion != null) {
+            LanguageVersionSettingsImpl(languageVersion, ApiVersion.createByLanguageVersion(languageVersion))
+        } else {
+            LanguageVersionSettingsImpl.DEFAULT
+        }
         val emptyModule = TestModule(
             name = "empty", JvmPlatforms.defaultJvmPlatform, TargetBackend.JVM_IR, FrontendKinds.FIR,
             BackendKinds.IrBackend, ArtifactKinds.Jvm, files = emptyList(),
             allDependencies = listOf(DependencyDescription(module.name, DependencyKind.Binary, DependencyRelation.RegularDependency)),
-            RegisteredDirectives.Empty, LanguageVersionSettingsImpl.DEFAULT
+            RegisteredDirectives.Empty, languageVersionSettings
         )
         val configuration = testServices.compilerConfigurationProvider.getCompilerConfiguration(emptyModule)
         val environment = VfsBasedProjectEnvironment(

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt

@@ -7,7 +7,9 @@ package org.jetbrains.kotlin.fir.serialization
 
 import org.jetbrains.kotlin.builtins.StandardNames
 import org.jetbrains.kotlin.builtins.functions.FunctionTypeKind
+import org.jetbrains.kotlin.builtins.functions.isBuiltin
 import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.config.LanguageVersion
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.constant.EnumValue
 import org.jetbrains.kotlin.constant.IntValue
@@ -823,7 +825,8 @@ class FirElementSerializer private constructor(
                 return lowerBound
             }
             is ConeClassLikeType -> {
-                if (type.functionTypeKind(session) == FunctionTypeKind.SuspendFunction) {
+                val functionTypeKind = type.functionTypeKind(session)
+                if (functionTypeKind == FunctionTypeKind.SuspendFunction) {
                     val runtimeFunctionType = type.suspendFunctionTypeToFunctionTypeWithContinuation(
                         session, StandardClassIds.Continuation
                     )
@@ -831,6 +834,13 @@ class FirElementSerializer private constructor(
                     functionType.flags = Flags.getTypeFlags(true, false)
                     return functionType
                 }
+                if (functionTypeKind?.isBuiltin == false) {
+                    val legacySerializationUntil =
+                        LanguageVersion.fromVersionString(functionTypeKind.serializeAsFunctionWithAnnotationUntil)
+                    if (legacySerializationUntil != null && languageVersionSettings.languageVersion < legacySerializationUntil) {
+                        return typeProto(type.customFunctionTypeToSimpleFunctionType(session))
+                    }
+                }
                 fillFromPossiblyInnerType(builder, type)
                 if (type.hasContextReceivers) {
                     typeAnnotations.addIfNotNull(

core/compiler.common/src/org/jetbrains/kotlin/builtins/functions/FunctionTypeKind.kt

@@ -63,6 +63,22 @@ abstract class FunctionTypeKind internal constructor(
     open val prefixForTypeRender: String?
         get() = null
 
+
+    /**
+     * Specifies the first language version for which to serialize custom function types
+     * into kotlin metadata. Until that version, custom function types will be serialized
+     * with the legacy scheme: as a FunctionN/KFunctionN with the annotation used for the
+     * custom function type.
+     *
+     * If no version is specified, custom function types are serialized to kotlin metadata.
+     *
+     * Serialization using the legacy format allows libraries compiled with K2 with a
+     * K2 plugin that uses custom function types to be used by clients using a K1 compiler
+     * with a K1 compiler plugin that understands the custom function types.
+     */
+    open val serializeAsFunctionWithAnnotationUntil: String?
+        get() = null
+
     /**
      * @return corresponding non-reflect kind for reflect kind
      * @return [this] if [isReflectType] is false

generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt

@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.assignment.plugin.AbstractFirLightTreeBlackBoxCodege
 import org.jetbrains.kotlin.assignment.plugin.AbstractFirPsiAssignmentPluginDiagnosticTest
 import org.jetbrains.kotlin.assignment.plugin.AbstractIrBlackBoxCodegenTestAssignmentPlugin
 import org.jetbrains.kotlin.fir.plugin.runners.AbstractFirLightTreePluginBlackBoxCodegenTest
+import org.jetbrains.kotlin.fir.plugin.runners.AbstractFirLoadK2CompiledKotlinWithPluginTest
 import org.jetbrains.kotlin.fir.plugin.runners.AbstractFirPsiPluginDiagnosticTest
 import org.jetbrains.kotlin.generators.generateTestGroupSuiteWithJUnit5
 import org.jetbrains.kotlin.generators.impl.generateTestGroupSuite
@@ -262,6 +263,10 @@ fun main(args: Array<String>) {
             testClass<AbstractFirLightTreePluginBlackBoxCodegenTest> {
                 model("box")
             }
+
+            testClass<AbstractFirLoadK2CompiledKotlinWithPluginTest> {
+                model("firLoadK2Compiled")
+            }
         }
 
         testGroup(

plugins/fir-plugin-prototype/build.gradle.kts

@@ -22,6 +22,7 @@ dependencies {
     testApi(projectTests(":compiler:tests-common-new"))
     testApi(projectTests(":compiler:test-infrastructure"))
     testApi(projectTests(":compiler:test-infrastructure-utils"))
+    testApi(projectTests(":compiler:fir:analysis-tests"))
     testApi(project(":compiler:fir:checkers"))
     testApi(project(":compiler:fir:checkers:checkers.jvm"))
     testApi(project(":compiler:fir:checkers:checkers.js"))

plugins/fir-plugin-prototype/src/org/jetbrains/kotlin/fir/plugin/types/ComposableLikeFunctionTypeKindExtension.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.plugin.types
 
 import org.jetbrains.kotlin.builtins.functions.FunctionTypeKind
+import org.jetbrains.kotlin.config.LanguageVersion
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.extensions.FirFunctionTypeKindExtension
 import org.jetbrains.kotlin.fir.plugin.fqn
@@ -31,6 +32,9 @@ object ComposableFunction : FunctionTypeKind(
     override val prefixForTypeRender: String
         get() = "@MyComposable"
 
+    override val serializeAsFunctionWithAnnotationUntil: String
+        get() = LanguageVersion.KOTLIN_2_1.versionString
+
     override fun reflectKind(): FunctionTypeKind = KComposableFunction
 }
 
@@ -40,5 +44,8 @@ object KComposableFunction : FunctionTypeKind(
     MY_COMPOSABLE_ANNOTATION_CLASS_ID,
     isReflectType = true
 ) {
+    override val serializeAsFunctionWithAnnotationUntil: String
+        get() = LanguageVersion.KOTLIN_2_1.versionString
+
     override fun nonReflectKind(): FunctionTypeKind = ComposableFunction
 }

plugins/fir-plugin-prototype/testData/firLoadK2Compiled/simple-lang-ver-2.1.fir.k2.txt

@@ -0,0 +1 @@
+public final fun runComposable(block: R|@R|org/jetbrains/kotlin/fir/plugin/MyComposable|()  some/MyComposableFunction0<kotlin/Unit>|): R|kotlin/Unit|

plugins/fir-plugin-prototype/testData/firLoadK2Compiled/simple-lang-ver-2.1.kt

@@ -0,0 +1,7 @@
+// API_VERSION: 2.0
+// LANGUAGE_VERSION: 2.1
+package test
+
+import org.jetbrains.kotlin.fir.plugin.MyComposable
+
+fun runComposable(block: @MyComposable () -> Unit) {}

plugins/fir-plugin-prototype/testData/firLoadK2Compiled/simple.fir.k2.txt

@@ -0,0 +1 @@
+public final fun runComposable(block: R|@R|org/jetbrains/kotlin/fir/plugin/MyComposable|()  () -> kotlin/Unit|): R|kotlin/Unit|

plugins/fir-plugin-prototype/testData/firLoadK2Compiled/simple.kt

@@ -0,0 +1,8 @@
+// API_VERSION: 2.0
+// LANGUAGE_VERSION: 2.0
+package test
+
+import org.jetbrains.kotlin.fir.plugin.MyComposable
+
+fun runComposable(block: @MyComposable () -> Unit) {}
+

plugins/fir-plugin-prototype/tests-gen/org/jetbrains/kotlin/fir/plugin/runners/FirLoadK2CompiledKotlinWithPluginTestGenerated.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.plugin.runners;
+
+import com.intellij.testFramework.TestDataPath;
+import org.jetbrains.kotlin.test.util.KtTestUtil;
+import org.jetbrains.kotlin.test.TargetBackend;
+import org.jetbrains.kotlin.test.TestMetadata;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.util.regex.Pattern;
+
+/** This class is generated by {@link org.jetbrains.kotlin.generators.tests.GenerateTestsKt}. DO NOT MODIFY MANUALLY */
+@SuppressWarnings("all")
+@TestMetadata("plugins/fir-plugin-prototype/testData/firLoadK2Compiled")
+@TestDataPath("$PROJECT_ROOT")
+public class FirLoadK2CompiledKotlinWithPluginTestGenerated extends AbstractFirLoadK2CompiledKotlinWithPluginTest {
+    @Test
+    public void testAllFilesPresentInFirLoadK2Compiled() throws Exception {
+        KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("plugins/fir-plugin-prototype/testData/firLoadK2Compiled"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM_IR, true);
+    }
+
+    @Test
+    @TestMetadata("simple.kt")
+    public void testSimple() throws Exception {
+        runTest("plugins/fir-plugin-prototype/testData/firLoadK2Compiled/simple.kt");
+    }
+
+    @Test
+    @TestMetadata("simple-lang-ver-2.1.kt")
+    public void testSimple_lang_ver_2_1() throws Exception {
+        runTest("plugins/fir-plugin-prototype/testData/firLoadK2Compiled/simple-lang-ver-2.1.kt");
+    }
+}

plugins/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/runners/PluginPrototypeTests.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.fir.plugin.services.PluginAnnotationsProvider
 import org.jetbrains.kotlin.test.builders.TestConfigurationBuilder
 import org.jetbrains.kotlin.test.directives.FirDiagnosticsDirectives.ENABLE_PLUGIN_PHASES
 import org.jetbrains.kotlin.test.directives.FirDiagnosticsDirectives.FIR_DUMP
+import org.jetbrains.kotlin.test.runners.AbstractFirLoadK2CompiledKotlin
 import org.jetbrains.kotlin.test.runners.AbstractFirPsiDiagnosticTest
 import org.jetbrains.kotlin.test.runners.codegen.AbstractFirLightTreeBlackBoxCodegenTest
 import org.jetbrains.kotlin.test.runners.enableLazyResolvePhaseChecking
@@ -28,6 +29,13 @@ abstract class AbstractFirPsiPluginDiagnosticTest : AbstractFirPsiDiagnosticTest
     }
 }
 
+open class AbstractFirLoadK2CompiledKotlinWithPluginTest : AbstractFirLoadK2CompiledKotlin() {
+    override fun configure(builder: TestConfigurationBuilder) {
+        super.configure(builder)
+        builder.commonFirWithPluginFrontendConfiguration()
+    }
+}
+
 fun TestConfigurationBuilder.commonFirWithPluginFrontendConfiguration() {
     enableLazyResolvePhaseChecking()