[cls] write flexible type information to cls

^KTIJ-25172
this information would be used to create resolved FirElements from stubs,
so no ProtoBuf would be kept in memory

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/AnnotatedFlexibleTypes/AnnotatedFlexibleTypes.kt

@@ -0,0 +1,9 @@
+package test
+
+public class AnnotatedFlexibleTypes(val javaClass: d.JavaClass) {
+    fun foo() = javaClass.foo()
+
+    val bar = javaClass.bar()
+
+    val baz = javaClass.baz()
+}

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/AnnotatedFlexibleTypes/AnnotatedFlexibleTypes.txt

@@ -0,0 +1,72 @@
+PsiJetFileStubImpl[package=test]
+KotlinStub$PACKAGE_DIRECTIVE
+  KotlinStub$REFERENCE_EXPRESSION[referencedName=test]
+KotlinStub$IMPORT_LIST
+KotlinStub$CLASS[classId=test/AnnotatedFlexibleTypes, fqName=test.AnnotatedFlexibleTypes, isEnumEntry=false, isInterface=false, isLocal=false, isTopLevel=true, name=AnnotatedFlexibleTypes, superNames=[]]
+  KotlinStub$MODIFIER_LIST[public final]
+  KotlinStub$PRIMARY_CONSTRUCTOR[fqName=null, hasBody=false, isDelegatedCallToThis=false, isExtension=false, isTopLevel=false, name=AnnotatedFlexibleTypes]
+    KotlinStub$MODIFIER_LIST[public]
+    KotlinStub$VALUE_PARAMETER_LIST
+      KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=javaClass]
+        KotlinStub$TYPE_REFERENCE
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=d]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=JavaClass]
+  KotlinStub$CLASS_BODY
+    KotlinStub$PROPERTY[fqName=test.AnnotatedFlexibleTypes.bar, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=bar]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE    ft: kotlin.collections.Collection<kotlin.Int .. kotlin.Int?>?
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=collections]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=MutableCollection]
+          KotlinStub$TYPE_ARGUMENT_LIST
+            KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+              KotlinStub$TYPE_REFERENCE
+                KotlinStub$USER_TYPE    ft: kotlin.Int?
+                  KotlinStub$USER_TYPE
+                    KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+                  KotlinStub$REFERENCE_EXPRESSION[referencedName=Int]
+    KotlinStub$PROPERTY[fqName=test.AnnotatedFlexibleTypes.baz, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=baz]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE    ft: kotlin.collections.Collection<kotlin.collections.MutableCollection<kotlin.Int .. kotlin.Int?> .. kotlin.collections.Collection<kotlin.Int .. kotlin.Int?>?>?
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=collections]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=MutableCollection]
+          KotlinStub$TYPE_ARGUMENT_LIST
+            KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+              KotlinStub$TYPE_REFERENCE
+                KotlinStub$USER_TYPE    ft: kotlin.collections.Collection<kotlin.Int .. kotlin.Int?>?
+                  KotlinStub$USER_TYPE
+                    KotlinStub$USER_TYPE
+                      KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+                    KotlinStub$REFERENCE_EXPRESSION[referencedName=collections]
+                  KotlinStub$REFERENCE_EXPRESSION[referencedName=MutableCollection]
+                  KotlinStub$TYPE_ARGUMENT_LIST
+                    KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+                      KotlinStub$TYPE_REFERENCE
+                        KotlinStub$USER_TYPE    ft: kotlin.Int?
+                          KotlinStub$USER_TYPE
+                            KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+                          KotlinStub$REFERENCE_EXPRESSION[referencedName=Int]
+    KotlinStub$PROPERTY[fqName=test.AnnotatedFlexibleTypes.javaClass, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=javaClass]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=d]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=JavaClass]
+    KotlinStub$FUN[fqName=test.AnnotatedFlexibleTypes.foo, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=false, mayHaveContract=false, name=foo]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$VALUE_PARAMETER_LIST
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE    ft: kotlin.Int?
+          KotlinStub$USER_TYPE
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=Int]

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/AnnotatedFlexibleTypes/d/JavaClass.java

@@ -0,0 +1,15 @@
+package d;
+
+import org.jetbrains.annotations.*;
+import kotlin.annotations.jvm.*;
+
+public abstract class JavaClass {
+    @Nullable
+    public abstract Integer foo();
+
+    @Mutable
+    public abstract java.util.Collection<Integer> bar();
+
+    @Mutable
+    public abstract java.util.Collection<java.util.Collection<Integer>> baz();
+}

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/OuterClassesWithFlexibleArgs/OuterClassesWithFlexibleArgs.kt

@@ -0,0 +1,5 @@
+package test
+
+public class OuterClassesWithFlexibleArgs<K, L>(k: K, l: L) {
+    val baz = d.JavaClass.baz(k, l)
+}

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/OuterClassesWithFlexibleArgs/OuterClassesWithFlexibleArgs.txt

@@ -0,0 +1,40 @@
+PsiJetFileStubImpl[package=test]
+KotlinStub$PACKAGE_DIRECTIVE
+  KotlinStub$REFERENCE_EXPRESSION[referencedName=test]
+KotlinStub$IMPORT_LIST
+KotlinStub$CLASS[classId=test/OuterClassesWithFlexibleArgs, fqName=test.OuterClassesWithFlexibleArgs, isEnumEntry=false, isInterface=false, isLocal=false, isTopLevel=true, name=OuterClassesWithFlexibleArgs, superNames=[]]
+  KotlinStub$MODIFIER_LIST[public final]
+  KotlinStub$TYPE_PARAMETER_LIST
+    KotlinStub$TYPE_PARAMETER[fqName=null, isInVariance=false, isOutVariance=false, name=K]
+    KotlinStub$TYPE_PARAMETER[fqName=null, isInVariance=false, isOutVariance=false, name=L]
+  KotlinStub$PRIMARY_CONSTRUCTOR[fqName=null, hasBody=false, isDelegatedCallToThis=false, isExtension=false, isTopLevel=false, name=OuterClassesWithFlexibleArgs]
+    KotlinStub$MODIFIER_LIST[public]
+    KotlinStub$VALUE_PARAMETER_LIST
+      KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=k]
+        KotlinStub$TYPE_REFERENCE
+          KotlinStub$USER_TYPE
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=K]
+      KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=l]
+        KotlinStub$TYPE_REFERENCE
+          KotlinStub$USER_TYPE
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=L]
+  KotlinStub$CLASS_BODY
+    KotlinStub$PROPERTY[fqName=test.OuterClassesWithFlexibleArgs.baz, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=baz]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE    ft: d.JavaClass.InnerClass<L .. L?>?
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=d]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=JavaClass]
+            KotlinStub$TYPE_ARGUMENT_LIST
+              KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+                KotlinStub$TYPE_REFERENCE
+                  KotlinStub$USER_TYPE    ft: K?
+                    KotlinStub$REFERENCE_EXPRESSION[referencedName=K]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=InnerClass]
+          KotlinStub$TYPE_ARGUMENT_LIST
+            KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+              KotlinStub$TYPE_REFERENCE
+                KotlinStub$USER_TYPE    ft: L?
+                  KotlinStub$REFERENCE_EXPRESSION[referencedName=L]

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/OuterClassesWithFlexibleArgs/d/JavaClass.java

@@ -0,0 +1,13 @@
+package d;
+
+import org.jetbrains.annotations.*;
+import kotlin.annotations.jvm.*;
+
+public abstract class JavaClass<T> {
+    public class InnerClass<M> {}
+
+    @Mutable
+    public static <K, L> JavaClass<K>.InnerClass<L> baz(K k, L l) {
+        return null;
+    }
+}

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/TypeParametersInFlexibleTypes/TypeParametersInFlexibleTypes.kt

@@ -0,0 +1,9 @@
+package test
+
+public class TypeParametersInFlexibleTypes<A, D>(val javaClass: d.JavaClass<A>, val t: D & Any) {
+    fun foo() = javaClass.foo()
+
+    val bar = javaClass.bar()
+
+    val baz = d.JavaClass.baz(t)
+}

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/TypeParametersInFlexibleTypes/TypeParametersInFlexibleTypes.txt

@@ -0,0 +1,94 @@
+PsiJetFileStubImpl[package=test]
+KotlinStub$PACKAGE_DIRECTIVE
+  KotlinStub$REFERENCE_EXPRESSION[referencedName=test]
+KotlinStub$IMPORT_LIST
+KotlinStub$CLASS[classId=test/TypeParametersInFlexibleTypes, fqName=test.TypeParametersInFlexibleTypes, isEnumEntry=false, isInterface=false, isLocal=false, isTopLevel=true, name=TypeParametersInFlexibleTypes, superNames=[]]
+  KotlinStub$MODIFIER_LIST[public final]
+  KotlinStub$TYPE_PARAMETER_LIST
+    KotlinStub$TYPE_PARAMETER[fqName=null, isInVariance=false, isOutVariance=false, name=A]
+    KotlinStub$TYPE_PARAMETER[fqName=null, isInVariance=false, isOutVariance=false, name=D]
+  KotlinStub$PRIMARY_CONSTRUCTOR[fqName=null, hasBody=false, isDelegatedCallToThis=false, isExtension=false, isTopLevel=false, name=TypeParametersInFlexibleTypes]
+    KotlinStub$MODIFIER_LIST[public]
+    KotlinStub$VALUE_PARAMETER_LIST
+      KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=javaClass]
+        KotlinStub$TYPE_REFERENCE
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=d]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=JavaClass]
+            KotlinStub$TYPE_ARGUMENT_LIST
+              KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+                KotlinStub$TYPE_REFERENCE
+                  KotlinStub$USER_TYPE
+                    KotlinStub$REFERENCE_EXPRESSION[referencedName=A]
+      KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=t]
+        KotlinStub$TYPE_REFERENCE
+          KotlinStub$INTERSECTION_TYPE
+            KotlinStub$TYPE_REFERENCE
+              KotlinStub$USER_TYPE
+                KotlinStub$REFERENCE_EXPRESSION[referencedName=D]
+            KotlinStub$TYPE_REFERENCE
+              KotlinStub$USER_TYPE
+                KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+  KotlinStub$CLASS_BODY
+    KotlinStub$PROPERTY[fqName=test.TypeParametersInFlexibleTypes.bar, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=bar]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE    ft: kotlin.collections.Collection<A .. A?>?
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=collections]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=MutableCollection]
+          KotlinStub$TYPE_ARGUMENT_LIST
+            KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+              KotlinStub$TYPE_REFERENCE
+                KotlinStub$USER_TYPE    ft: A?
+                  KotlinStub$REFERENCE_EXPRESSION[referencedName=A]
+    KotlinStub$PROPERTY[fqName=test.TypeParametersInFlexibleTypes.baz, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=baz]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE    ft: kotlin.collections.Collection<D & Any .. D?>?
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=collections]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=MutableCollection]
+          KotlinStub$TYPE_ARGUMENT_LIST
+            KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+              KotlinStub$TYPE_REFERENCE
+                KotlinStub$INTERSECTION_TYPE
+                  KotlinStub$TYPE_REFERENCE
+                    KotlinStub$USER_TYPE    ft: D?
+                      KotlinStub$REFERENCE_EXPRESSION[referencedName=D]
+                  KotlinStub$TYPE_REFERENCE
+                    KotlinStub$USER_TYPE
+                      KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+    KotlinStub$PROPERTY[fqName=test.TypeParametersInFlexibleTypes.javaClass, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=javaClass]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=d]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=JavaClass]
+          KotlinStub$TYPE_ARGUMENT_LIST
+            KotlinStub$TYPE_PROJECTION[projectionKind=NONE]
+              KotlinStub$TYPE_REFERENCE
+                KotlinStub$USER_TYPE
+                  KotlinStub$REFERENCE_EXPRESSION[referencedName=A]
+    KotlinStub$PROPERTY[fqName=test.TypeParametersInFlexibleTypes.t, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=t]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$INTERSECTION_TYPE
+          KotlinStub$TYPE_REFERENCE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=D]
+          KotlinStub$TYPE_REFERENCE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+    KotlinStub$FUN[fqName=test.TypeParametersInFlexibleTypes.foo, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=false, mayHaveContract=false, name=foo]
+      KotlinStub$MODIFIER_LIST[public final]
+      KotlinStub$VALUE_PARAMETER_LIST
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE    ft: A?
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=A]

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/TypeParametersInFlexibleTypes/d/JavaClass.java

@@ -0,0 +1,17 @@
+package d;
+
+import org.jetbrains.annotations.*;
+import kotlin.annotations.jvm.*;
+
+public abstract class JavaClass<T> {
+    @Nullable
+    public abstract T foo();
+
+    @Mutable
+    public abstract java.util.Collection<T> bar();
+
+    @Mutable
+    public static <K> java.util.Collection<K> baz(K t) {
+        return new java.util.ArrayList<>();
+    }
+}

analysis/decompiled/decompiler-to-file-stubs/tests/org/jetbrains/kotlin/analysis/decompiler/stub/files/AbstractAdditionalStubInfoTest.kt

@@ -0,0 +1,80 @@
+/*
+ * 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.analysis.decompiler.stub.files
+
+import com.intellij.psi.stubs.StubElement
+import com.intellij.util.indexing.FileContentImpl
+import org.jetbrains.kotlin.analysis.decompiler.stub.file.KotlinClsStubBuilder
+import org.jetbrains.kotlin.psi.KtProjectionKind
+import org.jetbrains.kotlin.psi.stubs.impl.*
+import org.jetbrains.kotlin.test.KotlinTestUtils
+import java.nio.file.Paths
+
+abstract class AbstractAdditionalStubInfoTest : AbstractDecompiledClassTest() {
+    fun runTest(testDirectory: String) {
+        val testDirectoryPath = Paths.get(testDirectory)
+        val testData = TestData.createFromDirectory(testDirectoryPath)
+        val stub = KotlinClsStubBuilder().buildFileStub(FileContentImpl.createByFile(getClassFileToDecompile(testData, false)))!!
+        val builder = StringBuilder()
+        extractAdditionInfo(stub, builder, 0)
+        KotlinTestUtils.assertEqualsToFile(testData.expectedFile, builder.toString())
+    }
+
+    private fun extractAdditionInfo(stub: StubElement<*>, builder: StringBuilder, level: Int) {
+        builder.append(stub.toString())
+        if (stub is KotlinUserTypeStubImpl) {
+            val upperBound = stub.upperBound
+            if (upperBound != null) {
+                builder.append("    ft: ")
+                appendFlexibleTypeInfo(builder, upperBound)
+            }
+        }
+        for (child in stub.childrenStubs) {
+            builder.append("\n").append("  ".repeat(level))
+            extractAdditionInfo(child, builder, level + 1)
+        }
+    }
+
+    private fun appendFlexibleTypeInfo(builder: StringBuilder, typeBean: KotlinTypeBean) {
+        when (typeBean) {
+            is KotlinClassTypeBean -> {
+                builder.append(typeBean.classId.asFqNameString())
+                val arguments = typeBean.arguments
+                if (arguments.isNotEmpty()) {
+                    builder.append("<")
+                    arguments.forEachIndexed { index, arg ->
+                        if (index > 0) builder.append(", ")
+                        if (arg.projectionKind != KtProjectionKind.NONE) {
+                            builder.append(arg.projectionKind.name)
+                        }
+                        if (arg.projectionKind != KtProjectionKind.STAR) {
+                            appendFlexibleTypeInfo(builder, arg.type!!)
+                        }
+                    }
+                    builder.append(">")
+                }
+                if (typeBean.nullable) {
+                    builder.append("?")
+                }
+            }
+            is KotlinTypeParameterTypeBean -> {
+                builder.append(typeBean.typeParameterName)
+                if (typeBean.nullable) {
+                    builder.append("?")
+                }
+                if (typeBean.definitelyNotNull) {
+                    builder.append(" & Any")
+                }
+            }
+
+            is KotlinFlexibleTypeBean -> {
+                appendFlexibleTypeInfo(builder, typeBean.lowerBound)
+                builder.append(" .. ")
+                appendFlexibleTypeInfo(builder, typeBean.upperBound)
+            }
+        }
+    }
+}

analysis/decompiled/decompiler-to-file-stubs/tests/org/jetbrains/kotlin/analysis/decompiler/stub/files/AbstractDecompiledClassTest.kt

@@ -0,0 +1,123 @@
+/*
+ * 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.analysis.decompiler.stub.files
+
+import com.intellij.core.CoreApplicationEnvironment
+import com.intellij.openapi.vfs.VfsUtilCore
+import com.intellij.openapi.vfs.VirtualFile
+import com.intellij.openapi.vfs.impl.jar.CoreJarFileSystem
+import org.jetbrains.kotlin.analysis.decompiler.stub.file.CachedAttributeData
+import org.jetbrains.kotlin.analysis.decompiler.stub.file.ClsKotlinBinaryClassCache
+import org.jetbrains.kotlin.analysis.decompiler.stub.file.FileAttributeService
+import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment
+import org.jetbrains.kotlin.test.*
+import org.jetbrains.kotlin.utils.addIfNotNull
+import java.io.DataInput
+import java.io.DataOutput
+import java.nio.file.Files
+import java.nio.file.Path
+import java.util.stream.Collectors
+import kotlin.io.path.absolutePathString
+import kotlin.io.path.name
+import kotlin.io.path.readText
+
+abstract class AbstractDecompiledClassTest : KotlinTestWithEnvironment() {
+    override fun createEnvironment(): KotlinCoreEnvironment {
+        return KotlinTestUtils.createEnvironmentWithMockJdkAndIdeaAnnotations(
+            ApplicationEnvironmentDisposer.ROOT_DISPOSABLE,
+            ConfigurationKind.JDK_NO_RUNTIME
+        )
+    }
+
+    override fun setUp() {
+        super.setUp()
+
+        with(environment.projectEnvironment.environment) {
+            registerApplicationServices()
+        }
+    }
+
+    private fun CoreApplicationEnvironment.registerApplicationServices() {
+        if (application.getService(FileAttributeService::class.java) == null) {
+            registerApplicationService(FileAttributeService::class.java, DummyFileAttributeService)
+            registerApplicationService(ClsKotlinBinaryClassCache::class.java, ClsKotlinBinaryClassCache())
+        }
+    }
+
+    internal fun getClassFileToDecompile(testData: TestData, useStringTable: Boolean): VirtualFile {
+        val extraOptions = buildList {
+            this.add("-Xallow-kotlin-package")
+            if (useStringTable) {
+                this.add("-Xuse-type-table")
+            }
+            this.addAll(testData.additionalCompilerOptions)
+        }
+        val library = CompilerTestUtil.compileJvmLibrary(
+            src = testData.directory.toFile(),
+            extraOptions = extraOptions,
+        ).toPath()
+        return findClassFileByName(
+            library, testData.jvmFileName
+        )
+    }
+
+    private fun findClassFileByName(library: Path, className: String): VirtualFile {
+        val jarFileSystem = environment.projectEnvironment.environment.jarFileSystem as CoreJarFileSystem
+        val root = jarFileSystem.refreshAndFindFileByPath(library.absolutePathString() + "!/")!!
+        val files = mutableSetOf<VirtualFile>()
+        VfsUtilCore.iterateChildrenRecursively(
+            root,
+            /*filter=*/{ virtualFile ->
+                virtualFile.isDirectory || virtualFile.name == "$className.class"
+            },
+            /*iterator=*/{ virtualFile ->
+                if (!virtualFile.isDirectory) {
+                    files.addIfNotNull(virtualFile)
+                }
+                true
+            })
+
+        return files.single()
+    }
+
+}
+
+internal data class TestData(
+    val directory: Path,
+    val mainKotlinFile: Path,
+    val expectedFile: Path,
+    val jvmFileName: String,
+    val additionalCompilerOptions: List<String>,
+) {
+    companion object {
+        fun createFromDirectory(directory: Path): TestData {
+            val allFiles = Files.list(directory).collect(Collectors.toList())
+            val mainKotlinFile = allFiles.single { path: Path ->
+                path.name.replaceFirstChar { Character.toUpperCase(it) } == "${directory.name.removeSuffix("Kt")}.kt"
+            }
+            val fileText = mainKotlinFile.readText()
+            val jvmFileName = InTextDirectivesUtils.findStringWithPrefixes(fileText, "JVM_FILE_NAME:") ?: directory.name
+            val additionalCompilerOptions = InTextDirectivesUtils.findListWithPrefixes(fileText, "// !LANGUAGE: ").map { "-XXLanguage:$it" }
+            return TestData(
+                directory = directory,
+                mainKotlinFile = mainKotlinFile,
+                expectedFile = allFiles.single { it.fileName.toString() == "${directory.name}.txt" },
+                jvmFileName = jvmFileName,
+                additionalCompilerOptions = additionalCompilerOptions,
+            )
+        }
+    }
+}
+
+object DummyFileAttributeService : FileAttributeService {
+    override fun <T> write(file: VirtualFile, id: String, value: T, writeValueFun: (DataOutput, T) -> Unit): CachedAttributeData<T> {
+        return CachedAttributeData(value, 0)
+    }
+
+    override fun <T> read(file: VirtualFile, id: String, readValueFun: (DataInput) -> T): CachedAttributeData<T>? {
+        return null
+    }
+}

analysis/decompiled/decompiler-to-file-stubs/tests/org/jetbrains/kotlin/analysis/decompiler/stub/files/AbstractStubBuilderTest.kt

@@ -5,55 +5,17 @@
 
 package org.jetbrains.kotlin.analysis.decompiler.stub.files
 
-import com.intellij.core.CoreApplicationEnvironment
-import com.intellij.openapi.vfs.VfsUtilCore
 import com.intellij.openapi.vfs.VirtualFile
-import com.intellij.openapi.vfs.impl.jar.CoreJarFileSystem
 import com.intellij.psi.PsiElement
 import com.intellij.psi.impl.DebugUtil
 import com.intellij.psi.stubs.PsiFileStub
 import com.intellij.psi.stubs.StubElement
-import org.jetbrains.kotlin.analysis.decompiler.stub.file.CachedAttributeData
-import org.jetbrains.kotlin.analysis.decompiler.stub.file.ClsKotlinBinaryClassCache
-import org.jetbrains.kotlin.analysis.decompiler.stub.file.FileAttributeService
-import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment
 import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.psi.stubs.impl.STUB_TO_STRING_PREFIX
-import org.jetbrains.kotlin.test.*
+import org.jetbrains.kotlin.test.KotlinTestUtils
-import org.jetbrains.kotlin.utils.addIfNotNull
-import java.io.DataInput
-import java.io.DataOutput
-import java.nio.file.Files
-import java.nio.file.Path
 import java.nio.file.Paths
-import java.util.stream.Collectors
-import kotlin.io.path.absolutePathString
-import kotlin.io.path.name
-import kotlin.io.path.readText
-
-abstract class AbstractStubBuilderTest : KotlinTestWithEnvironment() {
-    override fun createEnvironment(): KotlinCoreEnvironment {
-        return KotlinTestUtils.createEnvironmentWithMockJdkAndIdeaAnnotations(
-            ApplicationEnvironmentDisposer.ROOT_DISPOSABLE,
-            ConfigurationKind.JDK_NO_RUNTIME
-        )
-    }
-
-    override fun setUp() {
-        super.setUp()
-
-        with(environment.projectEnvironment.environment) {
-            registerApplicationServices()
-        }
-    }
-
-    private fun CoreApplicationEnvironment.registerApplicationServices() {
-        if (application.getService(FileAttributeService::class.java) == null) {
-            registerApplicationService(FileAttributeService::class.java, DummyFileAttributeService)
-            registerApplicationService(ClsKotlinBinaryClassCache::class.java, ClsKotlinBinaryClassCache())
-        }
-    }
 
+abstract class AbstractStubBuilderTest : AbstractDecompiledClassTest() {
     fun runTest(testDirectory: String) {
         val testDirectoryPath = Paths.get(testDirectory)
         val testData = TestData.createFromDirectory(testDirectoryPath)
@@ -73,43 +35,6 @@ abstract class AbstractStubBuilderTest : KotlinTestWithEnvironment() {
     }
 
     protected abstract fun getStubToTest(classFile: VirtualFile): PsiFileStub<*>
-
-    private fun getClassFileToDecompile(testData: TestData, useStringTable: Boolean): VirtualFile {
-        val extraOptions = buildList {
-            add("-Xallow-kotlin-package")
-            if (useStringTable) {
-                add("-Xuse-type-table")
-            }
-            addAll(testData.additionalCompilerOptions)
-        }
-
-        val library = CompilerTestUtil.compileJvmLibrary(
-            src = testData.directory.toFile(),
-            extraOptions = extraOptions,
-        ).toPath()
-
-        return findClassFileByName(library, testData.jvmFileName)
-    }
-
-    private fun findClassFileByName(library: Path, className: String): VirtualFile {
-        val jarFileSystem = environment.projectEnvironment.environment.jarFileSystem as CoreJarFileSystem
-        val root = jarFileSystem.refreshAndFindFileByPath(library.absolutePathString() + "!/")!!
-        val files = mutableSetOf<VirtualFile>()
-        VfsUtilCore.iterateChildrenRecursively(
-            root,
-            /*filter=*/{ virtualFile ->
-                virtualFile.isDirectory || virtualFile.name == "$className.class"
-            },
-            /*iterator=*/{ virtualFile ->
-                if (!virtualFile.isDirectory) {
-                    files.addIfNotNull(virtualFile)
-                }
-                true
-            })
-
-        return files.single()
-    }
-
 }
 
 private fun StubElement<out PsiElement>.serializeToString(): String {
@@ -130,40 +55,3 @@ private fun serializeStubToString(stubElement: StubElement<*>): String {
     }.replace(", [", "[")
 }
 
-
-private data class TestData(
-    val directory: Path,
-    val mainKotlinFile: Path,
-    val expectedFile: Path,
-    val jvmFileName: String,
-    val additionalCompilerOptions: List<String>,
-) {
-    companion object {
-        fun createFromDirectory(directory: Path): TestData {
-            val allFiles = Files.list(directory).collect(Collectors.toList())
-            val mainKotlinFile = allFiles.single { path: Path ->
-                path.name.replaceFirstChar { Character.toUpperCase(it) } == "${directory.name.removeSuffix("Kt")}.kt"
-            }
-            val fileText = mainKotlinFile.readText()
-            val jvmFileName = InTextDirectivesUtils.findStringWithPrefixes(fileText, "JVM_FILE_NAME:") ?: directory.name
-            val additionalCompilerOptions = InTextDirectivesUtils.findListWithPrefixes(fileText, "// !LANGUAGE: ").map { "-XXLanguage:$it" }
-            return TestData(
-                directory = directory,
-                mainKotlinFile = mainKotlinFile,
-                expectedFile = allFiles.single { it.fileName.toString() == "${directory.name}.txt" },
-                jvmFileName = jvmFileName,
-                additionalCompilerOptions = additionalCompilerOptions,
-            )
-        }
-    }
-}
-
-object DummyFileAttributeService : FileAttributeService {
-    override fun <T> write(file: VirtualFile, id: String, value: T, writeValueFun: (DataOutput, T) -> Unit): CachedAttributeData<T> {
-        return CachedAttributeData(value, 0)
-    }
-
-    override fun <T> read(file: VirtualFile, id: String, readValueFun: (DataInput) -> T): CachedAttributeData<T>? {
-        return null
-    }
-}

analysis/decompiled/decompiler-to-file-stubs/tests/org/jetbrains/kotlin/analysis/decompiler/stub/files/AdditionalStubInfoTestGenerated.java

@@ -0,0 +1,44 @@
+/*
+ * 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.analysis.decompiler.stub.files;
+
+import com.intellij.testFramework.TestDataPath;
+import org.jetbrains.kotlin.test.util.KtTestUtil;
+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.analysis.api.GenerateAnalysisApiTestsKt}. DO NOT MODIFY MANUALLY */
+@SuppressWarnings("all")
+@TestMetadata("analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo")
+@TestDataPath("$PROJECT_ROOT")
+public class AdditionalStubInfoTestGenerated extends AbstractAdditionalStubInfoTest {
+    @Test
+    public void testAllFilesPresentInAdditionalClsStubInfo() throws Exception {
+        KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo"), Pattern.compile("^([^\\.]+)$"), null, false);
+    }
+
+    @Test
+    @TestMetadata("AnnotatedFlexibleTypes")
+    public void testAnnotatedFlexibleTypes() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/AnnotatedFlexibleTypes/");
+    }
+
+    @Test
+    @TestMetadata("OuterClassesWithFlexibleArgs")
+    public void testOuterClassesWithFlexibleArgs() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/OuterClassesWithFlexibleArgs/");
+    }
+
+    @Test
+    @TestMetadata("TypeParametersInFlexibleTypes")
+    public void testTypeParametersInFlexibleTypes() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/TypeParametersInFlexibleTypes/");
+    }
+}

analysis/decompiled/decompiler-to-stubs/src/org/jetbrains/kotlin/analysis/decompiler/stub/TypeClsStubBuilder.kt

@@ -21,10 +21,7 @@ import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.stubs.KotlinUserTypeStub
 import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes
 import org.jetbrains.kotlin.psi.stubs.impl.*
-import org.jetbrains.kotlin.serialization.deserialization.DYNAMIC_TYPE_DESERIALIZER_ID
+import org.jetbrains.kotlin.serialization.deserialization.*
-import org.jetbrains.kotlin.serialization.deserialization.ProtoContainer
-import org.jetbrains.kotlin.serialization.deserialization.getClassId
-import org.jetbrains.kotlin.serialization.deserialization.getName
 import org.jetbrains.kotlin.utils.doNothing
 
 // TODO: see DescriptorRendererOptions.excludedTypeAnnotationClasses for decompiler
@@ -70,18 +67,23 @@ class TypeClsStubBuilder(private val c: ClsStubBuilderContext) {
 
     private fun createTypeParameterStub(parent: KotlinStubBaseImpl<*>, type: Type, name: Name, annotations: List<ClassIdWithTarget>) {
         createTypeAnnotationStubs(parent, type, annotations)
+        val upperBoundType = if (type.hasFlexibleTypeCapabilitiesId()) {
+            createKotlinTypeBean(type.flexibleUpperBound(c.typeTable)!!)
+        } else null
+
+        val typeParameterClassId = ClassId.topLevel(FqName.topLevel(name))
         if (Flags.DEFINITELY_NOT_NULL_TYPE.get(type.flags)) {
-            createDefinitelyNotNullTypeStub(parent, FqName.topLevel(name))
+            createDefinitelyNotNullTypeStub(parent, typeParameterClassId, upperBoundType)
         } else {
             val nullableParentWrapper = nullableTypeParent(parent, type)
-            createStubForTypeName(ClassId.topLevel(FqName.topLevel(name)), nullableParentWrapper)
+            createStubForTypeName(typeParameterClassId, nullableParentWrapper, { upperBoundType })
         }
     }
 
-    private fun createDefinitelyNotNullTypeStub(parent: KotlinStubBaseImpl<*>, name: FqName) {
+    private fun createDefinitelyNotNullTypeStub(parent: KotlinStubBaseImpl<*>, classId: ClassId, upperBoundType: KotlinTypeBean?) {
         val intersectionType = KotlinPlaceHolderStubImpl<KtIntersectionType>(parent, KtStubElementTypes.INTERSECTION_TYPE)
         val leftReference = KotlinPlaceHolderStubImpl<KtTypeReference>(intersectionType, KtStubElementTypes.TYPE_REFERENCE)
-        createStubForTypeName(ClassId.topLevel(name), leftReference)
+        createStubForTypeName(classId, leftReference, { upperBoundType })
         val rightReference = KotlinPlaceHolderStubImpl<KtTypeReference>(intersectionType, KtStubElementTypes.TYPE_REFERENCE)
         val userType = KotlinUserTypeStubImpl(rightReference)
         KotlinNameReferenceExpressionStubImpl(userType, StandardNames.FqNames.any.shortName().ref())
@@ -129,11 +131,53 @@ class TypeClsStubBuilder(private val c: ClsStubBuilderContext) {
 
         val outerTypeChain = generateSequence(type) { it.outerType(c.typeTable) }.toList()
 
-        createStubForTypeName(classId, nullableTypeParent(parent, type)) { userTypeStub, index ->
+        createStubForTypeName(classId, nullableTypeParent(parent, type), { level ->
+            if (level == 0) createKotlinTypeBean(type.flexibleUpperBound(c.typeTable))
+            else createKotlinTypeBean(outerTypeChain.getOrNull(level)?.flexibleUpperBound(c.typeTable))
+        }) { userTypeStub, index ->
             outerTypeChain.getOrNull(index)?.let { createTypeArgumentListStub(userTypeStub, it.argumentList) }
         }
     }
 
+    private fun createKotlinTypeBean(
+        type: Type?
+    ): KotlinTypeBean? {
+        if (type == null) return null
+        val definitelyNotNull = Flags.DEFINITELY_NOT_NULL_TYPE.get(type.flags)
+        val lowerBound = when {
+            type.hasTypeParameter() -> {
+                val lowerBound = KotlinTypeParameterTypeBean(
+                    c.typeParameters[type.typeParameter].asString(),
+                    type.nullable,
+                    definitelyNotNull
+                )
+                lowerBound
+            }
+            type.hasTypeParameterName() -> {
+                KotlinTypeParameterTypeBean(
+                    c.nameResolver.getString(type.typeParameterName),
+                    type.nullable,
+                    definitelyNotNull
+                )
+            }
+            else -> {
+                val classId = c.nameResolver.getClassId(if (type.hasClassName()) type.className else type.typeAliasName)
+                val arguments = type.argumentList.map { argument ->
+                    val kind = argument.projection.toProjectionKind()
+                    KotlinTypeArgumentBean(
+                        kind,
+                        if (kind == KtProjectionKind.STAR) null else createKotlinTypeBean(argument.type(c.typeTable))
+                    )
+                }
+                KotlinClassTypeBean(classId, arguments, type.nullable)
+            }
+        }
+        val upperBoundBean = createKotlinTypeBean(type.flexibleUpperBound(c.typeTable))
+        return if (upperBoundBean != null) {
+            KotlinFlexibleTypeBean(lowerBound, upperBoundBean)
+        } else lowerBound
+    }
+
     private fun createTypeAnnotationStubs(parent: KotlinStubBaseImpl<*>, type: Type, annotations: List<ClassIdWithTarget>) {
         val typeModifiers = getTypeModifiersAsWritten(type)
         if (annotations.isEmpty() && typeModifiers.isEmpty()) return

analysis/decompiled/decompiler-to-stubs/src/org/jetbrains/kotlin/analysis/decompiler/stub/clsStubBuilding.kt

@@ -131,6 +131,7 @@ fun createStubForPackageName(packageDirectiveStub: KotlinPlaceHolderStubImpl<KtP
 fun createStubForTypeName(
     typeClassId: ClassId,
     parent: StubElement<out PsiElement>,
+    upperBoundFun: ((Int) -> KotlinTypeBean?)? = null,
     bindTypeArguments: (KotlinUserTypeStub, Int) -> Unit = { _, _ -> }
 ): KotlinUserTypeStub {
     val substituteWithAny = typeClassId.isLocal
@@ -143,7 +144,7 @@ fun createStubForTypeName(
 
     fun recCreateStubForType(current: StubElement<out PsiElement>, level: Int): KotlinUserTypeStub {
         val lastSegment = segments[level]
-        val userTypeStub = KotlinUserTypeStubImpl(current)
+        val userTypeStub = KotlinUserTypeStubImpl(current, upperBoundFun?.invoke(level))
         if (level + 1 < segments.size) {
             recCreateStubForType(userTypeStub, level + 1)
         }

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/KotlinStubVersions.kt

@@ -28,7 +28,7 @@ object KotlinStubVersions {
     // Binary stub version should be increased if stub format (org.jetbrains.kotlin.psi.stubs.impl) is changed
     //      or changes are made to the core stub building code (org.jetbrains.kotlin.idea.decompiler.stubBuilder).
     // Increasing this version will lead to reindexing of all binary files that are potentially kotlin binaries (including all class files).
-    private const val BINARY_STUB_VERSION = 83
+    private const val BINARY_STUB_VERSION = 84
 
     // Classfile stub version should be increased if changes are made to classfile stub building subsystem (org.jetbrains.kotlin.idea.decompiler.classFile)
     // Increasing this version will lead to reindexing of all classfiles.

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/elements/KtUserTypeElementType.java

@@ -21,9 +21,18 @@ import com.intellij.psi.stubs.StubInputStream;
 import com.intellij.psi.stubs.StubOutputStream;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.kotlin.name.ClassId;
+import org.jetbrains.kotlin.psi.KtProjectionKind;
 import org.jetbrains.kotlin.psi.KtUserType;
 import org.jetbrains.kotlin.psi.stubs.KotlinUserTypeStub;
-import org.jetbrains.kotlin.psi.stubs.impl.KotlinUserTypeStubImpl;
+import org.jetbrains.kotlin.psi.stubs.StubUtils;
+import org.jetbrains.kotlin.psi.stubs.impl.*;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
 
 public class KtUserTypeElementType extends KtStubElementType<KotlinUserTypeStub, KtUserType> {
     public KtUserTypeElementType(@NotNull @NonNls String debugName) {
@@ -33,16 +42,92 @@ public class KtUserTypeElementType extends KtStubElementType<KotlinUserTypeStub,
     @NotNull
     @Override
     public KotlinUserTypeStub createStub(@NotNull KtUserType psi, StubElement parentStub) {
-        return new KotlinUserTypeStubImpl((StubElement<?>) parentStub);
+        return new KotlinUserTypeStubImpl((StubElement<?>) parentStub, null);
     }
 
     @Override
-    public void serialize(@NotNull KotlinUserTypeStub stub, @NotNull StubOutputStream dataStream) {
+    public void serialize(@NotNull KotlinUserTypeStub stub, @NotNull StubOutputStream dataStream) throws IOException {
+        serializeType(dataStream, ((KotlinUserTypeStubImpl) stub).getUpperBound());
+    }
+
+    private enum KotlinTypeBeanKind {
+        CLASS, TYPE_PARAMETER, FLEXIBLE, NONE;
+
+        static KotlinTypeBeanKind fromBean(@Nullable KotlinTypeBean typeBean) {
+            if (typeBean == null) return NONE;
+            if (typeBean instanceof KotlinTypeParameterTypeBean) return TYPE_PARAMETER;
+            if (typeBean instanceof KotlinClassTypeBean) return CLASS;
+            return FLEXIBLE;
+        }
+    }
+
+    private static void serializeType(@NotNull StubOutputStream dataStream, @Nullable KotlinTypeBean type) throws IOException {
+        dataStream.writeInt(KotlinTypeBeanKind.fromBean(type).ordinal());
+        if (type instanceof KotlinClassTypeBean) {
+            StubUtils.serializeClassId(dataStream, ((KotlinClassTypeBean) type).getClassId());
+            dataStream.writeBoolean(type.getNullable());
+            List<KotlinTypeArgumentBean> arguments = ((KotlinClassTypeBean) type).getArguments();
+            dataStream.writeInt(arguments.size());
+            for (KotlinTypeArgumentBean argument : arguments) {
+                KtProjectionKind kind = argument.getProjectionKind();
+                dataStream.writeInt(kind.ordinal());
+                if (kind != KtProjectionKind.STAR) {
+                    serializeType(dataStream, argument.getType());
+                }
+            }
+        }
+        else if (type instanceof KotlinTypeParameterTypeBean) {
+            dataStream.writeName(((KotlinTypeParameterTypeBean) type).getTypeParameterName());
+            dataStream.writeBoolean(type.getNullable());
+            dataStream.writeBoolean(((KotlinTypeParameterTypeBean) type).getDefinitelyNotNull());
+        }
+        else if (type instanceof KotlinFlexibleTypeBean) {
+            serializeType(dataStream, ((KotlinFlexibleTypeBean) type).getLowerBound());
+            serializeType(dataStream, ((KotlinFlexibleTypeBean) type).getUpperBound());
+        }
     }
 
     @NotNull
     @Override
-    public KotlinUserTypeStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) {
+    public KotlinUserTypeStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
-        return new KotlinUserTypeStubImpl((StubElement<?>) parentStub);
+        return new KotlinUserTypeStubImpl((StubElement<?>) parentStub, deserializeType(dataStream));
+    }
+
+    @Nullable
+    private static KotlinTypeBean deserializeType(@NotNull StubInputStream dataStream) throws IOException {
+        KotlinTypeBeanKind typeKind = KotlinTypeBeanKind.values()[dataStream.readInt()];
+        switch (typeKind) {
+            case CLASS: {
+                ClassId classId = Objects.requireNonNull(StubUtils.deserializeClassId(dataStream));
+                boolean isNullable = dataStream.readBoolean();
+                int count = dataStream.readInt();
+                List<KotlinTypeArgumentBean> arguments = new ArrayList<>();
+                for (int i = 0; i < count; i++) {
+                    int kind = dataStream.readInt();
+                    KotlinTypeArgumentBean argument;
+                    if (kind != KtProjectionKind.STAR.ordinal()) {
+                        argument = new KotlinTypeArgumentBean(KtProjectionKind.values()[kind], deserializeType(dataStream));
+                    }
+                    else {
+                        argument = new KotlinTypeArgumentBean(KtProjectionKind.STAR, null);
+                    }
+                    arguments.add(argument);
+                }
+                return new KotlinClassTypeBean(classId, arguments, isNullable);
+            }
+            case TYPE_PARAMETER: {
+                String typeParameterName = Objects.requireNonNull(dataStream.readNameString());
+                boolean nullable = dataStream.readBoolean();
+                boolean definitelyNotNull = dataStream.readBoolean();
+                return new KotlinTypeParameterTypeBean(typeParameterName, nullable, definitelyNotNull);
+            }
+            case FLEXIBLE: {
+                return new KotlinFlexibleTypeBean(Objects.requireNonNull(deserializeType(dataStream)),
+                                                  Objects.requireNonNull(deserializeType(dataStream)));
+            }
+            case NONE:
+                return null;
+        }
+        return null;
     }
 }

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinUserTypeStubImpl.kt

@@ -18,10 +18,36 @@ package org.jetbrains.kotlin.psi.stubs.impl
 
 import com.intellij.psi.PsiElement
 import com.intellij.psi.stubs.StubElement
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.psi.KtProjectionKind
 import org.jetbrains.kotlin.psi.KtUserType
 import org.jetbrains.kotlin.psi.stubs.KotlinUserTypeStub
 import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes
 
 class KotlinUserTypeStubImpl(
-    parent: StubElement<out PsiElement>?
+    parent: StubElement<out PsiElement>?,
+    val upperBound: KotlinTypeBean? = null
 ) : KotlinStubBaseImpl<KtUserType>(parent, KtStubElementTypes.USER_TYPE), KotlinUserTypeStub
+
+sealed interface KotlinTypeBean {
+    val nullable: Boolean
+}
+
+data class KotlinFlexibleTypeBean(val lowerBound: KotlinTypeBean, val upperBound: KotlinTypeBean) : KotlinTypeBean {
+    override val nullable: Boolean
+        get() = lowerBound.nullable
+}
+
+data class KotlinClassTypeBean(
+    val classId: ClassId,
+    val arguments: List<KotlinTypeArgumentBean>,
+    override val nullable: Boolean,
+) : KotlinTypeBean
+
+data class KotlinTypeArgumentBean(val projectionKind: KtProjectionKind, val type: KotlinTypeBean?)
+
+data class KotlinTypeParameterTypeBean(
+    val typeParameterName: String,
+    override val nullable: Boolean,
+    val definitelyNotNull: Boolean
+) : KotlinTypeBean

generators/analysis-api-generator/tests/org/jetbrains/kotlin/generators/tests/analysis/api/decompiled.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.generators.tests.analysis.api
 
 import org.jetbrains.kotlin.analysis.decompiler.psi.AbstractByDecompiledPsiStubBuilderTest
+import org.jetbrains.kotlin.analysis.decompiler.stub.files.AbstractAdditionalStubInfoTest
 import org.jetbrains.kotlin.analysis.decompiler.stub.files.AbstractClsStubBuilderTest
 import org.jetbrains.kotlin.generators.TestGroupSuite
 
@@ -19,6 +20,15 @@ internal fun TestGroupSuite.generateDecompiledTests() {
         }
     }
 
+    testGroup(
+        "analysis/decompiled/decompiler-to-file-stubs/tests",
+        "analysis/decompiled/decompiler-to-file-stubs/testData",
+    ) {
+        testClass<AbstractAdditionalStubInfoTest> {
+            model("additionalClsStubInfo", extension = null, recursive = false)
+        }
+    }
+
     testGroup(
         "analysis/decompiled/decompiler-to-psi/tests",
         "analysis/decompiled/decompiler-to-file-stubs/testData",