Add KType.arguments and support 'typeOf' intrinsic

#KT-29917 Fixed
 #KT-28625 Fixed

Also perform minor refactoring.

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/KonanReflectionTypes.kt

@@ -41,6 +41,7 @@ class KonanReflectionTypes(module: ModuleDescriptor, internalPackage: FqName) {
     val kMutableProperty0: ClassDescriptor by ClassLookup(kotlinReflectScope)
     val kMutableProperty1: ClassDescriptor by ClassLookup(kotlinReflectScope)
     val kMutableProperty2: ClassDescriptor by ClassLookup(kotlinReflectScope)
+    val kTypeProjection: ClassDescriptor by ClassLookup(kotlinReflectScope)
 
     val kFunctionImpl: ClassDescriptor by ClassLookup(internalScope)
     val kProperty0Impl: ClassDescriptor by ClassLookup(internalScope)

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/Ir.kt

@@ -20,7 +20,6 @@ import org.jetbrains.kotlin.config.languageVersionSettings
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
 import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
@@ -30,8 +29,10 @@ import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.resolve.calls.components.isVararg
+import org.jetbrains.kotlin.resolve.scopes.MemberScope
 import org.jetbrains.kotlin.types.KotlinType
-import org.jetbrains.kotlin.types.TypeUtils
+import org.jetbrains.kotlin.types.Variance
 import kotlin.properties.Delegates
 
 // This is what Context collects about IR.
@@ -249,8 +250,11 @@ internal class KonanSymbols(context: Context, private val symbolTable: SymbolTab
             { findArrayExtension(it.descriptor, "contentHashCode") }
     )
 
+    private val kotlinCollectionsPackageScope: MemberScope
+        get() = builtInsPackage("kotlin", "collections")
+
     private fun findArrayExtension(descriptor: ClassDescriptor, name: String): IrSimpleFunctionSymbol {
-        val functionDescriptor = builtInsPackage("kotlin", "collections")
+        val functionDescriptor = kotlinCollectionsPackageScope
                 .getContributedFunctions(Name.identifier(name), NoLookupLocation.FROM_BACKEND)
                 .singleOrNull {
                     it.valueParameters.isEmpty()
@@ -403,6 +407,41 @@ internal class KonanSymbols(context: Context, private val symbolTable: SymbolTab
     val kTypeImpl = internalClass("KTypeImpl")
     val kTypeImplForGenerics = internalClass("KTypeImplForGenerics")
 
+    val kTypeProjection = symbolTable.referenceClass(context.reflectionTypes.kTypeProjection)
+
+    private val kTypeProjectionCompanionDescriptor = context.reflectionTypes.kTypeProjection.companionObjectDescriptor!!
+
+    val kTypeProjectionCompanion = symbolTable.referenceClass(kTypeProjectionCompanionDescriptor)
+
+    val kTypeProjectionStar = symbolTable.referenceProperty(
+            kTypeProjectionCompanionDescriptor.unsubstitutedMemberScope
+                    .getContributedVariables(Name.identifier("STAR"), NoLookupLocation.FROM_BACKEND).single()
+    )
+
+    val kTypeProjectionFactories: Map<Variance, IrSimpleFunctionSymbol> = Variance.values().toList().associateWith {
+        val factoryName = when (it) {
+            Variance.INVARIANT -> "invariant"
+            Variance.IN_VARIANCE -> "contravariant"
+            Variance.OUT_VARIANCE -> "covariant"
+        }
+
+        symbolTable.referenceSimpleFunction(
+                kTypeProjectionCompanionDescriptor.unsubstitutedMemberScope
+                        .getContributedFunctions(Name.identifier(factoryName), NoLookupLocation.FROM_BACKEND).single()
+        )
+    }
+
+    val emptyList = symbolTable.referenceSimpleFunction(
+            kotlinCollectionsPackageScope
+                    .getContributedFunctions(Name.identifier("emptyList"), NoLookupLocation.FROM_BACKEND)
+                    .single { it.valueParameters.isEmpty() }
+    )
+
+    val listOf = symbolTable.referenceSimpleFunction(
+            kotlinCollectionsPackageScope
+                    .getContributedFunctions(Name.identifier("listOf"), NoLookupLocation.FROM_BACKEND)
+                    .single { it.valueParameters.size == 1 && it.valueParameters[0].isVararg }
+    )
     val listOfInternal = internalFunction("listOfInternal")
 
     val threadLocal =

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/CallableReferenceLowering.kt

@@ -40,6 +40,8 @@ internal class CallableReferenceLowering(val context: Context): FileLoweringPass
 
     private object DECLARATION_ORIGIN_FUNCTION_REFERENCE_IMPL : IrDeclarationOriginImpl("FUNCTION_REFERENCE_IMPL")
 
+    private val kTypeGenerator = KTypeGenerator(context)
+
     override fun lower(irFile: IrFile) {
         var generatedClasses = mutableListOf<IrClass>()
         irFile.transform(object: IrElementTransformerVoidWithContext() {
@@ -266,7 +268,7 @@ internal class CallableReferenceLowering(val context: Context): FileLoweringPass
                         val needReceiver = boundFunctionParameters.singleOrNull()?.descriptor is ReceiverParameterDescriptor
                         val receiver = if (needReceiver) irGet(valueParameters.single()) else irNull()
                         putValueArgument(3, receiver)
-                        putValueArgument(4, irKType(this@CallableReferenceLowering.context, referencedFunction.returnType))
+                        putValueArgument(4, with(kTypeGenerator) { irKType(referencedFunction.returnType) })
                     }
                     +IrInstanceInitializerCallImpl(startOffset, endOffset, functionReferenceClass.symbol, irBuiltIns.unitType)
                     // Save all arguments to fields.

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/DelegationLowering.kt

@@ -34,6 +34,8 @@ import org.jetbrains.kotlin.name.Name
 internal class PropertyDelegationLowering(val context: Context) : FileLoweringPass {
     private var tempIndex = 0
 
+    private val kTypeGenerator = KTypeGenerator(context)
+
     private fun getKPropertyImplConstructor(receiverTypes: List<IrType>,
                                             returnType: IrType,
                                             isLocal: Boolean,
@@ -253,7 +255,7 @@ internal class PropertyDelegationLowering(val context: Context) : FileLoweringPa
                     isMutable     = setterCallableReference != null)
             val initializer = irCall(symbol.owner, constructorTypeArguments).apply {
                 putValueArgument(0, irString(propertyDescriptor.name.asString()))
-                putValueArgument(1, irKType(this@PropertyDelegationLowering.context, returnType))
+                putValueArgument(1, with(kTypeGenerator) { irKType(returnType) })
                 if (getterCallableReference != null)
                     putValueArgument(2, getterCallableReference)
                 if (setterCallableReference != null)
@@ -274,7 +276,7 @@ internal class PropertyDelegationLowering(val context: Context) : FileLoweringPa
                     isMutable = false)
             val initializer = irCall(symbol.owner, constructorTypeArguments).apply {
                 putValueArgument(0, irString(propertyDescriptor.name.asString()))
-                putValueArgument(1, irKType(this@PropertyDelegationLowering.context, propertyType))
+                putValueArgument(1, with(kTypeGenerator) { irKType(propertyType) })
             }
             return initializer
         }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/FunctionInlining.kt

@@ -47,6 +47,8 @@ internal class FunctionInlining(val context: Context) : IrElementTransformerVoid
             return expression
         if (Symbols.isLateinitIsInitializedPropertyGetter(callee.symbol))
             return expression
+        if (callee.isTypeOfIntrinsic())
+            return expression
 
         val actualCallee = getFunctionDeclaration(callee.symbol)
 

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/PostInlineLowering.kt

@@ -9,12 +9,16 @@ import org.jetbrains.kotlin.backend.common.FileLoweringPass
 import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.konan.Context
+import org.jetbrains.kotlin.backend.konan.error
 import org.jetbrains.kotlin.backend.konan.ir.typeWithoutArguments
 import org.jetbrains.kotlin.backend.konan.reportCompilationError
+import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
+import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.util.irCall
+import org.jetbrains.kotlin.ir.util.isTypeOfIntrinsic
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 
 /**
@@ -26,23 +30,32 @@ internal class PostInlineLowering(val context: Context) : FileLoweringPass {
 
     private val symbols get() = context.ir.symbols
 
+    private val kTypeGenerator = KTypeGenerator(
+            context,
+            eraseTypeParameters = true // Mimic JVM BE behaviour until proper type parameter impl is ready.
+    )
+
     override fun lower(irFile: IrFile) {
         irFile.transformChildrenVoid(object : IrElementTransformerVoidWithContext() {
 
             override fun visitClassReference(expression: IrClassReference): IrExpression {
                 expression.transformChildrenVoid()
 
-                val builder = context.createIrBuilder(currentScope!!.scope.scopeOwnerSymbol,
+                val builder = createIrBuilder(expression)
-                        expression.startOffset, expression.endOffset)
 
-                return builder.irKClass(context, expression.symbol)
+                val symbol = expression.symbol
+                return if (symbol is IrClassSymbol) {
+                    builder.irKClass(context, symbol)
+                } else {
+                    // E.g. for `T::class` in a body of an inline function itself.
+                    builder.irCall(context.ir.symbols.ThrowNullPointerException.owner)
+                }
             }
 
             override fun visitGetClass(expression: IrGetClass): IrExpression {
                 expression.transformChildrenVoid()
 
-                val builder = context.createIrBuilder(currentScope!!.scope.scopeOwnerSymbol,
+                val builder = createIrBuilder(expression)
-                        expression.startOffset, expression.endOffset)
 
                 val typeArgument = expression.argument.type
 
@@ -91,10 +104,20 @@ internal class PostInlineLowering(val context: Context) : FileLoweringPass {
                             expression.startOffset, expression.endOffset,
                             context.ir.symbols.immutableBlob.typeWithoutArguments,
                             IrConstKind.String, builder.toString()))
+                } else if (expression.symbol.owner.isTypeOfIntrinsic()) {
+                    val type = expression.getTypeArgument(0)
+                            ?: error(irFile, expression, "missing type argument")
+                    return with (kTypeGenerator) { createIrBuilder(expression).irKType(type) }
                 }
 
                 return expression
             }
+
+            private fun createIrBuilder(element: IrElement) = context.createIrBuilder(
+                    currentScope!!.scope.scopeOwnerSymbol,
+                    element.startOffset,
+                    element.endOffset
+            )
         })
     }
 }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/ReflectionSupport.kt

@@ -8,50 +8,102 @@ package org.jetbrains.kotlin.backend.konan.lower
 import org.jetbrains.kotlin.backend.konan.InteropFqNames
 import org.jetbrains.kotlin.backend.konan.KonanBackendContext
 import org.jetbrains.kotlin.backend.konan.ir.typeWithStarProjections
+import org.jetbrains.kotlin.backend.konan.ir.typeWithoutArguments
 import org.jetbrains.kotlin.backend.konan.isObjCClass
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
-import org.jetbrains.kotlin.ir.builders.IrBuilderWithScope
+import org.jetbrains.kotlin.ir.builders.*
-import org.jetbrains.kotlin.ir.builders.irBoolean
-import org.jetbrains.kotlin.ir.builders.irCall
-import org.jetbrains.kotlin.ir.builders.irString
 import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.IrMemberAccessExpression
+import org.jetbrains.kotlin.ir.expressions.impl.IrVarargImpl
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
-import org.jetbrains.kotlin.ir.symbols.IrClassifierSymbol
+import org.jetbrains.kotlin.ir.types.*
-import org.jetbrains.kotlin.ir.types.IrType
-import org.jetbrains.kotlin.ir.types.classifierOrNull
-import org.jetbrains.kotlin.ir.types.isMarkedNullable
 import org.jetbrains.kotlin.ir.util.constructors
 import org.jetbrains.kotlin.ir.util.irCall
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameUnsafe
 import org.jetbrains.kotlin.resolve.descriptorUtil.getAllSuperClassifiers
 
-internal fun IrBuilderWithScope.irKType(context: KonanBackendContext, type: IrType): IrExpression {
+internal class KTypeGenerator(
-    val kTypeImplSymbol = context.ir.symbols.kTypeImpl
+        private val context: KonanBackendContext,
-    val kTypeImplForGenericsSymbol = context.ir.symbols.kTypeImplForGenerics
+        private val eraseTypeParameters: Boolean = false
+) {
+    private val symbols = context.ir.symbols
 
-    val kTypeImplConstructorSymbol = kTypeImplSymbol.constructors.single()
+    fun IrBuilderWithScope.irKType(type: IrType): IrExpression = if (type !is IrSimpleType) {
-    val kTypeImplForGenericsConstructorSymbol = kTypeImplForGenericsSymbol.constructors.single()
+        // Represent as non-denotable type:
-
+        irKTypeImpl(
-    val classifierOrNull = type.classifierOrNull
+                kClassifier = irNull(),
-
+                irTypeArguments = emptyList(),
-    return if (classifierOrNull !is IrClassSymbol) {
+                isMarkedNullable = false
-        // IrTypeParameterSymbol
+        )
-        irCall(kTypeImplForGenericsConstructorSymbol)
     } else {
-        val returnKClass = irKClass(context, classifierOrNull)
+        val classifier = type.classifier
-        irCall(kTypeImplConstructorSymbol).apply {
+
-            putValueArgument(0, returnKClass)
+        if (classifier is IrClassSymbol) {
-            putValueArgument(1, irBoolean(type.isMarkedNullable()))
+            irKTypeImpl(
+                    kClassifier = irKClass(classifier),
+                    irTypeArguments = type.arguments,
+                    isMarkedNullable = type.hasQuestionMark
+            )
+        } else {
+            if (eraseTypeParameters) {
+                irKType(context.irBuiltIns.anyNType)
+            } else {
+                irCall(symbols.kTypeImplForGenerics.constructors.single())
+            }
+        }
+    }
+
+    private fun IrBuilderWithScope.irKTypeImpl(
+            kClassifier: IrExpression,
+            irTypeArguments: List<IrTypeArgument>,
+            isMarkedNullable: Boolean
+    ): IrExpression = irCall(symbols.kTypeImpl.constructors.single()).apply {
+        putValueArgument(0, kClassifier)
+        putValueArgument(1, irKTypeProjectionsList(irTypeArguments))
+        putValueArgument(2, irBoolean(isMarkedNullable))
+    }
+
+    private fun IrBuilderWithScope.irKClass(symbol: IrClassSymbol) = irKClass(this@KTypeGenerator.context, symbol)
+
+    private fun IrBuilderWithScope.irKTypeProjectionsList(
+            irTypeArguments: List<IrTypeArgument>
+    ): IrMemberAccessExpression {
+        val kTypeProjectionType = symbols.kTypeProjection.typeWithoutArguments
+
+        return if (irTypeArguments.isEmpty()) {
+            irCall(symbols.emptyList, listOf(kTypeProjectionType))
+        } else {
+            irCall(symbols.listOf, listOf(kTypeProjectionType)).apply {
+                putValueArgument(0, IrVarargImpl(
+                        startOffset,
+                        endOffset,
+                        type = symbols.array.typeWith(kTypeProjectionType),
+                        varargElementType = kTypeProjectionType,
+                        elements = irTypeArguments.map { irKTypeProjection(it) }
+                ))
+            }
+        }
+    }
+
+    private fun IrBuilderWithScope.irKTypeProjection(argument: IrTypeArgument): IrExpression {
+        return when (argument) {
+            is IrTypeProjection -> irCall(symbols.kTypeProjectionFactories.getValue(argument.variance)).apply {
+                dispatchReceiver = irGetObject(symbols.kTypeProjectionCompanion)
+                putValueArgument(0, irKType(argument.type))
+            }
+
+            is IrStarProjection -> irCall(symbols.kTypeProjectionStar.owner.getter!!).apply {
+                dispatchReceiver = irGetObject(symbols.kTypeProjectionCompanion)
+            }
+
+            else -> error("Unexpected IrTypeArgument: $argument (${argument::class})")
         }
     }
 }
 
-internal fun IrBuilderWithScope.irKClass(context: KonanBackendContext, symbol: IrClassifierSymbol): IrExpression {
+internal fun IrBuilderWithScope.irKClass(context: KonanBackendContext, symbol: IrClassSymbol): IrExpression {
     val symbols = context.ir.symbols
     return when {
-        symbol !is IrClassSymbol -> // E.g. for `T::class` in a body of an inline function itself.
-            irCall(symbols.ThrowNullPointerException.owner)
-
         symbol.descriptor.isObjCClass() ->
             irKClassUnsupported(context, "KClass for Objective-C classes is not supported yet")
 

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/ir/util/IrUtils2.kt

@@ -16,6 +16,7 @@ import org.jetbrains.kotlin.backend.konan.KonanCompilationException
 import org.jetbrains.kotlin.backend.konan.descriptors.synthesizedName
 import org.jetbrains.kotlin.backend.konan.ir.allParameters
 import org.jetbrains.kotlin.backend.konan.ir.containsNull
+import org.jetbrains.kotlin.builtins.KOTLIN_REFLECT_FQ_NAME
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
@@ -434,3 +435,8 @@ fun IrClass.defaultOrNullableType(hasQuestionMark: Boolean) =
 
 fun IrFunction.isRestrictedSuspendFunction(languageVersionSettings: LanguageVersionSettings): Boolean =
         this.descriptor.extensionReceiverParameter?.type?.isRestrictsSuspensionReceiver(languageVersionSettings) == true
+
+fun IrFunction.isTypeOfIntrinsic(): Boolean =
+        this.name.asString() == "typeOf" &&
+                this.valueParameters.isEmpty() &&
+                (this.parent as? IrPackageFragment)?.fqName == KOTLIN_REFLECT_FQ_NAME

runtime/src/main/kotlin/kotlin/native/internal/KTypeImpl.kt

@@ -5,15 +5,21 @@
 
 package kotlin.native.internal
 
-import kotlin.reflect.KClassifier
+import kotlin.reflect.*
-import kotlin.reflect.KType
 
-internal class KTypeImpl(override val classifier: KClassifier?, override val isMarkedNullable: Boolean) : KType {
+internal class KTypeImpl(
+        override val classifier: KClassifier?,
+        override val arguments: List<KTypeProjection>,
+        override val isMarkedNullable: Boolean
+) : KType {
     override fun equals(other: Any?) =
-            other is KTypeImpl && classifier == other.classifier && isMarkedNullable == other.isMarkedNullable
+            other is KTypeImpl &&
+                    this.classifier == other.classifier &&
+                    this.arguments == other.arguments &&
+                    this.isMarkedNullable == other.isMarkedNullable
 
     override fun hashCode(): Int {
-        return (classifier?.hashCode() ?: 0) * 31 + if (isMarkedNullable) 1 else 0
+        return (classifier?.hashCode() ?: 0) * 31 * 31 + this.arguments.hashCode() * 31 + if (isMarkedNullable) 1 else 0
     }
 }
 
@@ -21,6 +27,8 @@ internal class KTypeImplForGenerics : KType {
     override val classifier: KClassifier?
         get() = error("Generic types are not yet supported in reflection")
 
+    override val arguments: List<KTypeProjection> get() = emptyList()
+
     override val isMarkedNullable: Boolean
         get() = error("Generic types are not yet supported in reflection")
 

runtime/src/main/kotlin/kotlin/reflect/KType.kt

@@ -19,6 +19,17 @@ public interface KType {
     @SinceKotlin("1.1")
     public val classifier: KClassifier?
 
+    /**
+     * Type arguments passed for the parameters of the classifier in this type.
+     * For example, in the type `Array<out Number>` the only type argument is `out Number`.
+     *
+     * In case this type is based on an inner class, the returned list contains the type arguments provided for the innermost class first,
+     * then its outer class, and so on.
+     * For example, in the type `Outer<A, B>.Inner<C, D>` the returned list is `[C, D, A, B]`.
+     */
+    @SinceKotlin("1.1")
+    public val arguments: List<KTypeProjection>
+
     /**
      * `true` if this type was marked nullable in the source code.
      *
@@ -38,3 +49,56 @@ public interface KType {
      */
     public val isMarkedNullable: Boolean
 }
+
+/**
+ * Represents a type projection. Type projection is usually the argument to another type in a type usage.
+ * For example, in the type `Array<out Number>`, `out Number` is the covariant projection of the type represented by the class `Number`.
+ *
+ * Type projection is either the star projection, or an entity consisting of a specific type plus optional variance.
+ *
+ * See the [Kotlin language documentation](https://kotlinlang.org/docs/reference/generics.html#type-projections)
+ * for more information.
+ */
+@SinceKotlin("1.1")
+public data class KTypeProjection constructor(
+        /**
+         * The use-site variance specified in the projection, or `null` if this is a star projection.
+         */
+        public val variance: KVariance?,
+        /**
+         * The type specified in the projection, or `null` if this is a star projection.
+         */
+        public val type: KType?
+) {
+    public companion object {
+        /**
+         * Star projection, denoted by the `*` character.
+         * For example, in the type `KClass<*>`, `*` is the star projection.
+         * See the [Kotlin language documentation](https://kotlinlang.org/docs/reference/generics.html#star-projections)
+         * for more information.
+         */
+        public val STAR: KTypeProjection = KTypeProjection(null, null)
+
+        /**
+         * Creates an invariant projection of a given type. Invariant projection is just the type itself,
+         * without any use-site variance modifiers applied to it.
+         * For example, in the type `Set<String>`, `String` is an invariant projection of the type represented by the class `String`.
+         */
+        public fun invariant(type: KType): KTypeProjection =
+                KTypeProjection(KVariance.INVARIANT, type)
+
+        /**
+         * Creates a contravariant projection of a given type, denoted by the `in` modifier applied to a type.
+         * For example, in the type `MutableList<in Number>`, `in Number` is a contravariant projection of the type of class `Number`.
+         */
+        public fun contravariant(type: KType): KTypeProjection =
+                KTypeProjection(KVariance.IN, type)
+
+        /**
+         * Creates a covariant projection of a given type, denoted by the `out` modifier applied to a type.
+         * For example, in the type `Array<out Number>`, `out Number` is a covariant projection of the type of class `Number`.
+         */
+        public fun covariant(type: KType): KTypeProjection =
+                KTypeProjection(KVariance.OUT, type)
+    }
+}

runtime/src/main/kotlin/kotlin/reflect/KVariance.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package kotlin.reflect
+
+/**
+ * Represents variance applied to a type parameter on the declaration site (*declaration-site variance*),
+ * or to a type in a projection (*use-site variance*).
+ *
+ * See the [Kotlin language documentation](https://kotlinlang.org/docs/reference/generics.html#variance)
+ * for more information.
+ *
+ * @see [KTypeParameter.variance]
+ * @see [KTypeProjection]
+ */
+@SinceKotlin("1.1")
+enum class KVariance {
+    /**
+     * The affected type parameter or type is *invariant*, which means it has no variance applied to it.
+     */
+    INVARIANT,
+
+    /**
+     * The affected type parameter or type is *contravariant*. Denoted by the `in` modifier in the source code.
+     */
+    IN,
+
+    /**
+     * The affected type parameter or type is *covariant*. Denoted by the `out` modifier in the source code.
+     */
+    OUT,
+}