[IR] Introduce IrDefinitelyNotNullType in IR

- support it in render
 - support in IR copy
 - KEEP-268

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrType.kt

@@ -30,6 +30,10 @@ interface IrErrorType : IrType
 
 interface IrDynamicType : IrType, DynamicTypeMarker
 
+interface IrDefinitelyNotNullType : IrType, DefinitelyNotNullTypeMarker {
+    val original: IrType
+}
+
 interface IrSimpleType : IrType, SimpleTypeMarker, TypeArgumentListMarker {
     val classifier: IrClassifierSymbol
     val hasQuestionMark: Boolean

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeUtils.kt

@@ -34,6 +34,7 @@ fun IrType.isSubtypeOf(superType: IrType, typeSystem: IrTypeSystemContext): Bool
 
 fun IrType.isNullable(): Boolean =
     when (this) {
+        is IrDefinitelyNotNullType -> false
         is IrSimpleType -> when (val classifier = classifier) {
             is IrClassSymbol -> hasQuestionMark
             is IrTypeParameterSymbol -> hasQuestionMark || classifier.owner.superTypes.any(IrType::isNullable)

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/impl/IrSimpleTypeImpl.kt

@@ -35,7 +35,7 @@ abstract class IrAbstractSimpleType(kotlinType: KotlinType?) : IrTypeBase(kotlin
                 arguments.hashCode()
 }
 
-abstract class IrDelegatedSimpleType : IrAbstractSimpleType(null) {
+abstract class IrDelegatedSimpleType(kotlinType: KotlinType? = null) : IrAbstractSimpleType(kotlinType) {
 
     protected abstract val delegate: IrSimpleType
 
@@ -51,6 +51,14 @@ abstract class IrDelegatedSimpleType : IrAbstractSimpleType(null) {
         get() = delegate.annotations
 }
 
+// TODO: This implementation is aligned with FE representation of DefinitelyNotNull (DNN) type but
+//       in fact DNN is special case of more general `IntersectionType`
+//       so someday it should be reconsidered
+class IrDefinitelyNotNullTypeImpl(kotlinType: KotlinType?, original: IrType) : IrDelegatedSimpleType(kotlinType), IrDefinitelyNotNullType {
+    override val delegate: IrSimpleType = original as IrSimpleType
+    override val original: IrType
+        get() = delegate
+}
 
 class IrSimpleTypeImpl(
     kotlinType: KotlinType?,
@@ -123,6 +131,7 @@ class IrTypeProjectionImpl internal constructor(
 fun makeTypeProjection(type: IrType, variance: Variance): IrTypeProjection =
     when {
         type is IrCapturedType -> IrTypeProjectionImpl(type, variance)
+        type is IrDefinitelyNotNullType -> IrTypeProjectionImpl(type, variance)
         type is IrTypeProjection && type.variance == variance -> type
         type is IrSimpleType -> type.toBuilder().apply { this.variance = variance }.buildTypeProjection()
         type is IrDynamicType -> IrDynamicTypeImpl(null, type.annotations, variance)

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeepCopyTypeRemapper.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.ir.util
 import org.jetbrains.kotlin.ir.declarations.IrTypeParametersContainer
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.types.*
+import org.jetbrains.kotlin.ir.types.impl.IrDefinitelyNotNullTypeImpl
 import org.jetbrains.kotlin.ir.types.impl.IrSimpleTypeImpl
 import org.jetbrains.kotlin.ir.types.impl.IrTypeAbbreviationImpl
 import org.jetbrains.kotlin.ir.types.impl.makeTypeProjection
@@ -26,11 +27,10 @@ class DeepCopyTypeRemapper(
         // TODO
     }
 
-    override fun remapType(type: IrType): IrType =
-        if (type !is IrSimpleType)
-            type
-        else
-            IrSimpleTypeImpl(
+    override fun remapType(type: IrType): IrType {
+        return when (type) {
+            is IrDefinitelyNotNullType -> IrDefinitelyNotNullTypeImpl(null, remapType(type.original))
+            is IrSimpleType -> IrSimpleTypeImpl(
                 null,
                 symbolRemapper.getReferencedClassifier(type.classifier),
                 type.hasQuestionMark,
@@ -38,6 +38,9 @@ class DeepCopyTypeRemapper(
                 type.annotations.map { it.transform(deepCopy, null) as IrConstructorCall },
                 type.abbreviation?.remapTypeAbbreviation()
             )
+            else -> type
+        }
+    }
 
     private fun remapTypeArgument(typeArgument: IrTypeArgument): IrTypeArgument =
         if (typeArgument is IrTypeProjection)

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/RenderIrElement.kt

@@ -113,6 +113,8 @@ class RenderIrElementVisitor(private val normalizeNames: Boolean = false, privat
 
             is IrErrorType -> "IrErrorType(${if (verboseErrorTypes) originalKotlinType else null})"
 
+            is IrDefinitelyNotNullType -> "{${original.render()} & Any}"
+
             is IrSimpleType -> buildTrimEnd {
                 append(classifier.renderClassifierFqn())
                 if (arguments.isNotEmpty()) {

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/dumpKotlinLike.kt

@@ -6,7 +6,10 @@
 package org.jetbrains.kotlin.ir.util
 
 import com.intellij.openapi.util.text.StringUtil
-import org.jetbrains.kotlin.descriptors.*
+import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
+import org.jetbrains.kotlin.descriptors.DescriptorVisibility
+import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.*
@@ -415,6 +418,11 @@ private class KotlinLikeDumper(val p: Printer, val options: KotlinLikeDumpOption
         // TODO don't print `Any?` as upper bound?
         printAnnotationsWithNoIndent()
         when (this) {
+            is IrDefinitelyNotNullType -> {
+                p.printWithNoIndent("(")
+                original.printTypeWithNoIndent()
+                p.printWithNoIndent(" & Any)")
+            }
             is IrSimpleType -> {
                 // TODO abbreviation