IR KT-44233 support flexible nullability in IrTypeSystemContext

^KT-44233 Fixed Target versions 1.5-M1

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

@@ -33,7 +33,16 @@ interface IrTypeSystemContext : TypeSystemContext, TypeSystemCommonSuperTypesCon
 
     override fun KotlinTypeMarker.asSimpleType() = this as? SimpleTypeMarker
 
-    override fun KotlinTypeMarker.asFlexibleType() = this as? IrDynamicType
+    override fun KotlinTypeMarker.asFlexibleType(): FlexibleTypeMarker? {
+        if (this is FlexibleTypeMarker) return this
+
+        if (this is IrType) {
+            val jvmFlexibleType = this.asJvmFlexibleType()
+            if (jvmFlexibleType != null) return jvmFlexibleType
+        }
+
+        return null
+    }
 
     override fun KotlinTypeMarker.isError() = this is IrErrorType
 
@@ -44,13 +53,19 @@ interface IrTypeSystemContext : TypeSystemContext, TypeSystemCommonSuperTypesCon
     override fun FlexibleTypeMarker.asRawType(): RawTypeMarker? = null
 
     override fun FlexibleTypeMarker.upperBound(): SimpleTypeMarker {
-        require(this is IrDynamicType)
-        return irBuiltIns.anyNType as IrSimpleType
+        return when (this) {
+            is IrDynamicType -> irBuiltIns.anyNType as IrSimpleType
+            is IrJvmFlexibleType -> this.upperBound
+            else -> error("Unexpected flexible type ${this::class.java.simpleName}: $this")
+        }
     }
 
     override fun FlexibleTypeMarker.lowerBound(): SimpleTypeMarker {
-        require(this is IrDynamicType)
-        return irBuiltIns.nothingType as IrSimpleType
+        return when (this) {
+            is IrDynamicType -> irBuiltIns.nothingType as IrSimpleType
+            is IrJvmFlexibleType -> this.lowerBound
+            else -> error("Unexpected flexible type ${this::class.java.simpleName}: $this")
+        }
     }
 
     override fun SimpleTypeMarker.asCapturedType(): CapturedTypeMarker? = null

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

@@ -21,7 +21,6 @@ import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
 import org.jetbrains.kotlin.ir.util.isAnonymousObject
 import org.jetbrains.kotlin.ir.util.isPropertyAccessor
 import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.types.*
 import org.jetbrains.kotlin.types.typeUtil.makeNotNullable
 import org.jetbrains.kotlin.types.typeUtil.makeNullable
@@ -30,19 +29,21 @@ import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 fun IrType.withHasQuestionMark(newHasQuestionMark: Boolean): IrType =
     when (this) {
-        is IrSimpleType ->
-            if (this.hasQuestionMark == newHasQuestionMark)
-                this
-            else
-                buildSimpleType {
-                    hasQuestionMark = newHasQuestionMark
-                    kotlinType = originalKotlinType?.run {
-                        if (newHasQuestionMark) makeNullable() else makeNotNullable()
-                    }
-                }
+        is IrSimpleType -> withHasQuestionMark(newHasQuestionMark)
         else -> this
     }
 
+fun IrSimpleType.withHasQuestionMark(newHasQuestionMark: Boolean): IrSimpleType =
+    if (this.hasQuestionMark == newHasQuestionMark)
+        this
+    else
+        buildSimpleType {
+            hasQuestionMark = newHasQuestionMark
+            kotlinType = originalKotlinType?.run {
+                if (newHasQuestionMark) makeNullable() else makeNotNullable()
+            }
+        }
+
 fun IrType.addAnnotations(newAnnotations: List<IrConstructorCall>): IrType =
     if (newAnnotations.isEmpty())
         this

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2010-2021 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.ir.types
+
+import org.jetbrains.kotlin.ir.util.hasAnnotation
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.types.model.FlexibleTypeMarker
+import org.jetbrains.kotlin.types.model.SimpleTypeMarker
+
+internal interface IrJvmFlexibleType : FlexibleTypeMarker {
+    val lowerBound: SimpleTypeMarker
+    val upperBound: SimpleTypeMarker
+}
+
+internal class IrJvmFlexibleNullabilityType(val irType: IrSimpleType) : IrJvmFlexibleType {
+    override val lowerBound get() = irType.withHasQuestionMark(false)
+    override val upperBound get() = irType.withHasQuestionMark(true)
+}
+
+internal val FLEXIBLE_NULLABILITY_FQN = FqName("kotlin.internal.ir").child(Name.identifier("FlexibleNullability"))
+
+internal fun IrType.isWithFlexibleNullability() =
+    hasAnnotation(FLEXIBLE_NULLABILITY_FQN)
+
+internal fun IrType.asJvmFlexibleType() =
+    when {
+        this is IrSimpleType && isWithFlexibleNullability() ->
+            IrJvmFlexibleNullabilityType(
+                this.removeAnnotations { irCtorCall ->
+                    irCtorCall.type.classFqName == FLEXIBLE_NULLABILITY_FQN
+                } as IrSimpleType
+            )
+        else ->
+            null
+    }