Support flexible types internally in typeOf

#KT-45066 Fixed

core/reflection.jvm/src/kotlin/reflect/jvm/internal/ReflectionFactoryImpl.java

@@ -146,6 +146,11 @@ public class ReflectionFactoryImpl extends ReflectionFactory {
         // Do nothing. KTypeParameterImpl implementation will load upper bounds from the metadata.
     }
 
+    // @Override // JPS
+    public KType platformType(KType lowerBound, KType upperBound) {
+        return TypeOfImplKt.createPlatformKType(lowerBound, upperBound);
+    }
+
     // Misc
 
     public static void clearCaches() {

core/reflection.jvm/src/kotlin/reflect/jvm/internal/typeOfImpl.kt

@@ -0,0 +1,21 @@
+/*
+ * 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 kotlin.reflect.jvm.internal
+
+import org.jetbrains.kotlin.types.KotlinTypeFactory
+import org.jetbrains.kotlin.types.SimpleType
+import kotlin.reflect.KType
+
+internal fun createPlatformKType(lowerBound: KType, upperBound: KType): KType {
+    // lowerBound/upperBound are guaranteed to be KTypeImpl over SimpleType, as long as this function is only used from the bytecode
+    // generated by the compiler for `typeOf`.
+    return KTypeImpl(
+        KotlinTypeFactory.flexibleType(
+            (lowerBound as KTypeImpl).type as SimpleType,
+            (upperBound as KTypeImpl).type as SimpleType,
+        )
+    )
+}