Fix union related failures.

core/compiler.common/src/org/jetbrains/kotlin/types/model/TypeSystemContext.kt

@@ -136,7 +136,7 @@ interface TypeSystemCommonSuperTypesContext : TypeSystemContext, TypeSystemTypeF
 
     fun unionTypeAttributes(types: List<KotlinTypeMarker>): List<AnnotationMarker>
 
-    fun KotlinTypeMarker.replaceTypeAttributes(newAttributes: List<AnnotationMarker>): KotlinTypeMarker
+    fun KotlinTypeMarker.replaceCustomAttributes(newAttributes: List<AnnotationMarker>): KotlinTypeMarker
 }
 
 // This interface is only used to declare that implementing class is supposed to be used as a TypeSystemInferenceExtensionContext component

core/descriptors/src/org/jetbrains/kotlin/types/AnnotationsTypeAttribute.kt

@@ -10,9 +10,9 @@ import org.jetbrains.kotlin.descriptors.annotations.composeAnnotations
 import kotlin.reflect.KClass
 
 class AnnotationsTypeAttribute(val annotations: Annotations) : TypeAttribute<AnnotationsTypeAttribute>() {
-    override fun union(other: AnnotationsTypeAttribute?): AnnotationsTypeAttribute = this
+    override fun union(other: AnnotationsTypeAttribute?): AnnotationsTypeAttribute? = null
 
-    override fun intersect(other: AnnotationsTypeAttribute?): AnnotationsTypeAttribute = this
+    override fun intersect(other: AnnotationsTypeAttribute?): AnnotationsTypeAttribute? = null
 
     override fun add(other: AnnotationsTypeAttribute?): AnnotationsTypeAttribute {
         if (other == null) return this

core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt

@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.resolve.unsubstitutedUnderlyingType
 import org.jetbrains.kotlin.types.*
 import org.jetbrains.kotlin.types.model.*
 import org.jetbrains.kotlin.types.typeUtil.*
+import org.jetbrains.kotlin.utils.addIfNotNull
 import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 import org.jetbrains.kotlin.types.typeUtil.isSignedOrUnsignedNumberType as classicIsSignedOrUnsignedNumberType
@@ -644,12 +645,13 @@ interface ClassicTypeSystemContext : TypeSystemInferenceExtensionContext, TypeSy
         return (types as List<KotlinType>).map { it.unwrap().attributes }.reduce { x, y -> x.union(y) }.toList()
     }
 
-    override fun KotlinTypeMarker.replaceTypeAttributes(newAttributes: List<AnnotationMarker>): KotlinTypeMarker {
+    override fun KotlinTypeMarker.replaceCustomAttributes(newAttributes: List<AnnotationMarker>): KotlinTypeMarker {
         require(this is KotlinType)
-        if (newAttributes.isEmpty()) return this
         @Suppress("UNCHECKED_CAST")
+        val attributes = (newAttributes as List<TypeAttribute<*>>).filterNot { it is AnnotationsTypeAttribute }.toMutableList()
+        attributes.addIfNotNull(this.attributes.annotationsAttribute)
         return this.unwrap().replaceAttributes(
-            TypeAttributes.create(newAttributes as List<TypeAttribute<*>>)
+            TypeAttributes.create(attributes)
         )
     }