Fix typealias usage nullability and annotations lost in deserialization

Issue #KT-40824 Fixed

compiler/testData/compileKotlinAgainstKotlin/annotationOnTypeUseInTypeAlias.kt

@@ -0,0 +1,37 @@
+// TARGET_BACKEND: JVM
+// WITH_REFLECT
+// FILE: A.kt
+@Target(AnnotationTarget.TYPE)
+annotation class Anno(val value: String)
+
+class Foo
+
+typealias MyFoo = Foo
+typealias MyMaybeFoo = Foo?
+
+class C<T>(val t: T)
+
+typealias MyCMyFoo = C<@Anno("OK") MyFoo?>
+typealias MyCMaybeFoo = C<@Anno("OK") MyMaybeFoo>
+
+// FILE: B.kt
+fun testMyFoo(myc: MyCMyFoo) {}
+fun testMyMaybeFoo(mycmyb: MyCMaybeFoo) {}
+
+fun box(): String {
+    testMyFoo(C(null))
+    testMyMaybeFoo(C(null))
+
+    for (fn in listOf(::testMyFoo, ::testMyMaybeFoo)) {
+        val mycType = fn.parameters.single().type
+        val argumentType = mycType.arguments.single().type!!
+        if (!argumentType.isMarkedNullable)
+            return "Fail on $fn: argument type should be seen as nullable"
+
+        val annotations = argumentType.annotations
+        if (annotations.toString() != "[@Anno(value=OK)]")
+            return "Fail on $fn: $annotations"
+    }
+
+    return "OK"
+}

compiler/tests/org/jetbrains/kotlin/codegen/CompileKotlinAgainstKotlinTestGenerated.java

@@ -38,6 +38,11 @@ public class CompileKotlinAgainstKotlinTestGenerated extends AbstractCompileKotl
         runTest("compiler/testData/compileKotlinAgainstKotlin/annotationInInterface.kt");
     }
 
+    @TestMetadata("annotationOnTypeUseInTypeAlias.kt")
+    public void testAnnotationOnTypeUseInTypeAlias() throws Exception {
+        runTest("compiler/testData/compileKotlinAgainstKotlin/annotationOnTypeUseInTypeAlias.kt");
+    }
+
     @TestMetadata("annotationsOnTypeAliases.kt")
     public void testAnnotationsOnTypeAliases() throws Exception {
         runTest("compiler/testData/compileKotlinAgainstKotlin/annotationsOnTypeAliases.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrCompileKotlinAgainstKotlinTestGenerated.java

@@ -38,6 +38,11 @@ public class IrCompileKotlinAgainstKotlinTestGenerated extends AbstractIrCompile
         runTest("compiler/testData/compileKotlinAgainstKotlin/annotationInInterface.kt");
     }
 
+    @TestMetadata("annotationOnTypeUseInTypeAlias.kt")
+    public void testAnnotationOnTypeUseInTypeAlias() throws Exception {
+        runTest("compiler/testData/compileKotlinAgainstKotlin/annotationOnTypeUseInTypeAlias.kt");
+    }
+
     @TestMetadata("annotationsOnTypeAliases.kt")
     public void testAnnotationsOnTypeAliases() throws Exception {
         runTest("compiler/testData/compileKotlinAgainstKotlin/annotationsOnTypeAliases.kt");

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/TypeDeserializer.kt

@@ -92,8 +92,12 @@ class TypeDeserializer(
         val declarationDescriptor = constructor.declarationDescriptor
 
         val simpleType = when {
-            expandTypeAliases && declarationDescriptor is TypeAliasDescriptor ->
+            expandTypeAliases && declarationDescriptor is TypeAliasDescriptor -> {
-                with(KotlinTypeFactory) { declarationDescriptor.computeExpandedType(arguments) }
+                val expandedType = with(KotlinTypeFactory) { declarationDescriptor.computeExpandedType(arguments) }
+                expandedType
+                    .makeNullableAsSpecified(expandedType.isNullable() || proto.nullable)
+                    .replaceAnnotations(Annotations.create(annotations + expandedType.annotations))
+            }
             Flags.SUSPEND_TYPE.get(proto.flags) ->
                 createSuspendFunctionType(annotations, constructor, arguments, proto.nullable)
             else ->