Make visibilities of writeSelf and deserialization constructor in FIR

same as they were in K1 (see KSerializerDescriptorResolver): internal for
final classes and public for non-final.

Unfortunately, there are no Klib API dumps tests in the compiler, so I tested manually.

#KT-64124 Fixed

plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/IrPreGenerator.kt

@@ -56,7 +56,7 @@ class IrPreGenerator(
         val method = irClass.addFunction {
             name = SerialEntityNames.WRITE_SELF_NAME
             returnType = compilerContext.irBuiltIns.unitType
-            visibility = DescriptorVisibilities.PUBLIC
+            visibility = if (irClass.modality == Modality.FINAL) DescriptorVisibilities.INTERNAL else DescriptorVisibilities.PUBLIC
             modality = Modality.FINAL
             origin = SERIALIZATION_PLUGIN_ORIGIN
         }
@@ -118,7 +118,7 @@ class IrPreGenerator(
         if (irClass.findSerializableSyntheticConstructor() != null) return
         val ctor = irClass.addConstructor {
             origin = SERIALIZATION_PLUGIN_ORIGIN
-            visibility = DescriptorVisibilities.PUBLIC
+            visibility = if (irClass.modality == Modality.FINAL) DescriptorVisibilities.INTERNAL else DescriptorVisibilities.PUBLIC
         }.apply { excludeFromJsExport() }
         val markerClassSymbol =
             compilerContext.getClassFromInternalSerializationPackage(SerialEntityNames.SERIAL_CTOR_MARKER_NAME.asString())

plugins/kotlinx-serialization/testData/codegen/Basic.asm.fir.txt

@@ -176,7 +176,7 @@ public final class ListOfUsers$$serializer : java/lang/Object, kotlinx/serializa
           ALOAD (2)
           ALOAD (4)
           ALOAD (3)
-          INVOKESTATIC (ListOfUsers, write$Self, (LListOfUsers;Lkotlinx/serialization/encoding/CompositeEncoder;Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
+          INVOKESTATIC (ListOfUsers, write$Self$main, (LListOfUsers;Lkotlinx/serialization/encoding/CompositeEncoder;Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
           ALOAD (4)
           ALOAD (3)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, endStructure, (Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
@@ -290,7 +290,7 @@ public final class ListOfUsers : java/lang/Object {
 
     public final java.util.List getList()
 
-    public final static void write$Self(ListOfUsers self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
+    public final static void write$Self$main(ListOfUsers self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
         LINENUMBER (12)
           GETSTATIC (ListOfUsers, $childSerializers, [Lkotlinx/serialization/KSerializer;)
@@ -478,7 +478,7 @@ public final class OptionalUser$$serializer : java/lang/Object, kotlinx/serializ
           ALOAD (2)
           ALOAD (4)
           ALOAD (3)
-          INVOKESTATIC (OptionalUser, write$Self, (LOptionalUser;Lkotlinx/serialization/encoding/CompositeEncoder;Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
+          INVOKESTATIC (OptionalUser, write$Self$main, (LOptionalUser;Lkotlinx/serialization/encoding/CompositeEncoder;Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
           ALOAD (4)
           ALOAD (3)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, endStructure, (Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
@@ -623,7 +623,7 @@ public final class OptionalUser : java/lang/Object {
 
     public final User getUser()
 
-    public final static void write$Self(OptionalUser self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
+    public final static void write$Self$main(OptionalUser self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
         LINENUMBER (9)
           ALOAD (1)
@@ -859,7 +859,7 @@ public final class User$$serializer : java/lang/Object, kotlinx/serialization/in
           ALOAD (2)
           ALOAD (4)
           ALOAD (3)
-          INVOKESTATIC (User, write$Self, (LUser;Lkotlinx/serialization/encoding/CompositeEncoder;Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
+          INVOKESTATIC (User, write$Self$main, (LUser;Lkotlinx/serialization/encoding/CompositeEncoder;Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
           ALOAD (4)
           ALOAD (3)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, endStructure, (Lkotlinx/serialization/descriptors/SerialDescriptor;)V)
@@ -969,7 +969,7 @@ public final class User : java/lang/Object {
 
     public final java.lang.String getLastName()
 
-    public final static void write$Self(User self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
+    public final static void write$Self$main(User self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
         LINENUMBER (6)
           ALOAD (1)

plugins/kotlinx-serialization/testData/codegen/Intrinsics.asm.fir.txt

@@ -59,7 +59,7 @@ public final class Box : java/lang/Object {
 
     public java.lang.String toString()
 
-    public final static void write$Self(Box self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc, kotlinx.serialization.KSerializer typeSerial0)
+    public final static void write$Self$main(Box self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc, kotlinx.serialization.KSerializer typeSerial0)
 }
 
 public final class IntrinsicsKt : java/lang/Object {
@@ -263,5 +263,5 @@ public final class Simple : java/lang/Object {
 
     public final java.lang.String getLastName()
 
-    public final static void write$Self(Simple self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc)
+    public final static void write$Self$main(Simple self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc)
 }

plugins/kotlinx-serialization/testData/codegen/IntrinsicsAdvanced.asm.fir.txt

@@ -205,5 +205,5 @@ public final class Simple : java/lang/Object {
 
     public final java.lang.String getLastName()
 
-    public final static void write$Self(Simple self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc)
+    public final static void write$Self$main(Simple self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc)
 }

plugins/kotlinx-serialization/testData/codegen/Sealed.asm.fir.txt

@@ -256,7 +256,7 @@ public final class Container : java/lang/Object {
 
     public final Result getR()
 
-    public final static void write$Self(Container self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
+    public final static void write$Self$main(Container self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
         LINENUMBER (18)
           GETSTATIC (Container, $childSerializers, [Lkotlinx/serialization/KSerializer;)
@@ -696,7 +696,7 @@ public final class Result$OK : Result {
 
     public final java.lang.String getS()
 
-    public final static void write$Self(Result$OK self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
+    public final static void write$Self$main(Result$OK self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
         LINENUMBER (14)
           ALOAD (0)