[Serialization] Workaround registering static writeSelf method in metadata

`IrGeneratedDeclarationsRegistrar` assumes that all generated functions
  are correct from a Kotlin point of view. But `writeSelf` method on JVM
  is a static method outside any object/companion object

So to properly calculate containing class for this method we should
  generate a dispatch receiver parameter, register the method in metadata,
  and then remove the parameter (to make function static)

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

@@ -15,8 +15,10 @@ import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.isSingleFieldValueClass
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.companionObject
+import org.jetbrains.kotlin.ir.util.copyTo
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.platform.jvm.isJvm
+import org.jetbrains.kotlin.resolve.annotations.JVM_STATIC_ANNOTATION_CLASS_ID
 import org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationPluginContext
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames
 import org.jetbrains.kotlinx.serialization.compiler.resolve.bitMaskSlotCount
@@ -58,17 +60,17 @@ class IrPreGenerator(
             modality = Modality.FINAL
             origin = SERIALIZATION_PLUGIN_ORIGIN
         }
-        method.apply {
-            dispatchReceiverParameter = null // function is static
-            excludeFromJsExport()
-        }
+        method.excludeFromJsExport()
 
-        val typeParams = irClass.typeParameters.map {
+        val typeParamsMap = irClass.typeParameters.associateWith {
             method.addTypeParameter(
                 it.name.asString(), compilerContext.irBuiltIns.anyNType
             )
         }
-        val typeParamsAsArguments = typeParams.map { it.defaultType }
+        // Despite this function should be static in bytecode, registerFunctionAsMetadataVisible needs a correct dispatch receiver
+        // to handle function metadata correctly. This dispatchReceiverParameter will become `null` later.
+        method.dispatchReceiverParameter = irClass.thisReceiver?.copyTo(method, remapTypeMap = typeParamsMap)
+        val typeParamsAsArguments = typeParamsMap.values.map { it.defaultType }
 
         // object
         method.addValueParameter(
@@ -96,7 +98,14 @@ class IrPreGenerator(
                 SERIALIZATION_PLUGIN_ORIGIN
             )
         }
+
+        compilerContext.referenceClass(JVM_STATIC_ANNOTATION_CLASS_ID)
+            ?.let { method.annotations += method.createAnnotationCallWithoutArgs(it) }
+
         compilerContext.metadataDeclarationRegistrar.registerFunctionAsMetadataVisible(method)
+
+        // Make function static in bytecode (see JvmStaticAnnotationLowering.makeStatic).
+        method.dispatchReceiverParameter = null
     }
 
     private fun preGenerateDeserializationConstructorIfNeeded() {

plugins/kotlinx-serialization/testData/boxIr/allConstructorsAccessible.kt

@@ -0,0 +1,19 @@
+// TARGET_BACKEND: JVM_IR
+// WITH_REFLECT
+
+import kotlinx.serialization.Serializable
+import kotlin.reflect.jvm.javaConstructor
+import kotlin.reflect.jvm.kotlinFunction
+
+@Serializable
+data class Tuple2<out A1, out A2>(
+    val _1: A1,
+    val _2: A2,
+)
+
+fun box(): String {
+    val cls = Tuple2::class
+    val ctor = cls.constructors.single { it.parameters.size == 4 }
+    val kf = ctor.javaConstructor?.kotlinFunction
+    return if (kf.toString() == "fun `<init>`(kotlin.Int, A1?, A2?, kotlinx.serialization.internal.SerializationConstructorMarker?): Tuple2<A1, A2>") "OK" else "Fail: $kf"
+}

plugins/kotlinx-serialization/tests-gen/org/jetbrains/kotlinx/serialization/runners/SerializationFirLightTreeBlackBoxTestGenerated.java

@@ -22,6 +22,12 @@ public class SerializationFirLightTreeBlackBoxTestGenerated extends AbstractSeri
     @TestMetadata("plugins/kotlinx-serialization/testData/boxIr")
     @TestDataPath("$PROJECT_ROOT")
     public class BoxIr {
+        @Test
+        @TestMetadata("allConstructorsAccessible.kt")
+        public void testAllConstructorsAccessible() throws Exception {
+            runTest("plugins/kotlinx-serialization/testData/boxIr/allConstructorsAccessible.kt");
+        }
+
         @Test
         public void testAllFilesPresentInBoxIr() throws Exception {
             KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("plugins/kotlinx-serialization/testData/boxIr"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM_IR, true);

plugins/kotlinx-serialization/tests-gen/org/jetbrains/kotlinx/serialization/runners/SerializationIrBoxTestGenerated.java

@@ -20,6 +20,12 @@ import java.util.regex.Pattern;
 @TestMetadata("plugins/kotlinx-serialization/testData/boxIr")
 @TestDataPath("$PROJECT_ROOT")
 public class SerializationIrBoxTestGenerated extends AbstractSerializationIrBoxTest {
+    @Test
+    @TestMetadata("allConstructorsAccessible.kt")
+    public void testAllConstructorsAccessible() throws Exception {
+        runTest("plugins/kotlinx-serialization/testData/boxIr/allConstructorsAccessible.kt");
+    }
+
     @Test
     public void testAllFilesPresentInBoxIr() throws Exception {
         KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("plugins/kotlinx-serialization/testData/boxIr"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM_IR, true);