From 161fe1d2ca9fad5f2222963e5615c9848c90db3a Mon Sep 17 00:00:00 2001
From: Dmitriy Dolovov <Dmitriy.Dolovov@jetbrains.com>
Date: Thu, 25 May 2023 11:19:43 +0200
Subject: [PATCH] [IR] Don't produce gaps for skipped IR declarations during
 serialization

---
 .../common/serialization/IrFileSerializer.kt  |  7 +++----
 .../kotlin/library/KotlinLibraryWriter.kt     | 20 ++-----------------
 2 files changed, 5 insertions(+), 22 deletions(-)

diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
index e15833fa52d..0f58e4d983c 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
@@ -21,8 +21,6 @@ import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
 import org.jetbrains.kotlin.library.SerializedDeclaration
 import org.jetbrains.kotlin.library.SerializedIrFile
-import org.jetbrains.kotlin.library.SkippedDeclaration
-import org.jetbrains.kotlin.library.TopLevelDeclaration
 import org.jetbrains.kotlin.library.impl.IrMemoryArrayWriter
 import org.jetbrains.kotlin.library.impl.IrMemoryDeclarationWriter
 import org.jetbrains.kotlin.library.impl.IrMemoryStringWriter
@@ -1425,7 +1423,8 @@ open class IrFileSerializer(
 
         file.declarations.forEach {
             if (skipExpects && it.descriptor.isExpectMember && !it.descriptor.isSerializableExpectClass) {
-                topLevelDeclarations.add(SkippedDeclaration)
+                // Skip the declaration unless it is `expect annotation class` marked with `OptionalExpectation`
+                // without the corresponding `actual` counterpart for the current leaf target.
                 return@forEach
             }
 
@@ -1437,7 +1436,7 @@ open class IrFileSerializer(
             // TODO: keep order similar
             val sigIndex = protoIdSignatureMap[idSig]
                 ?: if (it is IrErrorDeclaration) protoIdSignature(idSig) else error("Not found ID for $idSig (${it.render()})")
-            topLevelDeclarations.add(TopLevelDeclaration(sigIndex, idSig.toString(), byteArray))
+            topLevelDeclarations.add(SerializedDeclaration(sigIndex, idSig.toString(), byteArray))
             proto.addDeclarationId(sigIndex)
         }
 
diff --git a/compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinLibraryWriter.kt b/compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinLibraryWriter.kt
index 94daf7195d1..69be5f488ea 100644
--- a/compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinLibraryWriter.kt
+++ b/compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinLibraryWriter.kt
@@ -32,24 +32,8 @@ class SerializedMetadata(
     val fragmentNames: List<String>
 )
 
-sealed class SerializedDeclaration {
-    abstract val id: Int
-    abstract val size: Int
-    abstract val bytes: ByteArray
-
-    abstract val declarationName: String
-}
-
-class TopLevelDeclaration(override val id: Int, override val declarationName: String, override val bytes: ByteArray) :
-    SerializedDeclaration() {
-    override val size = bytes.size
-}
-
-object SkippedDeclaration : SerializedDeclaration() {
-    override val id = -1
-    override val size = 0
-    override val bytes = ByteArray(0)
-    override val declarationName: String = "<SKIPPED>"
+class SerializedDeclaration(val id: Int, val declarationName: String, val bytes: ByteArray) {
+    val size = bytes.size
 }
 
 class SerializedIrFile(