[klib] Don't deserialize the list of sealed subclasses from klibs

tl;dr the current design of klibs does not allow to properly deserialize
the list of sealed subclasses in a sound way. It is possible that
a subclass of a sealed class is declared in a different file, AND is
private in that file.

A more detailed explanation:

Right now we don't serialize file signatures at all.
However, a private declaration's signature must necessarily include
the file signature.

How do we serialize a private declaration's signature into a klib
and deserialize it later?

**Serialization** is simple: we just serialize the file signature as
an empty protobuf message.

When we are **deserializing** a private declaration, we look at the file
that is being deserialized right now, and construct the file signature
based on that.

This logic, however, doesn't always work. An example is KT-54028.

Basically, if we have a sealed interface with a private implementor
declared in a different file, this breaks:

1. We are deserializing the sealed interface. The deserializer knows
that we are now in the file in which the sealed interface is declared.
2. As part of deserializing the interface, we deserialize its sealed
subclasses.
3. Naturally, we come to deserializing the private implementor that is
declared in another file, but the deserializer still thinks that we are
in the file in which the interface is declared. A wrong signature is
created, which leads to linkage failure.

We *could* fix this by properly serializing the file signature,
i.e. instead of an empty protobuf message we could write the file path
and its package to the klib. However, there a problems with this
approach:

- The current design of signatures allows a situation where two
different files can have the same relative path
(for example, with the help of the `-Xklib-relative-path-base` compiler
flag) *and* the same package, which would introduce ambiguity during
linkage.
- Most importantly, this appoach won't work well with incremental
compilation of klibs. Currently we rely on the assumption that all
cross-file references are handled with public signatures, and private
signatures are only used inside a single file. This allows to move
declarations across files without recompiling it's use sites.

It has been decided to apply the following hacky solution: we just don't
deserialize the list of sealed subclasses from klibs.
The list of sealed subclasses is not used in lowerings, so it should be
safe.

#KT-54028 Fixed

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirLightTreeBlackBoxCodegenTestGenerated.java

@@ -48799,6 +48799,18 @@ public class FirLightTreeBlackBoxCodegenTestGenerated extends AbstractFirLightTr
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirPsiBlackBoxCodegenTestGenerated.java

@@ -48799,6 +48799,18 @@ public class FirPsiBlackBoxCodegenTestGenerated extends AbstractFirPsiBlackBoxCo
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

compiler/ir/ir.tree/gen/org/jetbrains/kotlin/ir/declarations/IrClass.kt

@@ -59,6 +59,14 @@ abstract class IrClass : IrDeclarationBase(), IrPossiblyExternalDeclaration,
 
     abstract var valueClassRepresentation: ValueClassRepresentation<IrSimpleType>?
 
+    /**
+     * If this is a sealed class or interface, this list contains symbols of all its immediate
+     * subclasses.
+     * Otherwise, this is an empty list.
+     *
+     * NOTE: If this [IrClass] was deserialized from a klib, this list will always be empty!
+     * See [KT-54028](https://youtrack.jetbrains.com/issue/KT-54028).
+     */
     abstract var sealedSubclasses: List<IrClassSymbol>
 
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =

compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/IrTree.kt

@@ -199,7 +199,15 @@ object IrTree : AbstractTreeBuilder() {
             type<ValueClassRepresentation<*>>().withArgs(type(Packages.types, "IrSimpleType")),
             nullable = true,
         )
-        +listField("sealedSubclasses", classSymbolType, mutability = Var)
+        +listField("sealedSubclasses", classSymbolType, mutability = Var) {
+            kdoc = """
+            If this is a sealed class or interface, this list contains symbols of all its immediate subclasses.
+            Otherwise, this is an empty list.
+            
+            NOTE: If this [${elementName2typeName(this@element.name)}] was deserialized from a klib, this list will always be empty!
+            See [KT-54028](https://youtrack.jetbrains.com/issue/KT-54028).
+            """.trimIndent()
+        }
     }
     val attributeContainer: ElementConfig by element(Declaration) {
         kDoc = """

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeclarationDeserializer.kt

@@ -389,7 +389,8 @@ class IrDeclarationDeserializer(
                     else -> computeMissingInlineClassRepresentationForCompatibility(this)
                 }
 
-                sealedSubclasses = proto.sealedSubclassList.map { deserializeIrSymbol(it).checkSymbolType(CLASS_SYMBOL) }
+                // It has been desided not to deserialize the list of sealed subclasses because of KT-54028
+                // sealedSubclasses = proto.sealedSubclassList.map { deserializeIrSymbol(it).checkSymbolType(CLASS_SYMBOL) }
 
                 fakeOverrideBuilder.enqueueClass(this, signature, compatibilityMode)
             }

compiler/testData/codegen/box/sealed/kt54028.kt

@@ -0,0 +1,27 @@
+// KT-54028
+
+// MODULE: lib
+// FILE: file1.kt
+
+sealed interface LazyGridLayoutInfo {
+    fun ok(): String
+}
+
+// FILE: file2.kt
+
+class LazyGridState {
+    val layoutInfo: LazyGridLayoutInfo
+        get() = EmptyLazyGridLayoutInfo
+}
+
+private object EmptyLazyGridLayoutInfo : LazyGridLayoutInfo {
+    override fun ok() = "OK"
+}
+
+// MODULE: main(lib)
+// FILE: main.kt
+
+fun box(): String {
+    return LazyGridState().layoutInfo.ok()
+}
+

compiler/testData/codegen/box/sealed/kt54028_cursed.kt

@@ -0,0 +1,37 @@
+// ALLOW_FILES_WITH_SAME_NAMES
+
+// The test infrastructure for Kotlin/Native doesn't allow files with same names.
+// IGNORE_BACKEND: NATIVE
+
+// IGNORE_BACKEND: JS
+// IGNORE_BACKEND: WASM
+// IGNORE_BACKEND_K2: JS_IR
+
+// Test that if we have two different files with the same name in the same package, KT-54028 doesn't reproduce.
+
+// MODULE: lib
+
+// FILE: cursed.kt
+
+sealed interface LazyGridLayoutInfo {
+    fun ok(): String
+}
+
+// FILE: cursed.kt
+
+class LazyGridState {
+    val layoutInfo: LazyGridLayoutInfo
+        get() = EmptyLazyGridLayoutInfo
+}
+
+private object EmptyLazyGridLayoutInfo : LazyGridLayoutInfo {
+    override fun ok() = "OK"
+}
+
+// MODULE: main(lib)
+// FILE: main.kt
+
+fun box(): String {
+    return LazyGridState().layoutInfo.ok()
+}
+

compiler/testData/ir/irText/classes/sealedClasses.kt

@@ -1,6 +1,7 @@
 // FIR_IDENTICAL
+// SKIP_KLIB_TEST
 sealed class Expr {
     class Const(val number: Double) : Expr()
     class Sum(val e1: Expr, val e2: Expr) : Expr()
     object NotANumber : Expr()
-}
+}

compiler/testData/ir/irText/declarations/multiplatform/expectedSealedClass.kt

@@ -2,6 +2,7 @@
 // IGNORE_BACKEND_K2: JS_IR
 // IGNORE_BACKEND_K2: JS_IR_ES6
 // !LANGUAGE: +MultiPlatformProjects
+// SKIP_KLIB_TEST
 
 expect sealed class Ops()
 expect class Add() : Ops

compiler/testData/ir/irText/firProblems/ArrayMap.kt

@@ -1,4 +1,5 @@
 // WITH_STDLIB
+// SKIP_KLIB_TEST
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java

@@ -46309,6 +46309,18 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -48799,6 +48799,18 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenWithIrInlinerTestGenerated.java

@@ -48799,6 +48799,18 @@ public class IrBlackBoxCodegenWithIrInlinerTestGenerated extends AbstractIrBlack
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -37475,6 +37475,16 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {
             runTest("compiler/testData/codegen/box/sealed/multipleFiles_enabled.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/JsCodegenBoxTestGenerated.java

@@ -34365,6 +34365,18 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirJsCodegenBoxTestGenerated.java

@@ -34677,6 +34677,18 @@ public class FirJsCodegenBoxTestGenerated extends AbstractFirJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrJsCodegenBoxTestGenerated.java

@@ -34677,6 +34677,18 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrJsES6CodegenBoxTestGenerated.java

@@ -34677,6 +34677,18 @@ public class IrJsES6CodegenBoxTestGenerated extends AbstractIrJsES6CodegenBoxTes
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @Test
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @Test
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @Test
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/blackboxtest/FirNativeCodegenBoxTestGenerated.java

@@ -38735,6 +38735,18 @@ public class FirNativeCodegenBoxTestGenerated extends AbstractNativeCodegenBoxTe
                 runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
             }
 
+            @Test
+            @TestMetadata("kt54028.kt")
+            public void testKt54028() throws Exception {
+                runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+            }
+
+            @Test
+            @TestMetadata("kt54028_cursed.kt")
+            public void testKt54028_cursed() throws Exception {
+                runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+            }
+
             @Test
             @TestMetadata("multipleFiles_enabled.kt")
             public void testMultipleFiles_enabled() throws Exception {

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/blackboxtest/FirNativeCodegenBoxTestNoPLGenerated.java

@@ -39693,6 +39693,18 @@ public class FirNativeCodegenBoxTestNoPLGenerated extends AbstractNativeCodegenB
                 runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
             }
 
+            @Test
+            @TestMetadata("kt54028.kt")
+            public void testKt54028() throws Exception {
+                runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+            }
+
+            @Test
+            @TestMetadata("kt54028_cursed.kt")
+            public void testKt54028_cursed() throws Exception {
+                runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+            }
+
             @Test
             @TestMetadata("multipleFiles_enabled.kt")
             public void testMultipleFiles_enabled() throws Exception {

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/blackboxtest/NativeCodegenBoxTestGenerated.java

@@ -38256,6 +38256,18 @@ public class NativeCodegenBoxTestGenerated extends AbstractNativeCodegenBoxTest
                 runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
             }
 
+            @Test
+            @TestMetadata("kt54028.kt")
+            public void testKt54028() throws Exception {
+                runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+            }
+
+            @Test
+            @TestMetadata("kt54028_cursed.kt")
+            public void testKt54028_cursed() throws Exception {
+                runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+            }
+
             @Test
             @TestMetadata("multipleFiles_enabled.kt")
             public void testMultipleFiles_enabled() throws Exception {

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/blackboxtest/NativeCodegenBoxTestNoPLGenerated.java

@@ -39214,6 +39214,18 @@ public class NativeCodegenBoxTestNoPLGenerated extends AbstractNativeCodegenBoxT
                 runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
             }
 
+            @Test
+            @TestMetadata("kt54028.kt")
+            public void testKt54028() throws Exception {
+                runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+            }
+
+            @Test
+            @TestMetadata("kt54028_cursed.kt")
+            public void testKt54028_cursed() throws Exception {
+                runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+            }
+
             @Test
             @TestMetadata("multipleFiles_enabled.kt")
             public void testMultipleFiles_enabled() throws Exception {

wasm/wasm.tests/tests-gen/org/jetbrains/kotlin/wasm/test/IrCodegenBoxWasmTestGenerated.java

@@ -30990,6 +30990,16 @@ public class IrCodegenBoxWasmTestGenerated extends AbstractIrCodegenBoxWasmTest
             runTest("compiler/testData/codegen/box/sealed/kt49752.kt");
         }
 
+        @TestMetadata("kt54028.kt")
+        public void testKt54028() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028.kt");
+        }
+
+        @TestMetadata("kt54028_cursed.kt")
+        public void testKt54028_cursed() throws Exception {
+            runTest("compiler/testData/codegen/box/sealed/kt54028_cursed.kt");
+        }
+
         @TestMetadata("multipleFiles_enabled.kt")
         public void testMultipleFiles_enabled() throws Exception {
             runTest("compiler/testData/codegen/box/sealed/multipleFiles_enabled.kt");