[K/N] Make cast to objc forward declaration unchecked

Before this commit it caused compiler crash.
Unchecked cast warning to be done later.

^KT-59645

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ObjCInterop.kt

@@ -67,6 +67,10 @@ fun IrClass.isExternalObjCClass(): Boolean = this.isObjCClass() &&
 fun ClassDescriptor.isObjCForwardDeclaration(): Boolean =
         this.findPackage().fqName.startsWith(objcnamesForwardDeclarationsPackageName)
 
+fun IrClass.isObjCForwardDeclaration(): Boolean =
+        getPackageFragment().packageFqName.startsWith(objcnamesForwardDeclarationsPackageName)
+
+
 fun ClassDescriptor.isObjCMetaClass(): Boolean = this.getAllSuperClassifiers().any {
     it.fqNameSafe == objCClassFqName
 }

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/TypeOperatorLowering.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.backend.konan.lower
 import org.jetbrains.kotlin.backend.common.CommonBackendContext
 import org.jetbrains.kotlin.backend.common.FileLoweringPass
 import org.jetbrains.kotlin.backend.common.lower.*
+import org.jetbrains.kotlin.backend.konan.isObjCForwardDeclaration
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.expressions.IrExpression
@@ -52,9 +53,18 @@ internal class TypeOperatorLowering(val context: CommonBackendContext) : FileLow
         irFile.transformChildren(this, null)
     }
 
+    private fun effectiveCheckType(type: IrType) : IrType {
+        val erasedType = type.erasure()
+        return if (erasedType.classOrNull?.owner?.isObjCForwardDeclaration() == true) {
+            context.irBuiltIns.anyType.mergeNullability(erasedType)
+        } else {
+            erasedType
+        }
+    }
+
     private fun lowerCast(expression: IrTypeOperatorCall): IrExpression {
         builder.at(expression)
-        val typeOperand = expression.typeOperand.erasure()
+        val typeOperand = effectiveCheckType(expression.typeOperand)
         return if (typeOperand == expression.typeOperand) {
             expression
         } else {
@@ -63,7 +73,7 @@ internal class TypeOperatorLowering(val context: CommonBackendContext) : FileLow
     }
 
     private fun lowerSafeCast(expression: IrTypeOperatorCall): IrExpression {
-        val typeOperand = expression.typeOperand.erasure()
+        val typeOperand = effectiveCheckType(expression.typeOperand)
 
         return builder.irBlock(expression) {
             +irLetS(expression.argument) { variable ->

kotlin-native/backend.native/tests/build.gradle

@@ -4023,6 +4023,16 @@ createInterop("cForwardDeclarationsTwoLibs2") {
 }
 
 if (PlatformInfo.isAppleTarget(project)) {
+    createInterop("forwardDeclarationsCastA") {
+        it.defFile "interop/forwardDeclarationsCast/a.def"
+    }
+
+    createInterop("forwardDeclarationsCastB") {
+        it.defFile "interop/forwardDeclarationsCast/b.def"
+        it.headers "$projectDir/interop/forwardDeclarationsCast/b.h"
+        it.extraOpts "-Xcompile-source", "$projectDir/interop/forwardDeclarationsCast/b.m"
+    }
+
     createInterop("objcSmoke") {
         it.defFile 'interop/objc/objcSmoke.def'
         it.headers "$projectDir/interop/objc/smoke.h"
@@ -4155,7 +4165,7 @@ createInterop("exceptions_cCallback") {
 /**
  * Creates a task for the interop test. Configures runner and adds library and test build tasks.
  */
-Task interopTestBase(String name, boolean multiFile, Closure<KonanInteropTest> configureClosure) {
+Task interopTestBase(String name, boolean multiFile, boolean interop2ForMainOnly, Closure<KonanInteropTest> configureClosure) {
     return KotlinNativeTestKt.createTest(project, name, KonanInteropTest) { task ->
         task.configure(configureClosure)
         if (task.enabled) {
@@ -4173,7 +4183,7 @@ Task interopTestBase(String name, boolean multiFile, Closure<KonanInteropTest> c
                     library(lib, targets: [targetName]) {
                         libraries {
                             artifact interopLib
-                            if (interopLib2 != null) artifact interopLib2
+                            if (interopLib2 != null && !interop2ForMainOnly) artifact interopLib2
                         }
                         srcFiles task.lib
                         baseDir  "$testOutputLocal/$name"
@@ -4202,11 +4212,11 @@ Task interopTestBase(String name, boolean multiFile, Closure<KonanInteropTest> c
 }
 
 Task interopTest(String name, Closure<KonanInteropTest> configureClosure) {
-    return interopTestBase(name, false, configureClosure)
+    return interopTestBase(name, false, false, configureClosure)
 }
 
 Task interopTestMultifile(String name, Closure<KonanInteropTest> configureClosure) {
-    return interopTestBase(name, true, configureClosure)
+    return interopTestBase(name, true, false, configureClosure)
 }
 
 standaloneTest("interop_objc_allocException") {
@@ -4447,6 +4457,14 @@ interopTest("interop_kt51925") {
     useGoldenData = true
 }
 
+interopTestBase("interop_forwardDeclarationsCast", false, true) {
+    enabled = isAppleTarget(project)
+    interop = 'forwardDeclarationsCastA'
+    interop2 = 'forwardDeclarationsCastB'
+    lib = 'interop/forwardDeclarationsCast/lib.kt'
+    source = 'interop/forwardDeclarationsCast/main.kt'
+}
+
 dynamicTest("interop_kt43502") {
     interop = "kt43502"
     source = "interop/kt43502/main.kt"

kotlin-native/backend.native/tests/interop/forwardDeclarationsCast/a.def

@@ -0,0 +1,18 @@
+language = Objective-C
+---
+#import <Foundation/Foundation.h>
+#include <stdio.h>
+
+struct ForwardDeclaredStruct;
+@class ForwardDeclaredClass;
+@protocol ForwardDeclaredProtocol;
+
+NSString* consumeProtocol(id<ForwardDeclaredProtocol> s) {
+	return [NSString stringWithUTF8String:"Protocol"];
+}
+NSString* consumeClass(ForwardDeclaredClass* s) {
+	return [NSString stringWithUTF8String:"Class"];
+}
+NSString* consumeStruct(struct ForwardDeclaredStruct* s) {
+	return [NSString stringWithUTF8String:"Struct"];
+}

kotlin-native/backend.native/tests/interop/forwardDeclarationsCast/b.def

@@ -0,0 +1,2 @@
+language = Objective-C
+---

kotlin-native/backend.native/tests/interop/forwardDeclarationsCast/b.h

@@ -0,0 +1,18 @@
+#define NS_FORMAT_ARGUMENT(X)
+#import <Foundation/Foundation.h>
+
+@protocol ForwardDeclaredProtocol
+@end
+
+@interface ForwardDeclaredProtocolImpl : NSObject<ForwardDeclaredProtocol>
+@end;
+
+
+@interface ForwardDeclaredClass : NSObject
+@end;
+
+struct ForwardDeclaredStruct {};
+
+id<ForwardDeclaredProtocol> produceProtocol();
+ForwardDeclaredClass* produceClass();
+struct ForwardDeclaredStruct* produceStruct();

kotlin-native/backend.native/tests/interop/forwardDeclarationsCast/b.m

@@ -0,0 +1,21 @@
+#import "b.h"
+
+@implementation ForwardDeclaredProtocolImpl : NSObject
+@end;
+
+@implementation ForwardDeclaredClass : NSObject
+@end;
+
+id<ForwardDeclaredProtocol> produceProtocol() {
+  return [ForwardDeclaredProtocolImpl new];
+}
+
+ForwardDeclaredClass* produceClass() {
+  return [ForwardDeclaredClass new];
+}
+
+struct ForwardDeclaredStruct S;
+
+struct ForwardDeclaredStruct* produceStruct() {
+  return &S;
+}

kotlin-native/backend.native/tests/interop/forwardDeclarationsCast/lib.kt

@@ -0,0 +1,18 @@
+@file:OptIn(kotlinx.cinterop.ExperimentalForeignApi::class)
+
+import cnames.structs.ForwardDeclaredStruct
+import objcnames.classes.ForwardDeclaredClass
+import objcnames.protocols.ForwardDeclaredProtocolProtocol
+import a.*
+import kotlinx.cinterop.*
+
+fun testStruct(s: Any?) = consumeStruct(s as CPointer<ForwardDeclaredStruct>)
+fun testClass(s: Any?) = consumeClass(s as ForwardDeclaredClass)
+fun testProtocol(s: Any?) = consumeProtocol(s as ForwardDeclaredProtocolProtocol)
+
+
+fun <T : ForwardDeclaredClass> testClass2Impl(s: Any?) = consumeClass(s as T)
+fun <T : ForwardDeclaredProtocolProtocol> testProtocol2Impl(s: Any?) = consumeProtocol(s as T)
+
+fun testClass2(s: Any?) = testClass2Impl<ForwardDeclaredClass>(s)
+fun testProtocol2(s: Any?) = testProtocol2Impl<ForwardDeclaredProtocolProtocol>(s)

kotlin-native/backend.native/tests/interop/forwardDeclarationsCast/main.kt

@@ -0,0 +1,13 @@
+@file:OptIn(kotlinx.cinterop.ExperimentalForeignApi::class)
+
+import a.*
+import b.*
+
+
+fun main() {
+	if (testStruct(produceStruct()) != "Struct") throw IllegalStateException()
+	if (testClass(produceClass()) != "Class") throw IllegalStateException()
+    if (testProtocol(produceProtocol()) != "Protocol") throw IllegalStateException()
+	if (testClass2(produceClass()) != "Class") throw IllegalStateException()
+	if (testProtocol2(produceProtocol()) != "Protocol") throw IllegalStateException()
+}