Native: add KotlinThrowable.asError() to the generated Obj-C framework

This method can be useful when overriding a throwing Kotlin method in
Swift or Obj-C. In this case, a user can call asError to wrap Kotlin exception
to (NS)Error and then throw it to Kotlin, which will unwrap it back.

^KT-45127 Fixed

core/descriptors/src/org/jetbrains/kotlin/builtins/KotlinBuiltIns.java

@@ -961,6 +961,10 @@ public abstract class KotlinBuiltIns {
         return isConstructedFromGivenClass(type, FqNames.throwable);
     }
 
+    public static boolean isThrowable(@NotNull ClassDescriptor descriptor) {
+        return classFqNameEquals(descriptor, FqNames.throwable.toUnsafe());
+    }
+
     public static boolean isKClass(@NotNull ClassDescriptor descriptor) {
         return classFqNameEquals(descriptor, FqNames.kClass);
     }

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

@@ -497,6 +497,7 @@ internal class Llvm(val context: Context, val llvmModule: LLVMModuleRef) {
     val Kotlin_ObjCExport_GetAssociatedObject by lazyRtFunction
     val Kotlin_ObjCExport_AbstractMethodCalled by lazyRtFunction
     val Kotlin_ObjCExport_RethrowExceptionAsNSError by lazyRtFunction
+    val Kotlin_ObjCExport_WrapExceptionToNSError by lazyRtFunction
     val Kotlin_ObjCExport_RethrowNSErrorAsException by lazyRtFunction
     val Kotlin_ObjCExport_AllocInstanceWithAssociatedObject by lazyRtFunction
     val Kotlin_ObjCExport_createContinuationArgument by lazyRtFunction

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/objcexport/ObjCExportCodeGenerator.kt

@@ -1291,6 +1291,9 @@ private fun ObjCExportCodeGenerator.createTypeAdapter(
                     createObjectInstanceAdapter(irClass, it.selector)
                 }
             }
+            ObjCKotlinThrowableAsErrorMethod -> {
+                adapters += createThrowableAsErrorAdapter()
+            }
             is ObjCMethodForKotlinMethod -> {} // Handled below.
         }.let {} // Force exhaustive.
     }
@@ -1576,6 +1579,22 @@ private fun ObjCExportCodeGenerator.createEnumValuesAdapter(
     return objCToKotlinMethodAdapter(selector, methodBridge, imp)
 }
 
+private fun ObjCExportCodeGenerator.createThrowableAsErrorAdapter(): ObjCExportCodeGenerator.ObjCToKotlinMethodAdapter {
+    val methodBridge = MethodBridge(
+            returnBridge = MethodBridge.ReturnValue.Mapped(ReferenceBridge),
+            receiver = MethodBridgeReceiver.Instance,
+            valueParameters = emptyList()
+    )
+
+    val imp = generateObjCImpBy(methodBridge) {
+        val exception = objCReferenceToKotlin(param(0), Lifetime.ARGUMENT)
+        ret(callFromBridge(context.llvm.Kotlin_ObjCExport_WrapExceptionToNSError, listOf(exception)))
+    }
+
+    val selector = ObjCExportNamer.kotlinThrowableAsErrorMethodName
+    return objCToKotlinMethodAdapter(selector, methodBridge, imp)
+}
+
 private fun objCFunctionType(context: Context, methodBridge: MethodBridge): LLVMTypeRef {
     val paramTypes = methodBridge.paramBridges.map { it.objCType }
 

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

@@ -9,6 +9,7 @@ import org.jetbrains.kotlin.backend.konan.descriptors.contributedMethods
 import org.jetbrains.kotlin.backend.konan.descriptors.enumEntries
 import org.jetbrains.kotlin.backend.konan.descriptors.isArray
 import org.jetbrains.kotlin.backend.konan.descriptors.isInterface
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.util.SymbolTable
@@ -88,6 +89,10 @@ internal fun ObjCExportedInterface.createCodeSpec(symbolTable: SymbolTable): Obj
                 }
             }
 
+            if (KotlinBuiltIns.isThrowable(descriptor)) {
+                methods += ObjCKotlinThrowableAsErrorMethod
+            }
+
             val categoryMethods = categoryMembers[descriptor].orEmpty().toObjCMethods()
 
             val superClassNotAny = descriptor.getSuperClassNotAny()
@@ -149,6 +154,8 @@ internal class ObjCClassMethodForKotlinEnumValues(
 
 internal class ObjCGetterForObjectInstance(val selector: String) : ObjCMethodSpec()
 
+internal object ObjCKotlinThrowableAsErrorMethod : ObjCMethodSpec()
+
 internal sealed class ObjCTypeSpec(val binaryName: String)
 
 internal sealed class ObjCTypeForKotlinType(

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

@@ -386,6 +386,10 @@ internal class ObjCExportTranslatorImpl(
             }
 
             translateClassMembers(descriptor, genericExportScope)
+
+            if (KotlinBuiltIns.isThrowable(descriptor)) {
+                add { buildThrowableAsErrorMethod() }
+            }
         }
 
         val attributes = if (descriptor.isFinalOrEnum) listOf(OBJC_SUBCLASSING_RESTRICTED) else emptyList()
@@ -406,6 +410,18 @@ internal class ObjCExportTranslatorImpl(
         )
     }
 
+    private fun buildThrowableAsErrorMethod(): ObjCMethod {
+        val asError = ObjCExportNamer.kotlinThrowableAsErrorMethodName
+        return ObjCMethod(
+                descriptor = null,
+                isInstanceMethod = true,
+                returnType = ObjCClassType("NSError"),
+                selectors = listOf(asError),
+                parameters = emptyList(),
+                attributes = listOf(swiftNameAttribute("$asError()"))
+        )
+    }
+
     private fun mapTypeConstructorParameters(descriptor: ClassDescriptor): List<ObjCGenericTypeParameterDeclaration> {
         if (objcGenerics) {
             return descriptor.typeConstructor.parameters.map {

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

@@ -66,6 +66,10 @@ interface ObjCExportNamer {
     val mutableSetName: ClassOrProtocolName
     val mutableMapName: ClassOrProtocolName
     val kotlinNumberName: ClassOrProtocolName
+
+    companion object {
+        internal val kotlinThrowableAsErrorMethodName: String = "asError"
+    }
 }
 
 fun createNamer(moduleDescriptor: ModuleDescriptor,

kotlin-native/backend.native/tests/objcexport/expectedLazy.h

@@ -805,6 +805,44 @@ __attribute__((swift_name("OverrideMethodsOfAnyKt")))
 + (BOOL)testObj:(id)obj other:(id)other swift:(BOOL)swift error:(NSError * _Nullable * _Nullable)error __attribute__((swift_name("test(obj:other:swift:)")));
 @end;
 
+__attribute__((objc_subclassing_restricted))
+__attribute__((swift_name("ThrowableAsError")))
+@interface KtThrowableAsError : KtKotlinThrowable
+- (instancetype)init __attribute__((swift_name("init()"))) __attribute__((objc_designated_initializer));
++ (instancetype)new __attribute__((availability(swift, unavailable, message="use object initializers instead")));
+- (instancetype)initWithMessage:(NSString * _Nullable)message __attribute__((swift_name("init(message:)"))) __attribute__((objc_designated_initializer)) __attribute__((unavailable));
+- (instancetype)initWithCause:(KtKotlinThrowable * _Nullable)cause __attribute__((swift_name("init(cause:)"))) __attribute__((objc_designated_initializer)) __attribute__((unavailable));
+- (instancetype)initWithMessage:(NSString * _Nullable)message cause:(KtKotlinThrowable * _Nullable)cause __attribute__((swift_name("init(message:cause:)"))) __attribute__((objc_designated_initializer)) __attribute__((unavailable));
+@end;
+
+__attribute__((swift_name("ThrowsThrowableAsError")))
+@protocol KtThrowsThrowableAsError
+@required
+
+/**
+ @note This method converts all Kotlin exceptions to errors.
+*/
+- (BOOL)throwErrorAndReturnError:(NSError * _Nullable * _Nullable)error __attribute__((swift_name("throwError()")));
+@end;
+
+__attribute__((swift_name("ThrowsThrowableAsErrorSuspend")))
+@protocol KtThrowsThrowableAsErrorSuspend
+@required
+
+/**
+ @note This method converts instances of CancellationException to errors.
+ Other uncaught Kotlin exceptions are fatal.
+*/
+- (void)throwErrorWithCompletionHandler:(void (^)(KtKotlinUnit * _Nullable, NSError * _Nullable))completionHandler __attribute__((swift_name("throwError(completionHandler:)")));
+@end;
+
+__attribute__((objc_subclassing_restricted))
+__attribute__((swift_name("ThrowableAsErrorKt")))
+@interface KtThrowableAsErrorKt : KtBase
++ (KtThrowableAsError * _Nullable)callAndCatchThrowableAsErrorThrowsThrowableAsError:(id<KtThrowsThrowableAsError>)throwsThrowableAsError __attribute__((swift_name("callAndCatchThrowableAsError(throwsThrowableAsError:)")));
++ (KtThrowableAsError * _Nullable)callAndCatchThrowableAsErrorSuspendThrowsThrowableAsErrorSuspend:(id<KtThrowsThrowableAsErrorSuspend>)throwsThrowableAsErrorSuspend __attribute__((swift_name("callAndCatchThrowableAsErrorSuspend(throwsThrowableAsErrorSuspend:)")));
+@end;
+
 __attribute__((objc_subclassing_restricted))
 __attribute__((swift_name("ThrowsEmptyKt")))
 @interface KtThrowsEmptyKt : KtBase

kotlin-native/backend.native/tests/objcexport/expectedLazyNoGenerics.h

@@ -778,6 +778,44 @@ __attribute__((swift_name("OverrideMethodsOfAnyKt")))
 + (BOOL)testObj:(id)obj other:(id)other swift:(BOOL)swift error:(NSError * _Nullable * _Nullable)error __attribute__((swift_name("test(obj:other:swift:)")));
 @end;
 
+__attribute__((objc_subclassing_restricted))
+__attribute__((swift_name("ThrowableAsError")))
+@interface KtThrowableAsError : KtKotlinThrowable
+- (instancetype)init __attribute__((swift_name("init()"))) __attribute__((objc_designated_initializer));
++ (instancetype)new __attribute__((availability(swift, unavailable, message="use object initializers instead")));
+- (instancetype)initWithMessage:(NSString * _Nullable)message __attribute__((swift_name("init(message:)"))) __attribute__((objc_designated_initializer)) __attribute__((unavailable));
+- (instancetype)initWithCause:(KtKotlinThrowable * _Nullable)cause __attribute__((swift_name("init(cause:)"))) __attribute__((objc_designated_initializer)) __attribute__((unavailable));
+- (instancetype)initWithMessage:(NSString * _Nullable)message cause:(KtKotlinThrowable * _Nullable)cause __attribute__((swift_name("init(message:cause:)"))) __attribute__((objc_designated_initializer)) __attribute__((unavailable));
+@end;
+
+__attribute__((swift_name("ThrowsThrowableAsError")))
+@protocol KtThrowsThrowableAsError
+@required
+
+/**
+ @note This method converts all Kotlin exceptions to errors.
+*/
+- (BOOL)throwErrorAndReturnError:(NSError * _Nullable * _Nullable)error __attribute__((swift_name("throwError()")));
+@end;
+
+__attribute__((swift_name("ThrowsThrowableAsErrorSuspend")))
+@protocol KtThrowsThrowableAsErrorSuspend
+@required
+
+/**
+ @note This method converts instances of CancellationException to errors.
+ Other uncaught Kotlin exceptions are fatal.
+*/
+- (void)throwErrorWithCompletionHandler:(void (^)(KtKotlinUnit * _Nullable, NSError * _Nullable))completionHandler __attribute__((swift_name("throwError(completionHandler:)")));
+@end;
+
+__attribute__((objc_subclassing_restricted))
+__attribute__((swift_name("ThrowableAsErrorKt")))
+@interface KtThrowableAsErrorKt : KtBase
++ (KtThrowableAsError * _Nullable)callAndCatchThrowableAsErrorThrowsThrowableAsError:(id<KtThrowsThrowableAsError>)throwsThrowableAsError __attribute__((swift_name("callAndCatchThrowableAsError(throwsThrowableAsError:)")));
++ (KtThrowableAsError * _Nullable)callAndCatchThrowableAsErrorSuspendThrowsThrowableAsErrorSuspend:(id<KtThrowsThrowableAsErrorSuspend>)throwsThrowableAsErrorSuspend __attribute__((swift_name("callAndCatchThrowableAsErrorSuspend(throwsThrowableAsErrorSuspend:)")));
+@end;
+
 __attribute__((objc_subclassing_restricted))
 __attribute__((swift_name("ThrowsEmptyKt")))
 @interface KtThrowsEmptyKt : KtBase

kotlin-native/backend.native/tests/objcexport/throwableAsError.kt

@@ -0,0 +1,38 @@
+package throwableAsError
+
+import kotlin.coroutines.*
+
+class ThrowableAsError : Throwable()
+
+interface ThrowsThrowableAsError {
+    @Throws(Throwable::class)
+    fun throwError()
+}
+
+fun callAndCatchThrowableAsError(throwsThrowableAsError: ThrowsThrowableAsError): ThrowableAsError? {
+    try {
+        throwsThrowableAsError.throwError()
+    } catch (e: ThrowableAsError) {
+        return e
+    }
+
+    return null
+}
+
+interface ThrowsThrowableAsErrorSuspend {
+    suspend fun throwError()
+}
+
+fun callAndCatchThrowableAsErrorSuspend(throwsThrowableAsErrorSuspend: ThrowsThrowableAsErrorSuspend): ThrowableAsError? {
+    var throwable: ThrowableAsError? = null
+    suspend {
+        throwsThrowableAsErrorSuspend.throwError()
+    }.startCoroutine(object : Continuation<Unit> {
+        override val context = EmptyCoroutineContext
+        override fun resumeWith(result: Result<Unit>) {
+            throwable = result.exceptionOrNull() as? ThrowableAsError
+        }
+    })
+
+    return throwable
+}

kotlin-native/backend.native/tests/objcexport/throwableAsError.swift

@@ -0,0 +1,54 @@
+import Kt
+
+private func testUnwrapsToSame() throws {
+    let throwable = ThrowableAsError()
+    try assertSame(actual: throwable.asError().kotlinException as AnyObject, expected: throwable)
+}
+
+private func testCanThrowAndCatch() throws {
+    let throwable = ThrowableAsError()
+    let impl = ThrowsThrowableAsErrorImpl(throwable: throwable)
+    let caught = ThrowableAsErrorKt.callAndCatchThrowableAsError(throwsThrowableAsError: impl)
+    try assertSame(actual: caught, expected: throwable)
+}
+
+private class ThrowsThrowableAsErrorImpl : ThrowsThrowableAsError {
+    var throwable: KotlinThrowable
+
+    init(throwable: KotlinThrowable) {
+        self.throwable = throwable
+    }
+
+    func throwError() throws {
+        throw throwable.asError()
+    }
+}
+
+private func testCanThrowAndCatchSuspend() throws {
+    let throwable = ThrowableAsError()
+    let impl = ThrowsThrowableAsErrorSuspendImpl(throwable: throwable)
+    let caught = ThrowableAsErrorKt.callAndCatchThrowableAsErrorSuspend(throwsThrowableAsErrorSuspend: impl)
+    try assertSame(actual: caught, expected: throwable)
+}
+
+private class ThrowsThrowableAsErrorSuspendImpl : ThrowsThrowableAsErrorSuspend {
+    var throwable: KotlinThrowable
+
+    init(throwable: KotlinThrowable) {
+        self.throwable = throwable
+    }
+
+    func throwError(completionHandler: @escaping (KotlinUnit?, Error?) -> Void) {
+        completionHandler(nil, throwable.asError())
+    }
+}
+
+class ThrowableAsErrorTests : SimpleTestProvider {
+    override init() {
+        super.init()
+
+        test("TestUnwrapsToSame", testUnwrapsToSame)
+        test("TestCanThrowAndCatch", testCanThrowAndCatch)
+        test("TestCanThrowAndCatchSuspend", testCanThrowAndCatchSuspend)
+    }
+}

kotlin-native/runtime/src/main/cpp/ObjCExportErrors.h

@@ -6,4 +6,5 @@
 #import "Types.h"
 
 extern "C" id Kotlin_ObjCExport_ExceptionAsNSError(KRef exception, const TypeInfo** types);
+extern "C" id Kotlin_ObjCExport_WrapExceptionToNSError(KRef exception);
 extern "C" OBJ_GETTER(Kotlin_ObjCExport_NSErrorAsException, id error);

kotlin-native/runtime/src/main/cpp/ObjCExportErrors.mm

@@ -70,6 +70,10 @@ extern "C" id Kotlin_ObjCExport_ExceptionAsNSError(KRef exception, const TypeInf
     TerminateWithUnhandledException(exception);
   }
 
+  return Kotlin_ObjCExport_WrapExceptionToNSError(exception);
+}
+
+extern "C" id Kotlin_ObjCExport_WrapExceptionToNSError(KRef exception) {
   NSMutableDictionary<NSErrorUserInfoKey, id>* userInfo = [[NSMutableDictionary new] autorelease];
   userInfo[@"KotlinException"] = Kotlin_ObjCExport_refToObjC(exception);
   userInfo[@"KotlinExceptionOrigin"] = @(&kotlinExceptionOriginChar); // Support for different Kotlin runtimes loaded.