Improve ObjCExport type mapping

Support Class type and forward declarations

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

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.backend.konan
 
+import org.jetbrains.kotlin.backend.konan.descriptors.findPackage
 import org.jetbrains.kotlin.backend.konan.descriptors.getArgumentValueOrNull
 import org.jetbrains.kotlin.backend.konan.descriptors.getStringValue
 import org.jetbrains.kotlin.backend.konan.descriptors.getStringValueOrNull
@@ -34,6 +35,7 @@ internal val externalObjCClassFqName = interopPackageName.child(Name.identifier(
 private val objCMethodFqName = interopPackageName.child(Name.identifier("ObjCMethod"))
 private val objCConstructorFqName = FqName("kotlinx.cinterop.ObjCConstructor")
 private val objCFactoryFqName = interopPackageName.child(Name.identifier("ObjCFactory"))
+private val objcnamesForwardDeclarationsPackageName = Name.identifier("objcnames")
 
 @Deprecated("Use IR version rather than descriptor version")
 fun ClassDescriptor.isObjCClass(): Boolean =
@@ -61,6 +63,9 @@ fun IrClass.isExternalObjCClass(): Boolean = this.isObjCClass() &&
             it.descriptor.annotations.hasAnnotation(externalObjCClassFqName)
         }
 
+fun ClassDescriptor.isObjCForwardDeclaration(): Boolean =
+        this.findPackage().fqName.startsWith(objcnamesForwardDeclarationsPackageName)
+
 fun ClassDescriptor.isObjCMetaClass(): Boolean = this.getAllSuperClassifiers().any {
     it.fqNameSafe == objCClassFqName
 }

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

@@ -800,9 +800,9 @@ internal class ObjCExportTranslatorImpl(
     private tailrec fun mapObjCObjectReferenceTypeIgnoringNullability(descriptor: ClassDescriptor): ObjCNonNullReferenceType {
         // TODO: more precise types can be used.
 
-        if (descriptor.isObjCMetaClass()) return ObjCIdType
+        if (descriptor.isObjCMetaClass()) return ObjCMetaClassType
 
-        if (descriptor.isExternalObjCClass()) {
+        if (descriptor.isExternalObjCClass() || descriptor.isObjCForwardDeclaration()) {
             return if (descriptor.isInterface) {
                 val name = descriptor.name.asString().removeSuffix("Protocol")
                 generator?.referenceProtocol(name)

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

@@ -89,6 +89,10 @@ class ObjCBlockPointerType(
     })
 }
 
+object ObjCMetaClassType : ObjCNonNullReferenceType() {
+    override fun render(attrsAndName: String): String = "Class".withAttrsAndName(attrsAndName)
+}
+
 class ObjCPrimitiveType(
         val cName: String
 ) : ObjCType() {

backend.native/tests/framework/values/expectedLazy.h

@@ -600,6 +600,8 @@ __attribute__((swift_name("ValuesKt")))
 + (void (^)(void))asNothingBlockBlock:(id _Nullable (^)(void))block __attribute__((swift_name("asNothingBlock(block:)")));
 + (void (^ _Nullable)(void))getNullBlock __attribute__((swift_name("getNullBlock()")));
 + (BOOL)isBlockNullBlock:(void (^ _Nullable)(void))block __attribute__((swift_name("isBlockNull(block:)")));
++ (void)takeForwardDeclaredClassObj:(ForwardDeclaredClass *)obj __attribute__((swift_name("takeForwardDeclaredClass(obj:)")));
++ (void)takeForwardDeclaredProtocolObj:(id<ForwardDeclared>)obj __attribute__((swift_name("takeForwardDeclaredProtocol(obj:)")));
 @property (class, readonly) double dbl __attribute__((swift_name("dbl")));
 @property (class, readonly) float flt __attribute__((swift_name("flt")));
 @property (class, readonly) int32_t integer __attribute__((swift_name("integer")));

backend.native/tests/framework/values/values.kt

@@ -423,3 +423,6 @@ object UnitBlockCoercionImpl : UnitBlockCoercion<() -> Unit> {
 }
 
 abstract class MyAbstractList : List<Any?>
+
+fun takeForwardDeclaredClass(obj: objcnames.classes.ForwardDeclaredClass) {}
+fun takeForwardDeclaredProtocol(obj: objcnames.protocols.ForwardDeclaredProtocol) {}