[K/N] KT-56464: implementation of HiddenFromObjC for classes in backend

compiler/fir/checkers/checkers.native/src/org/jetbrains/kotlin/fir/analysis/diagnostics/native/FirNativeErrorsDefaultMessages.kt

@@ -61,7 +61,7 @@ object FirNativeErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
         )
         map.put(
             INVALID_OBJC_REFINEMENT_TARGETS,
-            "Refines annotations are only applicable to annotations with targets FUNCTION and/or PROPERTY"
+            "Refines annotations are only applicable to annotations with targets CLASS, FUNCTION and/or PROPERTY"
         )
         map.put(INAPPLICABLE_OBJC_NAME, "@ObjCName is not applicable on overrides")
         map.put(INVALID_OBJC_NAME, "@ObjCName should have a name and/or swiftName")

compiler/fir/checkers/checkers.native/src/org/jetbrains/kotlin/fir/analysis/native/checkers/FirNativeObjCRefinementAnnotationChecker.kt

@@ -21,7 +21,7 @@ import org.jetbrains.kotlin.fir.expressions.FirAnnotation
 
 object FirNativeObjCRefinementAnnotationChecker : FirRegularClassChecker() {
 
-    private val supportedTargets = arrayOf(KotlinTarget.FUNCTION, KotlinTarget.PROPERTY)
+    private val supportedTargets = arrayOf(KotlinTarget.FUNCTION, KotlinTarget.PROPERTY, KotlinTarget.CLASS)
 
     override fun check(declaration: FirRegularClass, context: CheckerContext, reporter: DiagnosticReporter) {
         if (declaration.classKind != ClassKind.ANNOTATION_CLASS) return

compiler/testData/diagnostics/nativeTests/objCRefinement.kt

@@ -25,7 +25,7 @@ public annotation class ShouldRefineInSwift
 package plugin
 
 @HidesFromObjC
-@Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION)
+@Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION, AnnotationTarget.CLASS)
 @Retention(AnnotationRetention.BINARY)
 annotation class PluginHiddenFromObjC
 
@@ -45,7 +45,7 @@ import plugin.PluginShouldRefineInSwift
 annotation class MyRefinedAnnotationA
 
 <!INVALID_OBJC_REFINEMENT_TARGETS!>@HidesFromObjC<!>
-@Target(AnnotationTarget.PROPERTY, AnnotationTarget.CLASS)
+@Target(AnnotationTarget.PROPERTY, AnnotationTarget.FILE)
 @Retention(AnnotationRetention.BINARY)
 annotation class MyRefinedAnnotationB
 

compiler/testData/diagnostics/nativeTests/objCRefinement.txt

@@ -88,7 +88,7 @@ public interface InterfaceB {
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
-@kotlin.native.HidesFromObjC @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.PROPERTY, AnnotationTarget.CLASS}) @kotlin.annotation.Retention(value = AnnotationRetention.BINARY) public final annotation class MyRefinedAnnotationB : kotlin.Annotation {
+@kotlin.native.HidesFromObjC @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.PROPERTY, AnnotationTarget.FILE}) @kotlin.annotation.Retention(value = AnnotationRetention.BINARY) public final annotation class MyRefinedAnnotationB : kotlin.Annotation {
     public constructor MyRefinedAnnotationB()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
@@ -146,7 +146,7 @@ package kotlin {
 
 package plugin {
 
-    @kotlin.native.HidesFromObjC @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION}) @kotlin.annotation.Retention(value = AnnotationRetention.BINARY) public final annotation class PluginHiddenFromObjC : kotlin.Annotation {
+    @kotlin.native.HidesFromObjC @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION, AnnotationTarget.CLASS}) @kotlin.annotation.Retention(value = AnnotationRetention.BINARY) public final annotation class PluginHiddenFromObjC : kotlin.Annotation {
         public constructor PluginHiddenFromObjC()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

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

@@ -596,9 +596,36 @@ private class BackendChecker(
         if (declaration.isKotlinObjCClass()) {
             checkKotlinObjCClass(declaration)
         }
+        checkHiddenFromObjCRestrictions(declaration)
         super.visitClass(declaration)
 
     }
+
+    private fun IrClass.isHiddenFromObjC(): Boolean {
+        return annotations.any { annotationCall ->
+            val annotationClass = annotationCall.symbol.owner.parentAsClass
+            annotationClass.annotations.hasAnnotation(KonanFqNames.hidesFromObjC)
+        }
+    }
+
+    private fun checkHiddenFromObjCRestrictions(declaration: IrClass) {
+        // If declaration itself. is marked as hidden, we don't need to do anything
+        if (declaration.isHiddenFromObjC()) return
+        // Enum entries inherit from their classes, so if enum class is marked as hidden, there is no need to
+        // produce additional errors.
+        if (declaration.kind == ClassKind.ENUM_ENTRY) return
+        // Private and local classes does not leak to Objective-C API surface, so it is OK for them
+        // to inherit from hidden types.
+        if (DescriptorVisibilities.isPrivate(declaration.visibility) || declaration.isLocal) return
+        if (declaration.superClass?.isHiddenFromObjC() == true) {
+            reportError(declaration, "Only @HiddenFromObjC declaration can inherit from class annotated with @HiddenFromObjC")
+        }
+        declaration.getSuperInterfaces().forEach {
+            if (it.isHiddenFromObjC()) {
+                reportError(declaration, "Only @HiddenFromObjC declaration can implement interface annotated with @HiddenFromObjC")
+            }
+        }
+    }
 }
 
 private fun BackendChecker.checkCanGenerateCCall(expression: IrCall, isInvoke: Boolean) {

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

@@ -108,6 +108,16 @@ private fun CallableMemberDescriptor.isHiddenFromObjC(): Boolean = when {
     }
 }
 
+/**
+ * Check if the given class or its enclosing declaration is marked as @HiddenFromObjC.
+ */
+internal fun ClassDescriptor.isHiddenFromObjC(): Boolean = when {
+    (this.containingDeclaration as? ClassDescriptor)?.isHiddenFromObjC() == true -> true
+    else -> annotations.any { annotation ->
+        annotation.annotationClass?.annotations?.any { it.fqName == KonanFqNames.hidesFromObjC } == true
+    }
+}
+
 internal fun ObjCExportMapper.shouldBeExposed(descriptor: ClassDescriptor): Boolean =
         shouldBeVisible(descriptor) && !isSpecialMapped(descriptor) && !descriptor.defaultType.isObjCObjectType()
 
@@ -175,7 +185,7 @@ internal fun ObjCExportMapper.shouldBeVisible(descriptor: ClassDescriptor): Bool
         descriptor.isEffectivelyPublicApi && when (descriptor.kind) {
         ClassKind.CLASS, ClassKind.INTERFACE, ClassKind.ENUM_CLASS, ClassKind.OBJECT -> true
         ClassKind.ENUM_ENTRY, ClassKind.ANNOTATION_CLASS -> false
-    } && !descriptor.isExpect && !descriptor.isInlined() && !isHiddenByDeprecation(descriptor)
+    } && !descriptor.isExpect && !descriptor.isInlined() && !isHiddenByDeprecation(descriptor) && !descriptor.isHiddenFromObjC()
 
 private fun ObjCExportMapper.isBase(descriptor: CallableMemberDescriptor): Boolean =
         descriptor.overriddenDescriptors.all { !shouldBeExposed(it) }

kotlin-native/runtime/src/main/kotlin/kotlin/native/Annotations.kt

@@ -107,12 +107,12 @@ public actual annotation class CName(actual val externName: String = "", actual
 public actual annotation class ObjCName(actual val name: String = "", actual val swiftName: String = "", actual val exact: Boolean = false)
 
 /**
- * Meta-annotation that instructs the Kotlin compiler to remove the annotated function or property from the public Objective-C API.
+ * Meta-annotation that instructs the Kotlin compiler to remove the annotated class, function or property from the public Objective-C API.
  *
  * Annotation processors that refine the public Objective-C API can annotate their annotations with this meta-annotation
  * to have the original declarations automatically removed from the public API.
  *
- * Note: only annotations with [AnnotationTarget.FUNCTION] and/or [AnnotationTarget.PROPERTY] are supported.
+ * Note: only annotations with [AnnotationTarget.CLASS], [AnnotationTarget.FUNCTION] and/or [AnnotationTarget.PROPERTY] are supported.
  */
 @Target(AnnotationTarget.ANNOTATION_CLASS)
 @Retention(AnnotationRetention.BINARY)
@@ -122,10 +122,10 @@ public actual annotation class ObjCName(actual val name: String = "", actual val
 public actual annotation class HidesFromObjC
 
 /**
- * Instructs the Kotlin compiler to remove this function or property from the public Objective-C API.
+ * Instructs the Kotlin compiler to remove this class, function or property from the public Objective-C API.
  */
 @HidesFromObjC
-@Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION)
+@Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION, AnnotationTarget.CLASS)
 @Retention(AnnotationRetention.BINARY)
 @MustBeDocumented
 @ExperimentalObjCRefinement

libraries/stdlib/src/kotlin/annotations/NativeAnnotations.kt

@@ -69,12 +69,12 @@ expect annotation class FreezingIsDeprecated
 public expect annotation class ObjCName(val name: String = "", val swiftName: String = "", val exact: Boolean = false)
 
 /**
- * Meta-annotation that instructs the Kotlin compiler to remove the annotated function or property from the public Objective-C API.
+ * Meta-annotation that instructs the Kotlin compiler to remove the annotated class, function or property from the public Objective-C API.
  *
  * Annotation processors that refine the public Objective-C API can annotate their annotations with this meta-annotation
  * to have the original declarations automatically removed from the public API.
  *
- * Note: only annotations with [AnnotationTarget.FUNCTION] and/or [AnnotationTarget.PROPERTY] are supported.
+ * Note: only annotations with [AnnotationTarget.CLASS], [AnnotationTarget.FUNCTION] and/or [AnnotationTarget.PROPERTY] are supported.
  */
 @Target(AnnotationTarget.ANNOTATION_CLASS)
 @Retention(AnnotationRetention.BINARY)
@@ -85,10 +85,10 @@ public expect annotation class ObjCName(val name: String = "", val swiftName: St
 public expect annotation class HidesFromObjC()
 
 /**
- * Instructs the Kotlin compiler to remove this function or property from the public Objective-C API.
+ * Instructs the Kotlin compiler to remove this class, function or property from the public Objective-C API.
  */
 @HidesFromObjC
-@Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION)
+@Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION, AnnotationTarget.CLASS)
 @Retention(AnnotationRetention.BINARY)
 @MustBeDocumented
 @OptionalExpectation

native/frontend/src/org/jetbrains/kotlin/resolve/konan/diagnostics/DefaultErrorMessagesNative.kt

@@ -64,7 +64,7 @@ private val DIAGNOSTIC_FACTORY_TO_RENDERER by lazy {
         )
         put(
             ErrorsNative.INVALID_OBJC_REFINEMENT_TARGETS,
-            "Refines annotations are only applicable to annotations with targets FUNCTION and/or PROPERTY"
+            "Refines annotations are only applicable to annotations with targets CLASS, FUNCTION and/or PROPERTY"
         )
     }
 }

native/frontend/src/org/jetbrains/kotlin/resolve/konan/diagnostics/NativeObjCRefinementAnnotationChecker.kt

@@ -21,7 +21,7 @@ import org.jetbrains.kotlin.resolve.konan.diagnostics.NativeObjCRefinementChecke
 
 object NativeObjCRefinementAnnotationChecker : DeclarationChecker {
 
-    private val supportedTargets = arrayOf(KotlinTarget.FUNCTION, KotlinTarget.PROPERTY)
+    private val supportedTargets = arrayOf(KotlinTarget.FUNCTION, KotlinTarget.PROPERTY, KotlinTarget.CLASS)
 
     override fun check(declaration: KtDeclaration, descriptor: DeclarationDescriptor, context: DeclarationCheckerContext) {
         if (descriptor !is ClassDescriptor || descriptor.kind != ClassKind.ANNOTATION_CLASS) return