[K/N] Fix KT-58839

Do not export extensions of classes that are
hidden from the generated Objective-C API.

Merge-request: KT-MR-10330
Merged-by: Sergey Bogolepov <sergey.bogolepov@jetbrains.com>

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

@@ -1204,7 +1204,11 @@ abstract class ObjCExportHeaderGenerator internal constructor(
                     .forEach {
                         val classDescriptor = mapper.getClassIfCategory(it)
                         if (classDescriptor != null) {
-                            extensions.getOrPut(classDescriptor, { mutableListOf() }) += it
+                            // If a class is hidden from Objective-C API then it is meaningless
+                            // to export its extensions.
+                            if (!classDescriptor.isHiddenFromObjC()) {
+                                extensions.getOrPut(classDescriptor, { mutableListOf() }) += it
+                            }
                         } else {
                             topLevel.getOrPut(it.findSourceFile(), { mutableListOf() }) += it
                         }

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

@@ -182,7 +182,11 @@ internal class ObjCExportLazyImpl(
             if ((it is KtFunction || it is KtProperty) && it.isPublic && !it.hasExpectModifier()) {
                 val classDescriptor = getClassIfExtension(it)
                 if (classDescriptor != null) {
-                    extensions.getOrPut(classDescriptor, { mutableListOf() }) += it
+                    // If a class is hidden from Objective-C API then it is meaningless
+                    // to export its extensions.
+                    if (!classDescriptor.isHiddenFromObjC()) {
+                        extensions.getOrPut(classDescriptor, { mutableListOf() }) += it
+                    }
                 } else {
                     topLevel += it
                 }

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

@@ -756,6 +756,7 @@ __attribute__((swift_name("WrapperOverUnavailable")))
 __attribute__((objc_subclassing_restricted))
 __attribute__((swift_name("HiddenfromobjcKt")))
 @interface KtHiddenfromobjcKt : KtBase
++ (id)doSomethingMeaningless:(NSString *)receiver another:(id)another __attribute__((swift_name("doSomethingMeaningless(_:another:)")));
 + (id)useOfUnavailableClassParam:(id)param __attribute__((swift_name("useOfUnavailableClass(param:)")));
 + (id _Nullable)useOfNullableUnavailableClassParam:(id _Nullable)param __attribute__((swift_name("useOfNullableUnavailableClass(param:)")));
 + (id)produceUnavailable __attribute__((swift_name("produceUnavailable()")));

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

@@ -756,6 +756,7 @@ __attribute__((swift_name("WrapperOverUnavailable")))
 __attribute__((objc_subclassing_restricted))
 __attribute__((swift_name("HiddenfromobjcKt")))
 @interface KtHiddenfromobjcKt : KtBase
++ (id)doSomethingMeaningless:(NSString *)receiver another:(id)another __attribute__((swift_name("doSomethingMeaningless(_:another:)")));
 + (id)useOfUnavailableClassParam:(id)param __attribute__((swift_name("useOfUnavailableClass(param:)")));
 + (id _Nullable)useOfNullableUnavailableClassParam:(id _Nullable)param __attribute__((swift_name("useOfNullableUnavailableClass(param:)")));
 + (id)produceUnavailable __attribute__((swift_name("produceUnavailable()")));

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

@@ -756,6 +756,7 @@ __attribute__((swift_name("WrapperOverUnavailable")))
 __attribute__((objc_subclassing_restricted))
 __attribute__((swift_name("HiddenfromobjcKt")))
 @interface KtHiddenfromobjcKt : KtBase
++ (id)doSomethingMeaningless:(NSString *)receiver another:(id)another __attribute__((swift_name("doSomethingMeaningless(_:another:)")));
 + (id)useOfUnavailableClassParam:(id)param __attribute__((swift_name("useOfUnavailableClass(param:)")));
 + (id _Nullable)useOfNullableUnavailableClassParam:(id _Nullable)param __attribute__((swift_name("useOfNullableUnavailableClass(param:)")));
 + (id)produceUnavailable __attribute__((swift_name("produceUnavailable()")));

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

@@ -11,6 +11,15 @@ import kotlin.experimental.ExperimentalObjCRefinement
 @HiddenFromObjC
 data class ClassNotAvailableInSwift(val param: String)
 
+// KT-58839
+fun ClassNotAvailableInSwift.doSomethingMeaningless(another: ClassNotAvailableInSwift): ClassNotAvailableInSwift {
+    return ClassNotAvailableInSwift(this.param + another.param)
+}
+
+fun String.doSomethingMeaningless(another: ClassNotAvailableInSwift): ClassNotAvailableInSwift {
+    return ClassNotAvailableInSwift(this + another.param)
+}
+
 // Check that inner and nested classes are hidden if enclosing class is hidden
 @OptIn(ExperimentalObjCRefinement::class)
 @HiddenFromObjC