Native: don't generate .companion in ObjCExport if the companion is not exported

^KT-47462 Fixed

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

@@ -78,7 +78,7 @@ internal fun ObjCExportedInterface.createCodeSpec(symbolTable: SymbolTable): Obj
                 methods += ObjCGetterForObjectInstance(namer.getObjectPropertySelector(descriptor), irClassSymbol)
             }
 
-            if (descriptor.needCompanionObjectProperty(namer)) {
+            if (descriptor.needCompanionObjectProperty(namer, mapper)) {
                 methods += ObjCGetterForObjectInstance(namer.getCompanionObjectPropertySelector(descriptor),
                         symbolTable.referenceClass(descriptor.companionObjectDescriptor!!))
             }

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

@@ -352,7 +352,7 @@ internal class ObjCExportTranslatorImpl(
                         }
                     }
 
-            if (descriptor.needCompanionObjectProperty(namer)) {
+            if (descriptor.needCompanionObjectProperty(namer, mapper)) {
                 add {
                     ObjCProperty(
                             ObjCExportNamer.companionObjectPropertyName, null,
@@ -1326,8 +1326,15 @@ private fun computeSuperClassType(descriptor: ClassDescriptor): KotlinType? = de
 
 internal const val OBJC_SUBCLASSING_RESTRICTED = "objc_subclassing_restricted"
 
-internal fun ClassDescriptor.needCompanionObjectProperty(namer: ObjCExportNamer) = hasCompanionObject &&
-        (kind != ClassKind.ENUM_CLASS || enumEntries.all { namer.getEnumEntrySelector(it) != ObjCExportNamer.companionObjectPropertyName })
+internal fun ClassDescriptor.needCompanionObjectProperty(namer: ObjCExportNamer, mapper: ObjCExportMapper): Boolean {
+    val companionObject = companionObjectDescriptor
+    if (companionObject == null || !mapper.shouldBeExposed(companionObject)) return false
+
+    if (kind == ClassKind.ENUM_CLASS && enumEntries.any { namer.getEnumEntrySelector(it) == ObjCExportNamer.companionObjectPropertyName })
+        return false // 'companion' property would clash with enum entry, don't generate it.
+
+    return true
+}
 
 
 private fun Deprecation.toDeprecationAttribute(): String {

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

@@ -857,6 +857,22 @@ __attribute__((swift_name("KT43780Enum.Companion")))
 @property (readonly) int32_t x __attribute__((swift_name("x")));
 @end;
 
+__attribute__((objc_subclassing_restricted))
+__attribute__((swift_name("ClassWithInternalCompanion")))
+@interface KtClassWithInternalCompanion : KtBase
+- (instancetype)init __attribute__((swift_name("init()"))) __attribute__((objc_designated_initializer));
++ (instancetype)new __attribute__((availability(swift, unavailable, message="use object initializers instead")));
+@property (readonly) int32_t y __attribute__((swift_name("y")));
+@end;
+
+__attribute__((objc_subclassing_restricted))
+__attribute__((swift_name("ClassWithPrivateCompanion")))
+@interface KtClassWithPrivateCompanion : KtBase
+- (instancetype)init __attribute__((swift_name("init()"))) __attribute__((objc_designated_initializer));
++ (instancetype)new __attribute__((availability(swift, unavailable, message="use object initializers instead")));
+@property (readonly) int32_t y __attribute__((swift_name("y")));
+@end;
+
 __attribute__((swift_name("Host")))
 @protocol KtHost
 @required

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

@@ -799,6 +799,22 @@ __attribute__((swift_name("KT43780Enum.Companion")))
 @property (readonly) int32_t x __attribute__((swift_name("x")));
 @end;
 
+__attribute__((objc_subclassing_restricted))
+__attribute__((swift_name("ClassWithInternalCompanion")))
+@interface KtClassWithInternalCompanion : KtBase
+- (instancetype)init __attribute__((swift_name("init()"))) __attribute__((objc_designated_initializer));
++ (instancetype)new __attribute__((availability(swift, unavailable, message="use object initializers instead")));
+@property (readonly) int32_t y __attribute__((swift_name("y")));
+@end;
+
+__attribute__((objc_subclassing_restricted))
+__attribute__((swift_name("ClassWithPrivateCompanion")))
+@interface KtClassWithPrivateCompanion : KtBase
+- (instancetype)init __attribute__((swift_name("init()"))) __attribute__((objc_designated_initializer));
++ (instancetype)new __attribute__((availability(swift, unavailable, message="use object initializers instead")));
+@property (readonly) int32_t y __attribute__((swift_name("y")));
+@end;
+
 __attribute__((swift_name("Host")))
 @protocol KtHost
 @required

kotlin-native/backend.native/tests/objcexport/kt43780.kt

@@ -34,4 +34,29 @@ enum class KT43780Enum {
     companion object {
         val x = 11
     }
-}
+}
+
+class ClassWithInternalCompanion {
+    internal companion object {
+        val x = 12
+    }
+
+    val y = 13
+}
+
+class ClassWithPrivateCompanion {
+    private companion object {
+        val x = 14
+    }
+
+    val y = 15
+}
+
+// Shouldn't be exported at all:
+internal class InternalClassWithCompanion {
+    companion object
+}
+
+private class PrivateClassWithCompanion {
+    companion object
+}

kotlin-native/backend.native/tests/objcexport/kt43780.swift

@@ -37,6 +37,14 @@ private func testNameClash() throws {
     try assertEquals(actual: KT43780Enum.otherEntry.name, expected: "OTHER_ENTRY")
 }
 
+// Reported as https://youtrack.jetbrains.com/issue/KT-47462
+private func testUnexposedCompanion() throws {
+    // Just trying to ensure that the classes are accessible:
+    try assertEquals(actual: 13, expected: ClassWithInternalCompanion().y)
+    try assertEquals(actual: 15, expected: ClassWithPrivateCompanion().y)
+    // and this doesn't make the companions accessible as well.
+}
+
 
 class Kt43780Tests : SimpleTestProvider {
     override init() {
@@ -45,5 +53,6 @@ class Kt43780Tests : SimpleTestProvider {
         test("testObject", testObject)
         test("testCompanionObject", testCompanionObject)
         test("testNameClash", testNameClash)
+        test("testUnexposedCompanion", testUnexposedCompanion)
     }
 }