Generate 'Deprecated' annotation on invisible companion object field

Design decision: if the field for a companion object should have
non-public visibility, generate it with @Deprecated annotation in
language version 1.2.

TODO: generate it with proper visibility in 1.3 and later.

KT-11567 Companion object INSTANCE field more visible than companion object class itself

compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java

@@ -35,6 +35,7 @@ import org.jetbrains.kotlin.codegen.signature.BothSignatureWriter;
 import org.jetbrains.kotlin.codegen.signature.JvmSignatureWriter;
 import org.jetbrains.kotlin.codegen.state.GenerationState;
 import org.jetbrains.kotlin.codegen.state.KotlinTypeMapper;
+import org.jetbrains.kotlin.config.LanguageFeature;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation;
 import org.jetbrains.kotlin.lexer.KtTokens;
@@ -64,10 +65,7 @@ import org.jetbrains.kotlin.resolve.scopes.receivers.ExtensionReceiver;
 import org.jetbrains.kotlin.resolve.scopes.receivers.ImplicitReceiver;
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue;
 import org.jetbrains.kotlin.types.KotlinType;
-import org.jetbrains.org.objectweb.asm.FieldVisitor;
+import org.jetbrains.org.objectweb.asm.*;
-import org.jetbrains.org.objectweb.asm.Label;
-import org.jetbrains.org.objectweb.asm.MethodVisitor;
-import org.jetbrains.org.objectweb.asm.Type;
 import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter;
 import org.jetbrains.org.objectweb.asm.commons.Method;
 
@@ -838,9 +836,21 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
 
         @Nullable KtObjectDeclaration companionObject = CollectionsKt.firstOrNull(myClass.getCompanionObjects());
 
+        int properFieldVisibilityFlag = getVisibilityAccessFlag(companionObjectDescriptor);
+        boolean fieldShouldBeDeprecated =
+                state.getLanguageVersionSettings().supportsFeature(LanguageFeature.DeprecatedFieldForInvisibleCompanionObject) &&
+                (properFieldVisibilityFlag & (ACC_PRIVATE | ACC_PROTECTED)) != 0;
+        // TODO generate field with proper visibility in language version 1.3
+        int fieldAccessFlags = ACC_PUBLIC | ACC_STATIC | ACC_FINAL;
+        if (fieldShouldBeDeprecated) {
+            fieldAccessFlags |= ACC_DEPRECATED;
+        }
         StackValue.Field field = StackValue.singleton(companionObjectDescriptor, typeMapper);
-        v.newField(JvmDeclarationOriginKt.OtherOrigin(companionObject == null ? myClass.getPsiOrParent() : companionObject),
+        FieldVisitor fv = v.newField(JvmDeclarationOriginKt.OtherOrigin(companionObject == null ? myClass.getPsiOrParent() : companionObject),
-                   ACC_PUBLIC | ACC_STATIC | ACC_FINAL, field.name, field.type.getDescriptor(), null, null);
+                                     fieldAccessFlags, field.name, field.type.getDescriptor(), null, null);
+        if (fieldShouldBeDeprecated) {
+            AnnotationCodegen.forField(fv, this, typeMapper).visitAnnotation("Ljava/lang/Deprecated;", true).visitEnd();
+        }
     }
 
     private void generateCompanionObjectBackingFieldCopies() {

compiler/testData/codegen/bytecodeListing/invisibleCompanionObject.kt

@@ -0,0 +1,13 @@
+// LANGUAGE_VERSION: 1.2
+
+class TestPrivateCompanion {
+    private companion object Test
+}
+
+open class TestProtectedCompanion {
+    protected companion object Test
+}
+
+class TestInternalCompanion {
+    internal companion object Test
+}

compiler/testData/codegen/bytecodeListing/invisibleCompanionObject.txt

@@ -0,0 +1,44 @@
+@kotlin.Metadata
+public final class TestInternalCompanion$Test {
+    inner class TestInternalCompanion$Test
+    private method <init>(): void
+    public synthetic method <init>(p0: kotlin.jvm.internal.DefaultConstructorMarker): void
+}
+
+@kotlin.Metadata
+public final class TestInternalCompanion {
+    public final static field Test: TestInternalCompanion$Test
+    inner class TestInternalCompanion$Test
+    static method <clinit>(): void
+    public method <init>(): void
+}
+
+@kotlin.Metadata
+final class TestPrivateCompanion$Test {
+    inner class TestPrivateCompanion$Test
+    private method <init>(): void
+    public synthetic method <init>(p0: kotlin.jvm.internal.DefaultConstructorMarker): void
+}
+
+@kotlin.Metadata
+public final class TestPrivateCompanion {
+    public deprecated final static @java.lang.Deprecated field Test: TestPrivateCompanion$Test
+    inner class TestPrivateCompanion$Test
+    static method <clinit>(): void
+    public method <init>(): void
+}
+
+@kotlin.Metadata
+public final class TestProtectedCompanion$Test {
+    inner class TestProtectedCompanion$Test
+    private method <init>(): void
+    public synthetic method <init>(p0: kotlin.jvm.internal.DefaultConstructorMarker): void
+}
+
+@kotlin.Metadata
+public class TestProtectedCompanion {
+    public deprecated final static @java.lang.Deprecated field Test: TestProtectedCompanion$Test
+    inner class TestProtectedCompanion$Test
+    static method <clinit>(): void
+    public method <init>(): void
+}

compiler/testData/codegen/bytecodeListing/invisibleCompanionObject_lv11.kt

@@ -0,0 +1,13 @@
+// LANGUAGE_VERSION: 1.1
+
+class TestPrivateCompanion {
+    private companion object Test
+}
+
+open class TestProtectedCompanion {
+    protected companion object Test
+}
+
+class TestInternalCompanion {
+    internal companion object Test
+}

compiler/testData/codegen/bytecodeListing/invisibleCompanionObject_lv11.txt

@@ -0,0 +1,44 @@
+@kotlin.Metadata
+public final class TestInternalCompanion$Test {
+    inner class TestInternalCompanion$Test
+    private method <init>(): void
+    public synthetic method <init>(p0: kotlin.jvm.internal.DefaultConstructorMarker): void
+}
+
+@kotlin.Metadata
+public final class TestInternalCompanion {
+    public final static field Test: TestInternalCompanion$Test
+    inner class TestInternalCompanion$Test
+    static method <clinit>(): void
+    public method <init>(): void
+}
+
+@kotlin.Metadata
+final class TestPrivateCompanion$Test {
+    inner class TestPrivateCompanion$Test
+    private method <init>(): void
+    public synthetic method <init>(p0: kotlin.jvm.internal.DefaultConstructorMarker): void
+}
+
+@kotlin.Metadata
+public final class TestPrivateCompanion {
+    public final static field Test: TestPrivateCompanion$Test
+    inner class TestPrivateCompanion$Test
+    static method <clinit>(): void
+    public method <init>(): void
+}
+
+@kotlin.Metadata
+public final class TestProtectedCompanion$Test {
+    inner class TestProtectedCompanion$Test
+    private method <init>(): void
+    public synthetic method <init>(p0: kotlin.jvm.internal.DefaultConstructorMarker): void
+}
+
+@kotlin.Metadata
+public class TestProtectedCompanion {
+    public final static field Test: TestProtectedCompanion$Test
+    inner class TestProtectedCompanion$Test
+    static method <clinit>(): void
+    public method <init>(): void
+}

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeListingTestGenerated.java

@@ -90,6 +90,18 @@ public class BytecodeListingTestGenerated extends AbstractBytecodeListingTest {
         doTest(fileName);
     }
 
+    @TestMetadata("invisibleCompanionObject.kt")
+    public void testInvisibleCompanionObject() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeListing/invisibleCompanionObject.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("invisibleCompanionObject_lv11.kt")
+    public void testInvisibleCompanionObject_lv11() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeListing/invisibleCompanionObject_lv11.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("jvmOverloadsAndParametersAnnotations.kt")
     public void testJvmOverloadsAndParametersAnnotations() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeListing/jvmOverloadsAndParametersAnnotations.kt");

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -52,6 +52,7 @@ enum class LanguageFeature(
     ArrayLiteralsInAnnotations(KOTLIN_1_2),
     InlineDefaultFunctionalParameters(KOTLIN_1_2),
     SoundSmartCastsAfterTry(KOTLIN_1_2),
+    DeprecatedFieldForInvisibleCompanionObject(KOTLIN_1_2),
 
     // Experimental features