KT-52592 Fix NPE from KProperty.getExtensionDelegate on property delegated to another property; make $delegate methods private

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -42723,6 +42723,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                     runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegate.kt");
                 }
 
+                @Test
+                @TestMetadata("getExtensionDelegateForDelegatedToAnother.kt")
+                public void testGetExtensionDelegateForDelegatedToAnother() throws Exception {
+                    runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegateForDelegatedToAnother.kt");
+                }
+
                 @Test
                 @TestMetadata("kPropertyForDelegatedProperty.kt")
                 public void testKPropertyForDelegatedProperty() throws Exception {

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmPropertiesLowering.kt

@@ -16,6 +16,8 @@ import org.jetbrains.kotlin.backend.jvm.ir.needsAccessor
 import org.jetbrains.kotlin.backend.jvm.requiresMangling
 import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
+import org.jetbrains.kotlin.descriptors.DescriptorVisibility
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
@@ -167,7 +169,7 @@ class JvmPropertiesLowering(private val backendContext: JvmBackendContext) : IrE
             JvmLoweredDeclarationOrigin.SYNTHETIC_METHOD_FOR_PROPERTY_OR_TYPEALIAS_ANNOTATIONS,
             // TODO: technically JVM permits having fields with same name but different type, so we could potentially
             //   generate two properties like that; should this be the getter's return type instead?
-            isStatic = true, returnType = backendContext.irBuiltIns.unitType
+            isStatic = true, returnType = backendContext.irBuiltIns.unitType, visibility = declaration.visibility
         ).apply {
             body = IrBlockBodyImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET)
             annotations = declaration.annotations
@@ -179,13 +181,14 @@ class JvmPropertiesLowering(private val backendContext: JvmBackendContext) : IrE
             suffix: String,
             origin: IrDeclarationOrigin,
             isStatic: Boolean,
-            returnType: IrType
+            returnType: IrType,
+            visibility: DescriptorVisibility
         ) = irFactory.buildFun {
             name = Name.identifier(computeSyntheticMethodName(declaration, suffix))
             modality = Modality.OPEN
-            visibility = declaration.visibility
             this.origin = origin
             this.returnType = returnType
+            this.visibility = visibility
         }.apply {
             if (!isStatic) {
                 dispatchReceiverParameter = declaration.getter?.dispatchReceiverParameter?.let {
@@ -207,7 +210,7 @@ class JvmPropertiesLowering(private val backendContext: JvmBackendContext) : IrE
                 declaration,
                 JvmAbi.DELEGATED_PROPERTY_NAME_SUFFIX,
                 IrDeclarationOrigin.PROPERTY_DELEGATE,
-                isStatic = false, returnType = irBuiltIns.anyNType
+                isStatic = false, returnType = irBuiltIns.anyNType, visibility = DescriptorVisibilities.PRIVATE
             )
 
         private fun JvmBackendContext.computeSyntheticMethodName(property: IrProperty, suffix: String): String {

compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegateForDelegatedToAnother.kt

@@ -0,0 +1,16 @@
+// TARGET_BACKEND: JVM
+// WITH_REFLECT
+
+import kotlin.reflect.full.getExtensionDelegate
+import kotlin.reflect.jvm.isAccessible
+import kotlin.test.assertEquals
+
+class A
+
+val A.x: Int get() = 1
+val A.y: Int by A::x
+
+fun box(): String {
+    assertEquals(A::x, A::y.apply { isAccessible = true }.getExtensionDelegate())
+    return "OK"
+}

compiler/testData/codegen/box/reflection/properties/getDelegate/noSetAccessibleTrue.kt

@@ -11,11 +11,15 @@ object Delegate {
 }
 
 val topLevel: Boolean by Delegate
+val delegated: Boolean by ::topLevel
 val String.extension: Boolean by Delegate
+val String.delegated: Boolean by String::delegated
 
 class Foo {
     val member: Boolean by Delegate
+    val delegated: Boolean by ::member
     val String.memberExtension: Boolean by Delegate
+    val String.memberExtensionDelegated: Boolean by ::member
 }
 
 inline fun check(block: () -> Unit) {
@@ -29,16 +33,24 @@ inline fun check(block: () -> Unit) {
 
 fun box(): String {
     check { ::topLevel.getDelegate() }
+    check { ::delegated.getDelegate() }
 
     check { String::extension.getDelegate("") }
     check { ""::extension.getDelegate() }
+    check { String::delegated.getDelegate("") }
+    check { ""::delegated.getDelegate() }
 
     val foo = Foo()
     check { Foo::member.getDelegate(foo) }
     check { foo::member.getDelegate() }
+    check { Foo::delegated.getDelegate(foo) }
+    check { foo::delegated.getDelegate() }
 
     val me = Foo::class.members.single { it.name == "memberExtension" } as KProperty2<Foo, String, Boolean>
     check { me.getDelegate(foo, "") }
 
+    val med = Foo::class.members.single { it.name == "memberExtensionDelegated" } as KProperty2<Foo, String, Boolean>
+    check { med.getDelegate(foo, "") }
+
     return "OK"
 }

compiler/testData/codegen/bytecodeListing/delegatedProperty/delegateMethodIsNonOverridable_ir.txt

@@ -16,7 +16,7 @@ public class C {
     inner (anonymous) class C$x$2$1
     public method <init>(): void
     public method getX(): int
-    public static method getY$delegate(p0: C): java.lang.Object
+    private static method getY$delegate(p0: C): java.lang.Object
     public method getY(): int
 }
 
@@ -38,7 +38,7 @@ public final class D {
     inner (anonymous) class D$x$2$1
     public method <init>(): void
     public method getX(): int
-    public static method getY$delegate(p0: D): java.lang.Object
+    private static method getY$delegate(p0: D): java.lang.Object
     public method getY(): int
 }
 

compiler/testData/codegen/bytecodeText/optimizedDelegatedProperties/delegateToAnother.kt

@@ -35,7 +35,7 @@ fun local() {
 // 0 private final( static)? Lkotlin/reflect/KMutableProperty[0-2]; [xyz]m?\$delegate
 // 2 private final( static)? LC; [xyz]m?\$receiver
 // 0 LOCALVARIABLE [xyz]m? Lkotlin/reflect/KMutableProperty[0-2];
-// 12 public( static)? get[XYZ]m?\$delegate
+// 12 private( static)? get[XYZ]m?\$delegate
 
 // JVM_TEMPLATES
 // Not optimized, references created as classes and stored in fields:

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java

@@ -42201,6 +42201,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                     runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegate.kt");
                 }
 
+                @Test
+                @TestMetadata("getExtensionDelegateForDelegatedToAnother.kt")
+                public void testGetExtensionDelegateForDelegatedToAnother() throws Exception {
+                    runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegateForDelegatedToAnother.kt");
+                }
+
                 @Test
                 @TestMetadata("kPropertyForDelegatedProperty.kt")
                 public void testKPropertyForDelegatedProperty() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -42723,6 +42723,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                     runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegate.kt");
                 }
 
+                @Test
+                @TestMetadata("getExtensionDelegateForDelegatedToAnother.kt")
+                public void testGetExtensionDelegateForDelegatedToAnother() throws Exception {
+                    runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegateForDelegatedToAnother.kt");
+                }
+
                 @Test
                 @TestMetadata("kPropertyForDelegatedProperty.kt")
                 public void testKPropertyForDelegatedProperty() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -33942,6 +33942,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                     runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegate.kt");
                 }
 
+                @TestMetadata("getExtensionDelegateForDelegatedToAnother.kt")
+                public void testGetExtensionDelegateForDelegatedToAnother() throws Exception {
+                    runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/getExtensionDelegateForDelegatedToAnother.kt");
+                }
+
                 @TestMetadata("kPropertyForDelegatedProperty.kt")
                 public void testKPropertyForDelegatedProperty() throws Exception {
                     runTest("compiler/testData/codegen/box/reflection/properties/getDelegate/kPropertyForDelegatedProperty.kt");

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KPropertyImpl.kt

@@ -14,10 +14,7 @@ import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.isUnderlyingPropertyOfInlineClass
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedPropertyDescriptor
 import org.jetbrains.kotlin.types.TypeUtils
-import java.lang.reflect.Field
+import java.lang.reflect.*
-import java.lang.reflect.Member
-import java.lang.reflect.Method
-import java.lang.reflect.Modifier
 import kotlin.jvm.internal.CallableReference
 import kotlin.reflect.KFunction
 import kotlin.reflect.KMutableProperty
@@ -25,6 +22,7 @@ import kotlin.reflect.KProperty
 import kotlin.reflect.full.IllegalPropertyDelegateAccessException
 import kotlin.reflect.jvm.internal.JvmPropertySignature.*
 import kotlin.reflect.jvm.internal.calls.*
+import kotlin.reflect.jvm.isAccessible
 
 internal abstract class KPropertyImpl<out V> private constructor(
     override val container: KDeclarationContainerImpl,
@@ -105,6 +103,7 @@ internal abstract class KPropertyImpl<out V> private constructor(
 
             val realReceiver1 = (if (isBound) boundReceiver else receiver1).takeIf { it !== EXTENSION_PROPERTY_DELEGATE }
             val realReceiver2 = (if (isBound) receiver1 else receiver2).takeIf { it !== EXTENSION_PROPERTY_DELEGATE }
+            (fieldOrMethod as? AccessibleObject)?.isAccessible = isAccessible
             when (fieldOrMethod) {
                 null -> null
                 is Field -> fieldOrMethod.get(realReceiver1)