Improve implementation of callable reference superclasses

Previously to use reflection on them, you had to wrap an already created object
with a "Reflection.function" or "Reflection.propertyN" call, which the JVM
back-end was doing. This was not optimal in several senses and current solution
fixes that

compiler/testData/codegen/boxWithStdlib/reflection/methodsFromAny/callableReferencesEqualToCallablesFromAPI.kt

@@ -0,0 +1,20 @@
+import kotlin.reflect.*
+import kotlin.test.assertEquals
+
+class A {
+    fun foo() = "foo"
+    val bar = "bar"
+}
+
+fun checkEqual(x: Any, y: Any) {
+    assertEquals(x, y)
+    assertEquals(y, x)
+    assertEquals(x.hashCode(), y.hashCode())
+}
+
+fun box(): String {
+    checkEqual(A::foo, A::class.members.single { it.name == "foo" })
+    checkEqual(A::bar, A::class.members.single { it.name == "bar" })
+
+    return "OK"
+}

compiler/tests/org/jetbrains/kotlin/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java

@@ -3912,6 +3912,12 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/boxWithStdlib/reflection/methodsFromAny"), Pattern.compile("^(.+)\\.kt$"), true);
             }
 
+            @TestMetadata("callableReferencesEqualToCallablesFromAPI.kt")
+            public void testCallableReferencesEqualToCallablesFromAPI() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reflection/methodsFromAny/callableReferencesEqualToCallablesFromAPI.kt");
+                doTestWithStdlib(fileName);
+            }
+
             @TestMetadata("classToString.kt")
             public void testClassToString() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reflection/methodsFromAny/classToString.kt");

core/reflection.jvm/src/kotlin/reflect/jvm/KCallablesJvm.kt

@@ -22,7 +22,7 @@ import kotlin.reflect.KCallable
 import kotlin.reflect.KFunction
 import kotlin.reflect.KMutableProperty
 import kotlin.reflect.KProperty
-import kotlin.reflect.jvm.internal.KCallableImpl
+import kotlin.reflect.jvm.internal.asKCallableImpl
 
 /**
  * Provides a way to suppress JVM access checks for a callable.
@@ -53,7 +53,7 @@ public var KCallable<*>.isAccessible: Boolean
                 javaMethod?.isAccessible ?: true
             is KFunction ->
                 javaMethod?.isAccessible ?: true &&
-                ((this as? KCallableImpl<*>)?.defaultCaller?.member as? AccessibleObject)?.isAccessible ?: true &&
+                (this.asKCallableImpl()?.defaultCaller?.member as? AccessibleObject)?.isAccessible ?: true &&
                 this.javaConstructor?.isAccessible ?: true
             else -> throw UnsupportedOperationException("Unknown callable: $this ($javaClass)")
         }
@@ -79,7 +79,7 @@ public var KCallable<*>.isAccessible: Boolean
             }
             is KFunction -> {
                 javaMethod?.isAccessible = value
-                ((this as? KCallableImpl<*>)?.defaultCaller?.member as? AccessibleObject)?.isAccessible = true
+                (this.asKCallableImpl()?.defaultCaller?.member as? AccessibleObject)?.isAccessible = true
                 this.javaConstructor?.isAccessible = value
             }
             else -> throw UnsupportedOperationException("Unknown callable: $this ($javaClass)")

core/reflection.jvm/src/kotlin/reflect/jvm/ReflectJvmMapping.kt

@@ -23,8 +23,9 @@ import kotlin.jvm.internal.KotlinFileFacade
 import kotlin.jvm.internal.Reflection
 import kotlin.reflect.*
 import kotlin.reflect.jvm.internal.KCallableImpl
-import kotlin.reflect.jvm.internal.KPropertyImpl
 import kotlin.reflect.jvm.internal.KTypeImpl
+import kotlin.reflect.jvm.internal.asKCallableImpl
+import kotlin.reflect.jvm.internal.asKPropertyImpl
 
 // Kotlin reflection -> Java reflection
 
@@ -33,7 +34,7 @@ import kotlin.reflect.jvm.internal.KTypeImpl
  * or `null` if the property has no backing field.
  */
 public val KProperty<*>.javaField: Field?
-    get() = (this as? KPropertyImpl<*>)?.javaField
+    get() = this.asKPropertyImpl()?.javaField
 
 /**
  * Returns a Java [Method] instance corresponding to the getter of the given property,
@@ -55,7 +56,7 @@ public val KMutableProperty<*>.javaSetter: Method?
  * or `null` if this function is a constructor or cannot be represented by a Java [Method].
  */
 public val KFunction<*>.javaMethod: Method?
-    get() = (this as? KCallableImpl<*>)?.caller?.member as? Method
+    get() = this.asKCallableImpl()?.caller?.member as? Method
 
 /**
  * Returns a Java [Constructor] instance corresponding to the given Kotlin function,
@@ -63,7 +64,7 @@ public val KFunction<*>.javaMethod: Method?
  */
 @Suppress("UNCHECKED_CAST")
 public val <T> KFunction<T>.javaConstructor: Constructor<T>?
-    get() = (this as? KCallableImpl<T>)?.caller?.member as? Constructor<T>
+    get() = this.asKCallableImpl()?.caller?.member as? Constructor<T>
 
 
 /**

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

@@ -19,13 +19,14 @@ package kotlin.reflect.jvm.internal
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.serialization.jvm.JvmProtoBufUtil
 import java.lang.reflect.Field
+import kotlin.reflect.KProperty
 import kotlin.reflect.jvm.internal.JvmPropertySignature.JavaField
 import kotlin.reflect.jvm.internal.JvmPropertySignature.KotlinProperty
 
 internal abstract class DescriptorBasedProperty<out R> protected constructor(
         val container: KDeclarationContainerImpl,
         name: String,
-        signature: String,
+        val signature: String,
         descriptorInitialValue: PropertyDescriptor?
 ) : KCallableImpl<R> {
     constructor(container: KDeclarationContainerImpl, name: String, signature: String) : this(
@@ -55,11 +56,13 @@ internal abstract class DescriptorBasedProperty<out R> protected constructor(
         }
     }
 
-    override fun equals(other: Any?): Boolean =
+    override fun equals(other: Any?): Boolean {
-            other is DescriptorBasedProperty<*> && descriptor == other.descriptor
+        val that = other.asKPropertyImpl() ?: return false
+        return container == that.container && name == that.name && signature == that.signature
+    }
 
     override fun hashCode(): Int =
-            descriptor.hashCode()
+            (container.hashCode() * 31 + name.hashCode()) * 31 + signature.hashCode()
 
     override fun toString(): String =
             ReflectionObjectRenderer.renderProperty(descriptor)

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

@@ -30,7 +30,7 @@ import kotlin.reflect.jvm.internal.JvmFunctionSignature.*
 internal open class KFunctionImpl protected constructor(
         private val container: KDeclarationContainerImpl,
         name: String,
-        signature: String,
+        private val signature: String,
         descriptorInitialValue: FunctionDescriptor?
 ) : KFunction<Any?>, KCallableImpl<Any?>, FunctionImpl() {
     constructor(container: KDeclarationContainerImpl, name: String, signature: String) : this(container, name, signature, null)
@@ -104,11 +104,13 @@ internal open class KFunctionImpl protected constructor(
                (if (descriptor.extensionReceiverParameter != null) 1 else 0)
     }
 
-    override fun equals(other: Any?): Boolean =
+    override fun equals(other: Any?): Boolean {
-            other is KFunctionImpl && descriptor == other.descriptor
+        val that = other.asKFunctionImpl() ?: return false
+        return container == that.container && name == that.name && signature == that.signature
+    }
 
     override fun hashCode(): Int =
-            descriptor.hashCode()
+            (container.hashCode() * 31 + name.hashCode()) * 31 + signature.hashCode()
 
     override fun toString(): String =
             ReflectionObjectRenderer.renderFunction(descriptor)

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

@@ -33,6 +33,8 @@ internal interface KPropertyImpl<out R> : KProperty<R>, KCallableImpl<R> {
 
     val container: KDeclarationContainerImpl
 
+    val signature: String
+
     override val getter: Getter<R>
 
     override val descriptor: PropertyDescriptor

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

@@ -17,6 +17,8 @@
 package kotlin.reflect.jvm.internal
 
 import org.jetbrains.kotlin.name.FqName
+import kotlin.jvm.internal.FunctionReference
+import kotlin.jvm.internal.PropertyReference
 import kotlin.reflect.IllegalCallableAccessException
 
 internal val JVM_STATIC = FqName("kotlin.jvm.JvmStatic")
@@ -29,3 +31,14 @@ internal inline fun <R> reflectionCall(block: () -> R): R =
         catch (e: IllegalAccessException) {
             throw IllegalCallableAccessException(e)
         }
+
+internal fun Any?.asKFunctionImpl(): KFunctionImpl? =
+        this as? KFunctionImpl ?:
+        (this as? FunctionReference)?.compute() as? KFunctionImpl //
+
+internal fun Any?.asKPropertyImpl(): KPropertyImpl<*>? =
+        this as? KPropertyImpl<*> ?:
+        (this as? PropertyReference)?.compute() as? KPropertyImpl
+
+internal fun Any?.asKCallableImpl(): KCallableImpl<*>? =
+        this as? KCallableImpl<*> ?: asKFunctionImpl() ?: asKPropertyImpl()

core/runtime.jvm/src/kotlin/jvm/internal/CallableReference.java

@@ -17,10 +17,7 @@
 package kotlin.jvm.internal;
 
 import kotlin.jvm.KotlinReflectionNotSupportedError;
-import kotlin.reflect.KCallable;
+import kotlin.reflect.*;
-import kotlin.reflect.KDeclarationContainer;
-import kotlin.reflect.KParameter;
-import kotlin.reflect.KType;
 import org.jetbrains.annotations.NotNull;
 
 import java.lang.annotation.Annotation;
@@ -32,7 +29,11 @@ import java.util.Map;
  *
  * All methods from reflection API should be implemented here to throw informative exceptions (see KotlinReflectionNotSupportedError)
  */
+@SuppressWarnings({"unchecked", "NullableProblems"})
 public abstract class CallableReference implements KCallable {
+    protected KCallable reflected;
+
+    protected abstract KCallable computeReflected();
 
     // The following methods provide the information identifying this callable, which is used by the reflection implementation.
     // They are supposed to be overridden in each subclass (each anonymous class generated for a callable reference).
@@ -41,7 +42,7 @@ public abstract class CallableReference implements KCallable {
      * @return the class or package where the callable should be located, usually specified on the LHS of the '::' operator
      */
     public KDeclarationContainer getOwner() {
-        throw error();
+        throw new AbstractMethodError();
     }
 
     /**
@@ -49,7 +50,7 @@ public abstract class CallableReference implements KCallable {
      */
     @Override
     public String getName() {
-        throw error();
+        throw new AbstractMethodError();
     }
 
     /**
@@ -61,7 +62,7 @@ public abstract class CallableReference implements KCallable {
      * but only as a unique and unambiguous way to map a function/property descriptor to a string.
      */
     public String getSignature() {
-        throw error();
+        throw new AbstractMethodError();
     }
 
     // The following methods are the stub implementations of reflection functions.
@@ -69,30 +70,41 @@ public abstract class CallableReference implements KCallable {
 
     @Override
     public List<KParameter> getParameters() {
-        throw error();
+        return getReflected().getParameters();
     }
 
     @Override
     public KType getReturnType() {
-        throw error();
+        return getReflected().getReturnType();
     }
 
     @Override
     public List<Annotation> getAnnotations() {
-        throw error();
+        return getReflected().getAnnotations();
     }
 
     @Override
     public Object call(@NotNull Object... args) {
-        throw error();
+        return getReflected().call(args);
     }
 
     @Override
     public Object callBy(@NotNull Map args) {
-        throw error();
+        return getReflected().callBy(args);
     }
 
-    protected static Error error() {
+    public KCallable compute() {
-        throw new KotlinReflectionNotSupportedError();
+        if (reflected == null) {
+            reflected = computeReflected();
+        }
+        return reflected;
+    }
+
+    protected KCallable getReflected() {
+        compute();
+        if (reflected == this) {
+            throw new KotlinReflectionNotSupportedError();
+        }
+        return reflected;
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/FunctionReference.java

@@ -17,15 +17,20 @@
 package kotlin.jvm.internal;
 
 import kotlin.jvm.KotlinReflectionNotSupportedError;
-import kotlin.reflect.*;
+import kotlin.reflect.KDeclarationContainer;
+import kotlin.reflect.KFunction;
+import kotlin.reflect.KParameter;
+import kotlin.reflect.KType;
 import org.jetbrains.annotations.NotNull;
 
 import java.lang.annotation.Annotation;
 import java.util.List;
 import java.util.Map;
 
+@SuppressWarnings({"unchecked", "NullableProblems"})
 public class FunctionReference extends FunctionImpl implements KFunction {
     private final int arity;
+    private KFunction reflected;
 
     public FunctionReference(int arity) {
         this.arity = arity;
@@ -39,56 +44,57 @@ public class FunctionReference extends FunctionImpl implements KFunction {
     // Most of the following methods are copies from CallableReference, since this class cannot inherit from it
 
     public KDeclarationContainer getOwner() {
-        throw error();
+        throw new AbstractMethodError();
     }
 
     @Override
     public String getName() {
-        throw error();
+        throw new AbstractMethodError();
     }
 
     public String getSignature() {
-        throw error();
+        throw new AbstractMethodError();
     }
 
     @Override
     public List<KParameter> getParameters() {
-        throw error();
+        return getReflected().getParameters();
     }
 
     @Override
     public KType getReturnType() {
-        throw error();
+        return getReflected().getReturnType();
     }
 
     @Override
     public List<Annotation> getAnnotations() {
-        throw error();
+        return getReflected().getAnnotations();
     }
 
     @Override
     public Object call(@NotNull Object... args) {
-        throw error();
+        return getReflected().call(args);
     }
 
     @Override
     public Object callBy(@NotNull Map args) {
-        throw error();
+        return getReflected().callBy(args);
-    }
-
-    protected static Error error() {
-        throw new KotlinReflectionNotSupportedError();
     }
 
     @Override
     public boolean equals(Object obj) {
         if (obj == this) return true;
-        if (!(obj instanceof FunctionReference)) return false;
+        if (obj instanceof FunctionReference) {
-
+            FunctionReference other = (FunctionReference) obj;
-        FunctionReference other = (FunctionReference) obj;
+            return getOwner().equals(other.getOwner()) &&
-        return getOwner().equals(other.getOwner()) &&
+                   getName().equals(other.getName()) &&
-               getName().equals(other.getName()) &&
+                   getSignature().equals(other.getSignature());
-               getSignature().equals(other.getSignature());
+        }
+        if (obj instanceof KFunction) {
+            compute();
+            return obj.equals(reflected);
+        }
+        return false;
     }
 
     @Override
@@ -98,9 +104,29 @@ public class FunctionReference extends FunctionImpl implements KFunction {
 
     @Override
     public String toString() {
+        compute();
+        if (reflected != this) {
+            return reflected.toString();
+        }
+
         // TODO: consider adding the class name to toString() for constructors
         return "<init>".equals(getName())
                ? "constructor" + Reflection.REFLECTION_NOT_AVAILABLE
                : "function " + getName() + Reflection.REFLECTION_NOT_AVAILABLE;
     }
+
+    public KFunction compute() {
+        if (reflected == null) {
+            reflected = Reflection.function(this);
+        }
+        return reflected;
+    }
+
+    private KFunction getReflected() {
+        compute();
+        if (reflected == this) {
+            throw new KotlinReflectionNotSupportedError();
+        }
+        return reflected;
+    }
 }

core/runtime.jvm/src/kotlin/jvm/internal/MutablePropertyReference0.java

@@ -16,27 +16,33 @@
 
 package kotlin.jvm.internal;
 
+import kotlin.reflect.KCallable;
 import kotlin.reflect.KMutableProperty0;
 import kotlin.reflect.KProperty0;
 
 public class MutablePropertyReference0 extends MutablePropertyReference implements KMutableProperty0 {
+    @Override
+    protected KCallable computeReflected() {
+        return Reflection.mutableProperty0(this);
+    }
+
     @Override
     public Object get() {
-        throw error();
+        return ((KMutableProperty0) getReflected()).get();
     }
 
     @Override
     public void set(Object value) {
-        throw error();
+        ((KMutableProperty0) getReflected()).set(value);
     }
 
     @Override
     public KProperty0.Getter getGetter() {
-        throw error();
+        return ((KMutableProperty0) getReflected()).getGetter();
     }
 
     @Override
     public KMutableProperty0.Setter getSetter() {
-        throw error();
+        return ((KMutableProperty0) getReflected()).getSetter();
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/MutablePropertyReference1.java

@@ -16,27 +16,33 @@
 
 package kotlin.jvm.internal;
 
+import kotlin.reflect.KCallable;
 import kotlin.reflect.KMutableProperty1;
 import kotlin.reflect.KProperty1;
 
 public class MutablePropertyReference1 extends MutablePropertyReference implements KMutableProperty1 {
+    @Override
+    protected KCallable computeReflected() {
+        return Reflection.mutableProperty1(this);
+    }
+
     @Override
     public Object get(Object receiver) {
-        throw error();
+        return ((KMutableProperty1) getReflected()).get(receiver);
     }
 
     @Override
     public void set(Object receiver, Object value) {
-        throw error();
+        ((KMutableProperty1) getReflected()).set(receiver, value);
     }
 
     @Override
     public KProperty1.Getter getGetter() {
-        throw error();
+        return ((KMutableProperty1) getReflected()).getGetter();
     }
 
     @Override
     public KMutableProperty1.Setter getSetter() {
-        throw error();
+        return ((KMutableProperty1) getReflected()).getSetter();
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/MutablePropertyReference2.java

@@ -16,27 +16,33 @@
 
 package kotlin.jvm.internal;
 
+import kotlin.reflect.KCallable;
 import kotlin.reflect.KMutableProperty2;
 import kotlin.reflect.KProperty2;
 
 public class MutablePropertyReference2 extends MutablePropertyReference implements KMutableProperty2 {
+    @Override
+    protected KCallable computeReflected() {
+        return Reflection.mutableProperty2(this);
+    }
+
     @Override
     public Object get(Object receiver1, Object receiver2) {
-        throw error();
+        return ((KMutableProperty2) getReflected()).get(receiver1, receiver2);
     }
 
     @Override
     public void set(Object receiver1, Object receiver2, Object value) {
-        throw error();
+        ((KMutableProperty2) getReflected()).set(receiver1, receiver2, value);
     }
 
     @Override
     public KProperty2.Getter getGetter() {
-        throw error();
+        return ((KMutableProperty2) getReflected()).getGetter();
     }
 
     @Override
     public KMutableProperty2.Setter getSetter() {
-        throw error();
+        return ((KMutableProperty2) getReflected()).getSetter();
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/PropertyReference.java

@@ -22,12 +22,17 @@ public abstract class PropertyReference extends CallableReference implements KPr
     @Override
     public boolean equals(Object obj) {
         if (obj == this) return true;
-        if (!(obj instanceof PropertyReference)) return false;
+        if (obj instanceof PropertyReference) {
-
+            PropertyReference other = (PropertyReference) obj;
-        PropertyReference other = (PropertyReference) obj;
+            return getOwner().equals(other.getOwner()) &&
-        return getOwner().equals(other.getOwner()) &&
+                   getName().equals(other.getName()) &&
-               getName().equals(other.getName()) &&
+                   getSignature().equals(other.getSignature());
-               getSignature().equals(other.getSignature());
+        }
+        if (obj instanceof KProperty) {
+            compute();
+            return obj.equals(reflected);
+        }
+        return false;
     }
 
     @Override
@@ -37,6 +42,11 @@ public abstract class PropertyReference extends CallableReference implements KPr
 
     @Override
     public String toString() {
+        compute();
+        if (reflected != this) {
+            return reflected.toString();
+        }
+
         return "property " + getName() + Reflection.REFLECTION_NOT_AVAILABLE;
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/PropertyReference0.java

@@ -16,16 +16,22 @@
 
 package kotlin.jvm.internal;
 
+import kotlin.reflect.KCallable;
 import kotlin.reflect.KProperty0;
 
 public class PropertyReference0 extends PropertyReference implements KProperty0 {
+    @Override
+    protected KCallable computeReflected() {
+        return Reflection.property0(this);
+    }
+
     @Override
     public Object get() {
-        throw error();
+        return ((KProperty0) getReflected()).get();
     }
 
     @Override
     public KProperty0.Getter getGetter() {
-        throw error();
+        return ((KProperty0) getReflected()).getGetter();
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/PropertyReference1.java

@@ -16,16 +16,22 @@
 
 package kotlin.jvm.internal;
 
+import kotlin.reflect.KCallable;
 import kotlin.reflect.KProperty1;
 
 public class PropertyReference1 extends PropertyReference implements KProperty1 {
+    @Override
+    protected KCallable computeReflected() {
+        return Reflection.property1(this);
+    }
+
     @Override
     public Object get(Object receiver) {
-        throw error();
+        return ((KProperty1) getReflected()).get(receiver);
     }
 
     @Override
     public KProperty1.Getter getGetter() {
-        throw error();
+        return ((KProperty1) getReflected()).getGetter();
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/PropertyReference2.java

@@ -16,16 +16,22 @@
 
 package kotlin.jvm.internal;
 
+import kotlin.reflect.KCallable;
 import kotlin.reflect.KProperty2;
 
 public class PropertyReference2 extends PropertyReference implements KProperty2 {
+    @Override
+    protected KCallable computeReflected() {
+        return Reflection.property2(this);
+    }
+
     @Override
     public Object get(Object receiver1, Object receiver2) {
-        throw error();
+        return ((KProperty2) getReflected()).get(receiver1, receiver2);
     }
 
     @Override
     public KProperty2.Getter getGetter() {
-        throw error();
+        return ((KProperty2) getReflected()).getGetter();
     }
 }