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

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.KDeclarationContainer;
-import kotlin.reflect.KParameter;
-import kotlin.reflect.KType;
+import kotlin.reflect.*;
 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() {
-        throw new KotlinReflectionNotSupportedError();
+    public KCallable compute() {
+        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();
-    }
-
-    protected static Error error() {
-        throw new KotlinReflectionNotSupportedError();
+        return getReflected().callBy(args);
     }
 
     @Override
     public boolean equals(Object obj) {
         if (obj == this) return true;
-        if (!(obj instanceof FunctionReference)) return false;
-
-        FunctionReference other = (FunctionReference) obj;
-        return getOwner().equals(other.getOwner()) &&
-               getName().equals(other.getName()) &&
-               getSignature().equals(other.getSignature());
+        if (obj instanceof FunctionReference) {
+            FunctionReference other = (FunctionReference) obj;
+            return getOwner().equals(other.getOwner()) &&
+                   getName().equals(other.getName()) &&
+                   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;
-
-        PropertyReference other = (PropertyReference) obj;
-        return getOwner().equals(other.getOwner()) &&
-               getName().equals(other.getName()) &&
-               getSignature().equals(other.getSignature());
+        if (obj instanceof PropertyReference) {
+            PropertyReference other = (PropertyReference) obj;
+            return getOwner().equals(other.getOwner()) &&
+                   getName().equals(other.getName()) &&
+                   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();
     }
 }