Inherit KProperty interfaces from function types

To be able to write the following: listOfStrings.map(String::length)

core/builtins/src/kotlin/reflect/KProperty.kt

@@ -65,7 +65,7 @@ public interface KMutableProperty<R> : KProperty<R> {
  * Such property is either originally declared in a receiverless context such as a package,
  * or has the receiver bound to it.
  */
-public interface KProperty0<out R> : KProperty<R> {
+public interface KProperty0<out R> : KProperty<R>, () -> R {
     /**
      * Returns the current value of the property.
      */
@@ -99,7 +99,7 @@ public interface KMutableProperty0<R> : KProperty0<R>, KMutableProperty<R> {
  * @param T the type of the receiver which should be used to obtain the value of the property.
  * @param R the type of the property.
  */
-public interface KProperty1<T, out R> : KProperty<R> {
+public interface KProperty1<T, out R> : KProperty<R>, (T) -> R {
     /**
      * Returns the current value of the property.
      *
@@ -144,7 +144,7 @@ public interface KMutableProperty1<T, R> : KProperty1<T, R>, KMutableProperty<R>
  *        the type of the extension receiver.
  * @param R the type of the property.
  */
-public interface KProperty2<D, E, out R> : KProperty<R> {
+public interface KProperty2<D, E, out R> : KProperty<R>, (D, E) -> R {
     /**
      * Returns the current value of the property. In case of the extension property in a class,
      * the instance of the class should be passed first and the instance of the extension receiver second.

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KProperty0Impl.kt

@@ -31,6 +31,8 @@ internal open class KProperty0Impl<out R> : DescriptorBasedProperty<R>, KPropert
 
     override fun get(): R = getter.call()
 
+    override fun invoke(): R = get()
+
     class Getter<out R>(override val property: KProperty0Impl<R>) : KPropertyImpl.Getter<R>(), KProperty0.Getter<R> {
         override fun invoke(): R = property.get()
     }

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KProperty1Impl.kt

@@ -31,6 +31,8 @@ internal open class KProperty1Impl<T, out R> : DescriptorBasedProperty<R>, KProp
 
     override fun get(receiver: T): R = getter.call(receiver)
 
+    override fun invoke(receiver: T): R = get(receiver)
+
     class Getter<T, out R>(override val property: KProperty1Impl<T, R>) : KPropertyImpl.Getter<R>(), KProperty1.Getter<T, R> {
         override fun invoke(receiver: T): R = property.get(receiver)
     }

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KProperty2Impl.kt

@@ -31,6 +31,8 @@ internal open class KProperty2Impl<D, E, out R> : DescriptorBasedProperty<R>, KP
 
     override fun get(receiver1: D, receiver2: E): R = getter.call(receiver1, receiver2)
 
+    override fun invoke(receiver1: D, receiver2: E): R = get(receiver1, receiver2)
+
     class Getter<D, E, out R>(override val property: KProperty2Impl<D, E, R>) : KPropertyImpl.Getter<R>(), KProperty2.Getter<D, E, R> {
         override fun invoke(receiver1: D, receiver2: E): R = property.get(receiver1, receiver2)
     }

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

@@ -36,6 +36,11 @@ public class MutablePropertyReference0 extends MutablePropertyReference implemen
         ((KMutableProperty0) getReflected()).set(value);
     }
 
+    @Override
+    public Object invoke() {
+        return get();
+    }
+
     @Override
     public KProperty0.Getter getGetter() {
         return ((KMutableProperty0) getReflected()).getGetter();

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

@@ -36,6 +36,11 @@ public class MutablePropertyReference1 extends MutablePropertyReference implemen
         ((KMutableProperty1) getReflected()).set(receiver, value);
     }
 
+    @Override
+    public Object invoke(Object receiver) {
+        return get(receiver);
+    }
+
     @Override
     public KProperty1.Getter getGetter() {
         return ((KMutableProperty1) getReflected()).getGetter();

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

@@ -36,6 +36,11 @@ public class MutablePropertyReference2 extends MutablePropertyReference implemen
         ((KMutableProperty2) getReflected()).set(receiver1, receiver2, value);
     }
 
+    @Override
+    public Object invoke(Object receiver1, Object receiver2) {
+        return get(receiver1, receiver2);
+    }
+
     @Override
     public KProperty2.Getter getGetter() {
         return ((KMutableProperty2) getReflected()).getGetter();

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

@@ -30,6 +30,11 @@ public class PropertyReference0 extends PropertyReference implements KProperty0
         return ((KProperty0) getReflected()).get();
     }
 
+    @Override
+    public Object invoke() {
+        return get();
+    }
+
     @Override
     public KProperty0.Getter getGetter() {
         return ((KProperty0) getReflected()).getGetter();

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

@@ -30,6 +30,11 @@ public class PropertyReference1 extends PropertyReference implements KProperty1
         return ((KProperty1) getReflected()).get(receiver);
     }
 
+    @Override
+    public Object invoke(Object receiver) {
+        return get(receiver);
+    }
+
     @Override
     public KProperty1.Getter getGetter() {
         return ((KProperty1) getReflected()).getGetter();

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

@@ -30,6 +30,11 @@ public class PropertyReference2 extends PropertyReference implements KProperty2
         return ((KProperty2) getReflected()).get(receiver1, receiver2);
     }
 
+    @Override
+    public Object invoke(Object receiver1, Object receiver2) {
+        return get(receiver1, receiver2);
+    }
+
     @Override
     public KProperty2.Getter getGetter() {
         return ((KProperty2) getReflected()).getGetter();