Implement KClass.getProperties()

#KT-6570 In Progress

compiler/testData/codegen/boxWithStdlib/reflection/properties/callPrivatePropertyFromGetProperties.kt

@@ -0,0 +1,19 @@
+import kotlin.reflect.*
+import kotlin.reflect.jvm.*
+
+class K(private val value: String)
+
+fun box(): String {
+    val p = javaClass<K>().kotlin.getProperties().single() as KMemberProperty<K, String>
+
+    try {
+        return p.get(K("Fail: private property should not be accessible by default"))
+    }
+    catch (e: IllegalPropertyAccessException) {
+        // OK
+    }
+
+    p.accessible = true
+
+    return p.get(K("OK"))
+}

compiler/testData/codegen/boxWithStdlib/reflection/properties/fakeOverridesInSubclass.kt

@@ -0,0 +1,12 @@
+import kotlin.reflect.jvm.*
+import kotlin.test.*
+
+open class Super(val r: String)
+
+class Sub(r: String) : Super(r)
+
+fun box(): String {
+    val props = javaClass<Sub>().kotlin.getProperties()
+    assertEquals(listOf("r"), props.map { it.name })
+    return props.single().get(Sub("OK")).toString()
+}

compiler/testData/codegen/boxWithStdlib/reflection/properties/getPropertiesMutableVsReadonly.kt

@@ -0,0 +1,20 @@
+import kotlin.reflect.jvm.kotlin
+import kotlin.reflect.KMutableMemberProperty
+
+class A(val readonly: String) {
+    var mutable: String = "before"
+}
+
+fun box(): String {
+    val props = javaClass<A>().kotlin.getProperties()
+    val readonly = props.single { it.name == "readonly" }
+    assert(readonly !is KMutableMemberProperty<A, *>) { "Fail 1: $readonly" }
+    val mutable = props.single { it.name == "mutable" }
+    assert(mutable is KMutableMemberProperty<A, *>) { "Fail 2: $mutable" }
+
+    val a = A("")
+    mutable as KMutableMemberProperty<A, String>
+    assert(mutable[a] == "before") { "Fail 3: ${mutable.get(a)}" }
+    mutable[a] = "OK"
+    return mutable.get(a)
+}

compiler/testData/codegen/boxWithStdlib/reflection/properties/simpleGetProperties.kt

@@ -0,0 +1,23 @@
+import kotlin.reflect.jvm.kotlin
+
+class A(param: String) {
+    val int: Int get() = 42
+    val string: String = param
+    var anyVar: Any? = null
+
+    val List<IntRange>.extensionToList: Unit get() {}
+
+    fun notAProperty() {}
+}
+
+fun box(): String {
+    val klass = javaClass<A>().kotlin
+
+    val props = klass.getProperties()
+
+    val names = props.map { it.name }.toSortedList()
+    assert(names == listOf("anyVar", "int", "string")) { "Fail names: $props" }
+
+    val stringProp = props.firstOrNull { it.name == "string" } ?: return "Fail, string not found: $props"
+    return stringProp.get(A("OK")) as String
+}

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

@@ -2528,6 +2528,7 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
             Reflection.GenericSignature.class,
             Reflection.Mapping.class,
             Reflection.MethodsFromAny.class,
+            Reflection.Properties.class,
     })
     @RunWith(JUnit3RunnerWithInners.class)
     public static class Reflection extends AbstractBlackBoxCodegenTest {
@@ -2780,6 +2781,39 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
                 doTestWithStdlib(fileName);
             }
         }
+
+        @TestMetadata("compiler/testData/codegen/boxWithStdlib/reflection/properties")
+        @TestDataPath("$PROJECT_ROOT")
+        @RunWith(JUnit3RunnerWithInners.class)
+        public static class Properties extends AbstractBlackBoxCodegenTest {
+            public void testAllFilesPresentInProperties() throws Exception {
+                JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/boxWithStdlib/reflection/properties"), Pattern.compile("^(.+)\\.kt$"), true);
+            }
+
+            @TestMetadata("callPrivatePropertyFromGetProperties.kt")
+            public void testCallPrivatePropertyFromGetProperties() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reflection/properties/callPrivatePropertyFromGetProperties.kt");
+                doTestWithStdlib(fileName);
+            }
+
+            @TestMetadata("fakeOverridesInSubclass.kt")
+            public void testFakeOverridesInSubclass() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reflection/properties/fakeOverridesInSubclass.kt");
+                doTestWithStdlib(fileName);
+            }
+
+            @TestMetadata("getPropertiesMutableVsReadonly.kt")
+            public void testGetPropertiesMutableVsReadonly() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reflection/properties/getPropertiesMutableVsReadonly.kt");
+                doTestWithStdlib(fileName);
+            }
+
+            @TestMetadata("simpleGetProperties.kt")
+            public void testSimpleGetProperties() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reflection/properties/simpleGetProperties.kt");
+                doTestWithStdlib(fileName);
+            }
+        }
     }
 
     @TestMetadata("compiler/testData/codegen/boxWithStdlib/regressions")

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

@@ -16,6 +16,7 @@
 
 package kotlin.reflect.jvm.internal
 
+import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.resolve.scopes.JetScope
 import org.jetbrains.kotlin.serialization.deserialization.findClassAcrossModuleDependencies
 import kotlin.reflect.KClass
@@ -40,6 +41,19 @@ class KClassImpl<T>(override val jClass: Class<T>) : KCallableContainerImpl(), K
 
     override val scope: JetScope get() = descriptor.getDefaultType().getMemberScope()
 
+    override fun getProperties(): Collection<KMemberProperty<T, *>> {
+        return scope.getAllDescriptors().stream()
+                .filterIsInstance<PropertyDescriptor>()
+                .filter { descriptor ->
+                    descriptor.getExtensionReceiverParameter() == null
+                }
+                .map { descriptor ->
+                    if (descriptor.isVar()) KMutableMemberPropertyImpl<T, Any?>(this) { descriptor }
+                    else KMemberPropertyImpl<T, Any?>(this) { descriptor }
+                }
+                .toList()
+    }
+
     fun memberProperty(name: String): KMemberProperty<T, *> {
         return KMemberPropertyImpl<T, Any>(this, findPropertyDescriptor(name))
     }

core/reflection/src/kotlin/reflect/KClass.kt

@@ -16,4 +16,6 @@
 
 package kotlin.reflect
 
-public trait KClass<out T>
+public trait KClass<T> {
+    public fun getProperties(): Collection<KMemberProperty<T, *>>
+}