Support KClass.isInstance/cast/safeCast in stdlib-only reflection implementation

#KT-14720 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/checkers/AbstractReflectionApiCallChecker.kt

@@ -48,7 +48,7 @@ abstract class AbstractReflectionApiCallChecker(
     private val kClass by storageManager.createLazyValue { reflectionTypes.kClass }
 
     protected open fun isAllowedKClassMember(name: Name): Boolean =
-        name.asString() == "simpleName"
+        name.asString() == "simpleName" || name.asString() == "isInstance"
 
     final override fun check(resolvedCall: ResolvedCall<*>, reportOn: PsiElement, context: CallCheckerContext) {
         if (isWholeReflectionApiAvailable) return

compiler/testData/codegen/box/reflection/isInstance/isInstanceCastAndSafeCast.kt

@@ -1,10 +1,10 @@
+// !USE_EXPERIMENTAL: kotlin.ExperimentalStdlibApi
 // TARGET_BACKEND: JVM
-
-// WITH_REFLECT
+// WITH_RUNTIME
 
 import kotlin.reflect.KClass
-import kotlin.reflect.full.cast
-import kotlin.reflect.full.safeCast
+import kotlin.reflect.cast
+import kotlin.reflect.safeCast
 import kotlin.test.*
 
 fun testInstance(value: Any?, klass: KClass<*>) {

compiler/testData/diagnostics/tests/reflection/noReflectionInClassPath.kt

@@ -39,6 +39,7 @@ fun <T : Any> kclass(k: KClass<*>, kt: KClass<T>) {
     k.<!NO_REFLECTION_IN_CLASS_PATH!>isCompanion<!>
 
     k.<!NO_REFLECTION_IN_CLASS_PATH!>annotations<!>
+    k.isInstance(42)
 
     k == kt
     k.hashCode()

core/descriptors.runtime/src/org/jetbrains/kotlin/descriptors/runtime/structure/reflectClassUtil.kt

@@ -40,18 +40,6 @@ val Class<*>.primitiveByWrapper: Class<*>?
 val Class<*>.wrapperByPrimitive: Class<*>?
     get() = PRIMITIVE_TO_WRAPPER[this]
 
-private val FUNCTION_CLASSES =
-    listOf(
-        Function0::class.java, Function1::class.java, Function2::class.java, Function3::class.java, Function4::class.java,
-        Function5::class.java, Function6::class.java, Function7::class.java, Function8::class.java, Function9::class.java,
-        Function10::class.java, Function11::class.java, Function12::class.java, Function13::class.java, Function14::class.java,
-        Function15::class.java, Function16::class.java, Function17::class.java, Function18::class.java, Function19::class.java,
-        Function20::class.java, Function21::class.java, Function22::class.java
-    ).mapIndexed { i, clazz -> clazz to i }.toMap()
-
-val Class<*>.functionClassArity: Int?
-    get() = FUNCTION_CLASSES[this]
-
 /**
  * NOTE: does not perform a Java -> Kotlin mapping. If this is not expected, consider using KClassImpl#classId instead
  */

core/reflection.jvm/src/kotlin/reflect/full/KClasses.kt

@@ -24,11 +24,8 @@ import org.jetbrains.kotlin.types.TypeSubstitutor
 import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlin.utils.DFS
 import kotlin.reflect.*
-import kotlin.reflect.jvm.internal.KCallableImpl
-import kotlin.reflect.jvm.internal.KClassImpl
-import kotlin.reflect.jvm.internal.KFunctionImpl
-import kotlin.reflect.jvm.internal.KTypeImpl
-import kotlin.reflect.jvm.internal.KotlinReflectionInternalError
+import kotlin.reflect.jvm.internal.*
+import kotlin.reflect.safeCast as commonSafeCast
 
 /**
  * Returns the primary constructor of this class, or `null` if this class has no primary constructor.
@@ -253,6 +250,7 @@ fun KClass<*>.isSuperclassOf(derived: KClass<*>): Boolean =
  */
 @SinceKotlin("1.1")
 fun <T : Any> KClass<T>.cast(value: Any?): T {
+    // Note: can't use kotlin.reflect.cast because it throws ClassCastException.
     if (!isInstance(value)) throw TypeCastException("Value cannot be cast to $qualifiedName")
     return value as T
 }
@@ -265,9 +263,9 @@ fun <T : Any> KClass<T>.cast(value: Any?): T {
  * @see [KClass.cast]
  */
 @SinceKotlin("1.1")
-fun <T : Any> KClass<T>.safeCast(value: Any?): T? {
-    return if (isInstance(value)) value as T else null
-}
+fun <T : Any> KClass<T>.safeCast(value: Any?): T? =
+    @UseExperimental(ExperimentalStdlibApi::class)
+    commonSafeCast(value)
 
 
 /**

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

@@ -20,8 +20,6 @@ import org.jetbrains.kotlin.builtins.CompanionObjectMapping
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.runtime.components.ReflectKotlinClass
-import org.jetbrains.kotlin.descriptors.runtime.structure.functionClassArity
-import org.jetbrains.kotlin.descriptors.runtime.structure.wrapperByPrimitive
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.load.java.JvmAbi
 import org.jetbrains.kotlin.load.kotlin.header.KotlinClassHeader
@@ -36,7 +34,6 @@ import org.jetbrains.kotlin.serialization.deserialization.MemberDeserializer
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedClassDescriptor
 import org.jetbrains.kotlin.utils.compact
 import kotlin.jvm.internal.ClassReference
-import kotlin.jvm.internal.TypeIntrinsics
 import kotlin.reflect.*
 import kotlin.reflect.jvm.internal.KDeclarationContainerImpl.MemberBelonginess.DECLARED
 import kotlin.reflect.jvm.internal.KDeclarationContainerImpl.MemberBelonginess.INHERITED
@@ -218,13 +215,7 @@ internal class KClassImpl<T : Any>(override val jClass: Class<T>) : KDeclaration
 
     override val objectInstance: T? get() = data().objectInstance
 
-    override fun isInstance(value: Any?): Boolean {
-        // TODO: use Kotlin semantics for mutable/read-only collections once KT-11754 is supported (see TypeIntrinsics)
-        jClass.functionClassArity?.let { arity ->
-            return TypeIntrinsics.isFunctionOfArity(value, arity)
-        }
-        return (jClass.wrapperByPrimitive ?: jClass).isInstance(value)
-    }
+    override fun isInstance(value: Any?): Boolean = ClassReference.isInstance(value, jClass)
 
     override val typeParameters: List<KTypeParameter> get() = data().typeParameters
 

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsReflectionAPICallChecker.kt

@@ -22,7 +22,6 @@ import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.diagnostics.Errors.UNSUPPORTED
 import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.checkers.AbstractReflectionApiCallChecker
 import org.jetbrains.kotlin.resolve.calls.checkers.CallCheckerContext
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
@@ -39,9 +38,6 @@ class JsReflectionAPICallChecker(
     reflectionTypes: ReflectionTypes,
     storageManager: StorageManager
 ) : AbstractReflectionApiCallChecker(reflectionTypes, storageManager) {
-    override fun isAllowedKClassMember(name: Name): Boolean =
-        super.isAllowedKClassMember(name) || name.asString() == "isInstance"
-
     override val isWholeReflectionApiAvailable: Boolean
         get() = false
 

libraries/stdlib/jvm/runtime/kotlin/jvm/internal/ClassReference.kt

@@ -30,7 +30,8 @@ public class ClassReference(override val jClass: Class<*>) : KClass<Any>, ClassB
         get() = error()
 
     @SinceKotlin("1.1")
-    override fun isInstance(value: Any?): Boolean = error()
+    override fun isInstance(value: Any?): Boolean =
+        isInstance(value, jClass)
 
     @SinceKotlin("1.1")
     override val typeParameters: List<KTypeParameter>
@@ -88,6 +89,15 @@ public class ClassReference(override val jClass: Class<*>) : KClass<Any>, ClassB
         jClass.toString() + Reflection.REFLECTION_NOT_AVAILABLE
 
     companion object {
+        private val FUNCTION_CLASSES =
+            listOf(
+                Function0::class.java, Function1::class.java, Function2::class.java, Function3::class.java, Function4::class.java,
+                Function5::class.java, Function6::class.java, Function7::class.java, Function8::class.java, Function9::class.java,
+                Function10::class.java, Function11::class.java, Function12::class.java, Function13::class.java, Function14::class.java,
+                Function15::class.java, Function16::class.java, Function17::class.java, Function18::class.java, Function19::class.java,
+                Function20::class.java, Function21::class.java, Function22::class.java
+            ).mapIndexed { i, clazz -> clazz to i }.toMap()
+
         private val primitiveFqNames = HashMap<String, String>().apply {
             put("boolean", "kotlin.Boolean")
             put("char", "kotlin.Char")
@@ -137,8 +147,8 @@ public class ClassReference(override val jClass: Class<*>) : KClass<Any>, ClassB
             primitiveFqNames.values.associateTo(this) { kotlinName ->
                 "kotlin.jvm.internal.${kotlinName.substringAfterLast('.')}CompanionObject" to "$kotlinName.Companion"
             }
-            for (arity in 0 until 23) {
-                put("kotlin.jvm.functions.Function$arity", "kotlin.Function$arity")
+            for ((klass, arity) in FUNCTION_CLASSES) {
+                put(klass.name, "kotlin.Function$arity")
             }
         }
 
@@ -174,5 +184,13 @@ public class ClassReference(override val jClass: Class<*>) : KClass<Any>, ClassB
             }
             else -> classFqNames[jClass.name] ?: jClass.canonicalName
         }
+
+        public fun isInstance(value: Any?, jClass: Class<*>): Boolean {
+            FUNCTION_CLASSES[jClass]?.let { arity ->
+                return TypeIntrinsics.isFunctionOfArity(value, arity)
+            }
+            val objectType = if (jClass.isPrimitive) jClass.kotlin.javaObjectType else jClass
+            return objectType.isInstance(value)
+        }
     }
 }

libraries/stdlib/src/kotlin/reflect/KClasses.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+@file:kotlin.jvm.JvmName("KClasses")
+@file:Suppress("UNCHECKED_CAST")
+
+package kotlin.reflect
+
+/**
+ * Casts the given [value] to the class represented by this [KClass] object.
+ * Throws an exception if the value is `null` or if it is not an instance of this class.
+ *
+ * This is an experimental function that behaves as a similar function from kotlin.reflect.full on JVM.
+ *
+ * @see [KClass.isInstance]
+ * @see [KClass.safeCast]
+ */
+@SinceKotlin("1.3")
+@ExperimentalStdlibApi
+fun <T : Any> KClass<T>.cast(value: Any?): T {
+    if (!isInstance(value)) throw ClassCastException("Value cannot be cast to $qualifiedName")
+    return value as T
+}
+
+/**
+ * Casts the given [value] to the class represented by this [KClass] object.
+ * Returns `null` if the value is `null` or if it is not an instance of this class.
+ *
+ * This is an experimental function that behaves as a similar function from kotlin.reflect.full on JVM.
+ *
+ * @see [KClass.isInstance]
+ * @see [KClass.cast]
+ */
+@SinceKotlin("1.3")
+@ExperimentalStdlibApi
+fun <T : Any> KClass<T>.safeCast(value: Any?): T? {
+    return if (isInstance(value)) value as T else null
+}

libraries/tools/binary-compatibility-validator/reference-public-api/kotlin-stdlib-runtime-merged.txt

@@ -3299,6 +3299,7 @@ public final class kotlin/jvm/internal/ClassReference : kotlin/jvm/internal/Clas
 public final class kotlin/jvm/internal/ClassReference$Companion {
 	public final fun getClassQualifiedName (Ljava/lang/Class;)Ljava/lang/String;
 	public final fun getClassSimpleName (Ljava/lang/Class;)Ljava/lang/String;
+	public final fun isInstance (Ljava/lang/Object;Ljava/lang/Class;)Z
 }
 
 public final class kotlin/jvm/internal/CollectionToArray {
@@ -4382,6 +4383,11 @@ public abstract interface class kotlin/reflect/KClass : kotlin/reflect/KAnnotate
 	public abstract fun isSealed ()Z
 }
 
+public final class kotlin/reflect/KClasses {
+	public static final fun cast (Lkotlin/reflect/KClass;Ljava/lang/Object;)Ljava/lang/Object;
+	public static final fun safeCast (Lkotlin/reflect/KClass;Ljava/lang/Object;)Ljava/lang/Object;
+}
+
 public abstract interface class kotlin/reflect/KClassifier {
 }