[Reflection] Support java sealed classes in kotlin reflection

^KT-46778

compiler/testData/codegen/boxModernJdk/testsWithJava17/sealedJavaClassViaKotlinReflection.kt

@@ -0,0 +1,21 @@
+// WITH_REFLECT
+// FILE: Base.java
+public sealed class Base permits O, K {}
+
+// FILE: O.java
+public final class O extends Base {}
+
+// FILE: K.java
+public non-sealed class K extends Base {}
+
+// FILE: main.kt
+
+fun box(): String {
+    val klass = Base::class
+    if (!klass.isSealed) return "Error: Base is not sealed"
+    if (klass.isAbstract) return "Error: Base is not abstract"
+    return klass.sealedSubclasses
+        .joinToString("") { it.simpleName ?: "_No name provided_" }
+        .takeIf { it.isNotBlank() }
+        ?: "_No sealed subclasses found_"
+}

compiler/testData/codegen/boxModernJdk/testsWithJava17/sealedJavaInterfaceViaKotlinReflection.kt

@@ -0,0 +1,21 @@
+// WITH_REFLECT
+// FILE: Base.java
+public sealed interface Base permits O, K {}
+
+// FILE: O.java
+public non-sealed interface O extends Base {}
+
+// FILE: K.java
+public non-sealed interface K extends Base {}
+
+// FILE: main.kt
+
+fun box(): String {
+    val klass = Base::class
+    if (!klass.isSealed) return "Error: Base is not sealed"
+    if (klass.isAbstract) return "Error: Base is abstract"
+    return klass.sealedSubclasses
+        .joinToString("") { it.simpleName ?: "_No name provided_" }
+        .takeIf { it.isNotBlank() }
+        ?: "_No sealed subclasses found_"
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxModernJdkCodegenTestGenerated.java

@@ -146,6 +146,18 @@ public class BlackBoxModernJdkCodegenTestGenerated extends AbstractBlackBoxCodeg
         public void testSealedJavaClassViaJavaReflection() throws Exception {
             runTest("compiler/testData/codegen/boxModernJdk/testsWithJava17/sealedJavaClassViaJavaReflection.kt");
         }
+
+        @Test
+        @TestMetadata("sealedJavaClassViaKotlinReflection.kt")
+        public void testSealedJavaClassViaKotlinReflection() throws Exception {
+            runTest("compiler/testData/codegen/boxModernJdk/testsWithJava17/sealedJavaClassViaKotlinReflection.kt");
+        }
+
+        @Test
+        @TestMetadata("sealedJavaInterfaceViaKotlinReflection.kt")
+        public void testSealedJavaInterfaceViaKotlinReflection() throws Exception {
+            runTest("compiler/testData/codegen/boxModernJdk/testsWithJava17/sealedJavaInterfaceViaKotlinReflection.kt");
+        }
     }
 
     @Nested

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxModernJdkCodegenTestGenerated.java

@@ -146,6 +146,18 @@ public class IrBlackBoxModernJdkCodegenTestGenerated extends AbstractIrBlackBoxC
         public void testSealedJavaClassViaJavaReflection() throws Exception {
             runTest("compiler/testData/codegen/boxModernJdk/testsWithJava17/sealedJavaClassViaJavaReflection.kt");
         }
+
+        @Test
+        @TestMetadata("sealedJavaClassViaKotlinReflection.kt")
+        public void testSealedJavaClassViaKotlinReflection() throws Exception {
+            runTest("compiler/testData/codegen/boxModernJdk/testsWithJava17/sealedJavaClassViaKotlinReflection.kt");
+        }
+
+        @Test
+        @TestMetadata("sealedJavaInterfaceViaKotlinReflection.kt")
+        public void testSealedJavaInterfaceViaKotlinReflection() throws Exception {
+            runTest("compiler/testData/codegen/boxModernJdk/testsWithJava17/sealedJavaInterfaceViaKotlinReflection.kt");
+        }
     }
 
     @Nested

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

@@ -123,10 +123,12 @@ class ReflectJavaClass(
         get() = false
 
     override val isSealed: Boolean
-        get() = false
+        get() = Java16SealedRecordLoader.loadIsSealed(klass) ?: false
 
     override val permittedTypes: Collection<JavaClassifierType>
-        get() = emptyList()
+        get() = Java16SealedRecordLoader.loadGetPermittedSubclasses(klass)
+            ?.map(::ReflectJavaClassifierType)
+            ?: emptyList()
 
     override fun equals(other: Any?) = other is ReflectJavaClass && klass == other.klass
 
@@ -134,3 +136,47 @@ class ReflectJavaClass(
 
     override fun toString() = this::class.java.name + ": " + klass
 }
+
+private object Java16SealedRecordLoader {
+    class Cache(
+        val isSealed: Method?,
+        val getPermittedSubclasses: Method?,
+    )
+
+    private var _cache: Cache? = null
+
+    private fun buildCache(): Cache {
+        val clazz = Class::class.java
+
+        return try {
+            Cache(
+                clazz.getMethod("isSealed"),
+                clazz.getMethod("getPermittedSubclasses"),
+            )
+        } catch (e: NoSuchMethodException) {
+            Cache(null, null)
+        }
+    }
+
+    private fun initCache(): Cache {
+        var cache = this._cache
+        if (cache == null) {
+            cache = buildCache()
+            this._cache = cache
+        }
+        return cache
+    }
+
+    fun loadIsSealed(clazz: Class<*>): Boolean? {
+        val cache = initCache()
+        val isSealed = cache.isSealed ?: return null
+        return isSealed.invoke(clazz) as Boolean
+    }
+
+    fun loadGetPermittedSubclasses(clazz: Class<*>): Array<Class<*>>? {
+        val cache = initCache()
+        val getPermittedSubclasses = cache.getPermittedSubclasses ?: return null
+        @Suppress("UNCHECKED_CAST")
+        return getPermittedSubclasses.invoke(clazz) as Array<Class<*>>
+    }
+}