Mismatch between nullable and optional parameter #378

Author: Mr3zee

compiler-plugin/compiler-plugin-backend/src/main/kotlin/kotlinx/rpc/codegen/extension/RpcDeclarationScanner.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.declarations.IrProperty
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.util.dumpKotlinLike
+import org.jetbrains.kotlin.ir.util.hasDefaultValue
 
 /**
  * This class scans user declared RPC service
@@ -35,7 +36,7 @@ internal object RpcDeclarationScanner {
                         function = declaration,
                         arguments = ctx.versionSpecificApi.run {
                             declaration.valueParametersVS().memoryOptimizedMap { param ->
-                                ServiceDeclaration.Method.Argument(param, param.type)
+                                ServiceDeclaration.Method.Argument(param, param.type, param.hasDefaultValue())
                             }
                         },
                     )

compiler-plugin/compiler-plugin-backend/src/main/kotlin/kotlinx/rpc/codegen/extension/RpcStubGenerator.kt

@@ -815,6 +815,7 @@ internal class RpcStubGenerator(
                                 values {
                                     +stringConst(parameter.value.name.asString())
                                     +irRpcTypeCall(parameter.type)
+                                    +booleanConst(parameter.isOptional)
                                     +irListOfAnnotations(parameter.value)
                                 }
                             }

compiler-plugin/compiler-plugin-backend/src/main/kotlin/kotlinx/rpc/codegen/extension/ServiceDeclaration.kt

@@ -34,6 +34,7 @@ class ServiceDeclaration(
         class Argument(
             val value: IrValueParameter,
             val type: IrType,
+            val isOptional: Boolean,
         )
     }
 }

core/src/commonMain/kotlin/kotlinx/rpc/descriptor/RpcServiceDescriptor.kt

@@ -68,6 +68,7 @@ public sealed interface RpcInvokator<@Rpc T : Any> {
 public interface RpcParameter {
     public val name: String
     public val type: RpcType
+    public val isOptional: Boolean
 
     /**
      * List of annotations with target [AnnotationTarget.VALUE_PARAMETER].

core/src/commonMain/kotlin/kotlinx/rpc/descriptor/RpcServiceDescriptorDefault.kt

@@ -21,6 +21,7 @@ public class RpcCallableDefault<@Rpc T : Any>(
 public class RpcParameterDefault(
     override val name: String,
     override val type: RpcType,
+    override val isOptional: Boolean,
     override val annotations: List<Annotation>,
 ) : RpcParameter
 

krpc/krpc-core/src/commonMain/kotlin/kotlinx/rpc/krpc/internal/SerializationUtils.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package kotlinx.rpc.krpc.internal
@@ -15,6 +15,7 @@ import kotlinx.serialization.descriptors.buildClassSerialDescriptor
 import kotlinx.serialization.encoding.*
 import kotlinx.serialization.modules.SerializersModule
 import kotlin.reflect.KType
+import kotlin.reflect.KTypeParameter
 
 @OptIn(ExperimentalSerializationApi::class)
 internal fun SerializersModule.buildContextualInternal(type: KType): KSerializer<Any?>? {
@@ -113,7 +114,7 @@ public class CallableParametersSerializer(
                 elementName = param.name,
                 descriptor = callableSerializers[i].descriptor,
                 annotations = param.type.annotations,
-                isOptional = param.type.kType.isMarkedNullable,
+                isOptional = param.isOptional,
             )
         }
     }

krpc/krpc-test/src/commonMain/kotlin/kotlinx/rpc/krpc/test/KrpcTestService.kt

@@ -60,7 +60,8 @@ interface KrpcTestService {
     suspend fun doubleGenericParams(arg1: List<List<String>>)
     suspend fun mapParams(arg1: Map<String, Map<Int, List<String>>>)
     suspend fun customType(arg1: TestClass): TestClass
-    suspend fun nullable(arg1: String?): TestClass?
+    suspend fun nullableParam(arg1: String?): String
+    suspend fun nullableReturn(returnNull: Boolean): TestClass?
     suspend fun variance(arg2: TestList<in TestClass>, arg3: TestList2<TestClass>): TestList<out TestClass>?
 
     suspend fun nonSerializableClass(localDate: LocalDate): LocalDate

krpc/krpc-test/src/commonMain/kotlin/kotlinx/rpc/krpc/test/KrpcTestServiceBackend.kt

@@ -97,8 +97,12 @@ class KrpcTestServiceBackend : KrpcTestService {
         return arg1
     }
 
-    override suspend fun nullable(arg1: String?): TestClass? {
-        return if (arg1 == null) null else TestClass()
+    override suspend fun nullableParam(arg1: String?): String {
+        return arg1 ?: "null"
+    }
+
+    override suspend fun nullableReturn(returnNull: Boolean): TestClass? {
+        return if (returnNull) null else TestClass()
     }
 
     override suspend fun variance(

krpc/krpc-test/src/commonMain/kotlin/kotlinx/rpc/krpc/test/KrpcTransportTestBase.kt

@@ -226,12 +226,21 @@ abstract class KrpcTransportTestBase {
     }
 
     @Test
-    open fun nullable() = runTest {
-        val result = client.nullable("test")
-        assertEquals(TestClass(), result)
+    open fun nullableParameter() = runTest {
+        val result = client.nullableParam("test")
+        assertEquals("test", result)
+
+        val result2 = client.nullableParam(null)
+        assertEquals("null", result2)
+    }
+
+    @Test
+    open fun nullableReturn() = runTest {
+        val result = client.nullableReturn(returnNull = true)
+        assertEquals(null, result)
 
-        val result2 = client.nullable(null)
-        assertEquals(null, result2)
+        val result2 = client.nullableReturn(returnNull = false)
+        assertEquals(TestClass(), result2)
     }
 
     @Test
@@ -345,7 +354,7 @@ abstract class KrpcTransportTestBase {
     @Test
     open fun testNullables() = runTest {
         assertEquals(1, client.nullableInt(1))
-        assertNull(client.nullable(null))
+        assertNull(client.nullableReturn(returnNull = true))
     }
 
     @Test

krpc/krpc-test/src/commonTest/kotlin/kotlinx/rpc/krpc/test/LocalTransportTest.kt

@@ -52,7 +52,7 @@ class ProtoBufLocalTransportTest : LocalTransportTest() {
 
     // 'null' is not supported in ProtoBuf
     @Test
-    override fun nullable(): TestResult = runTest { }
+    override fun nullableReturn(): TestResult = runTest { }
 
     @Test
     override fun testByteArraySerialization(): TestResult = runTest { }