Compilation fails when try to generate serialization staff for Map<String, Any>

[Fuud]

For example:

package kotlinx.serialization

import kotlin.test.Test
import kotlin.test.assertEquals

class JsTest {

    @Serializable
    data class DataWithMap(val a: Map<String, Any>)

    @Test
    fun jsTestWithMap() {
        val parsed = kotlinx.serialization.json.JSON.unquoted.parse<DataWithMap>("""{a: { "b" : "c" } }""")
        assertEquals(parsed, DataWithMap(mapOf("b" to "c")))
    }
}

will fail with:

:js:compileTestKotlin2Js
e: org.jetbrains.kotlin.js.facade.exceptions.TranslationRuntimeException: Unexpected error occurred compiling the following fragment: '/*
 * Copyright 2017 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package kotlinx.serialization

import kotlin.test.Test
import kotlin.test.assertEquals

class JsTest {

    @Serializable
    data class DataWithMap(val a: Map<String, Any>)

    @Test
    fun jsTestWithMap() {
        val parsed = kotlinx.serialization.json.JSON.unquoted.parse<DataWithMap>("""{a: { "b" : "c" } }""")
        assertEquals(parsed, DataWithMap(mapOf("b" to "c")))
    }
}' at (1,1) in G:/work/kotlinx.serialization/runtime/js/src/test/kotlin/kotlinx/serialization/JsTest.kt
        at org.jetbrains.kotlin.js.translate.general.Translation.translateFile(Translation.java:390)
        at org.jetbrains.kotlin.js.translate.general.Translation.doGenerateAst(Translation.java:299)
        at org.jetbrains.kotlin.js.translate.general.Translation.generateAst(Translation.java:261)
        at org.jetbrains.kotlin.js.facade.K2JSTranslator.translateUnits(K2JSTranslator.java:134)
        at org.jetbrains.kotlin.js.facade.K2JSTranslator.translate(K2JSTranslator.java:96)
        at org.jetbrains.kotlin.cli.js.K2JSCompiler.translate(K2JSCompiler.java:149)
        at org.jetbrains.kotlin.cli.js.K2JSCompiler.doExecute(K2JSCompiler.java:275)
        at org.jetbrains.kotlin.cli.js.K2JSCompiler.doExecute(K2JSCompiler.java:82)
        at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.java:109)
        at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.java:53)
        at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:92)
        at org.jetbrains.kotlin.daemon.CompileServiceImpl$compile$1$2.invoke(CompileServiceImpl.kt:387)
        at org.jetbrains.kotlin.daemon.CompileServiceImpl$compile$1$2.invoke(CompileServiceImpl.kt:97)
        at org.jetbrains.kotlin.daemon.CompileServiceImpl$doCompile$$inlined$ifAlive$lambda$2.invoke(CompileServiceImpl.kt:895)
        at org.jetbrains.kotlin.daemon.CompileServiceImpl$doCompile$$inlined$ifAlive$lambda$2.invoke(CompileServiceImpl.kt:97)
        at org.jetbrains.kotlin.daemon.common.DummyProfiler.withMeasure(PerfUtils.kt:137)
        at org.jetbrains.kotlin.daemon.CompileServiceImpl.checkedCompile(CompileServiceImpl.kt:925)
        at org.jetbrains.kotlin.daemon.CompileServiceImpl.doCompile(CompileServiceImpl.kt:894)
        at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:386)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:323)
        at sun.rmi.transport.Transport$1.run(Transport.java:200)
        at sun.rmi.transport.Transport$1.run(Transport.java:197)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
        at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:568)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:826)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$255(TCPTransport.java:683)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler$$Lambda$1/1341995085.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:682)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalArgumentException: Can't locate polymorphic serializer definition
        at org.jetbrains.kotlinx.serialization.compiler.backend.common.TypeUtilKt.findPolymorphicSerializer(TypeUtil.kt:118)
        at org.jetbrains.kotlinx.serialization.compiler.backend.common.TypeUtilKt.findTypeSerializer(TypeUtil.kt:72)
        at org.jetbrains.kotlinx.serialization.compiler.backend.js.SerializerJsTranslator.serializerInstance(SerializerJsTranslator.kt:187)
        at org.jetbrains.kotlinx.serialization.compiler.backend.js.SerializerJsTranslator.access$serializerInstance(SerializerJsTranslator.kt:46)
        at org.jetbrains.kotlinx.serialization.compiler.backend.js.SerializerJsTranslator$generateSave$1.invoke(SerializerJsTranslator.kt:145)
        at org.jetbrains.kotlinx.serialization.compiler.backend.js.SerializerJsTranslator$generateSave$1.invoke(SerializerJsTranslator.kt:46)
        at org.jetbrains.kotlinx.serialization.compiler.backend.js.JsCodegenUtilKt.buildFunction(JsCodegenUtil.kt:84)
        at org.jetbrains.kotlinx.serialization.compiler.backend.js.SerializerJsTranslator.generateFunction(SerializerJsTranslator.kt:51)
        at org.jetbrains.kotlinx.serialization.compiler.backend.js.SerializerJsTranslator.generateSave(SerializerJsTranslator.kt:119)
        at org.jetbrains.kotlinx.serialization.compiler.backend.common.SerializerCodegen.generateSaveIfNeeded(SerializerCodegen.kt:74)
        at org.jetbrains.kotlinx.serialization.compiler.backend.common.SerializerCodegen.generate(SerializerCodegen.kt:42)
        at org.jetbrains.kotlinx.serialization.compiler.backend.js.SerializerJsTranslator$Companion.translate(SerializerJsTranslator.kt:367)
        at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationJsExtension.generateClassSyntheticParts(SerializationJsExtension.kt:30)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator.generateClassSyntheticParts(ClassTranslator.kt:153)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator.translate(ClassTranslator.kt:111)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator.access$translate(ClassTranslator.kt:63)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator$Companion.translate(ClassTranslator.kt:564)
        at org.jetbrains.kotlin.js.translate.declaration.DeclarationBodyVisitor.generateClassOrObject(DeclarationBodyVisitor.kt:59)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator.translate(ClassTranslator.kt:108)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator.access$translate(ClassTranslator.kt:63)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator$Companion.translate(ClassTranslator.kt:568)
        at org.jetbrains.kotlin.js.translate.declaration.AbstractDeclarationVisitor.visitClassOrObject(AbstractDeclarationVisitor.kt:44)
        at org.jetbrains.kotlin.js.translate.declaration.DeclarationBodyVisitor.visitClassOrObject(DeclarationBodyVisitor.kt:47)
        at org.jetbrains.kotlin.js.translate.declaration.DeclarationBodyVisitor.visitClassOrObject(DeclarationBodyVisitor.kt:34)
        at org.jetbrains.kotlin.psi.KtVisitor.visitClass(KtVisitor.java:33)
        at org.jetbrains.kotlin.psi.KtClass.accept(KtClass.kt:34)
        at org.jetbrains.kotlin.js.translate.general.TranslatorVisitor.traverseContainer(TranslatorVisitor.java:43)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator.translate(ClassTranslator.kt:92)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator.access$translate(ClassTranslator.kt:63)
        at org.jetbrains.kotlin.js.translate.declaration.ClassTranslator$Companion.translate(ClassTranslator.kt:568)
        at org.jetbrains.kotlin.js.translate.declaration.AbstractDeclarationVisitor.visitClassOrObject(AbstractDeclarationVisitor.kt:44)
        at org.jetbrains.kotlin.js.translate.declaration.AbstractDeclarationVisitor.visitClassOrObject(AbstractDeclarationVisitor.kt:37)
        at org.jetbrains.kotlin.psi.KtVisitor.visitClass(KtVisitor.java:33)
        at org.jetbrains.kotlin.psi.KtClass.accept(KtClass.kt:34)
        at org.jetbrains.kotlin.js.translate.general.Translation.translateFile(Translation.java:382)
        ... 36 more

[sandwwraith]

Because there is no reflection on Kotlin/JS, it now seems impossible to use polymorphic serialization with type recording, and therefore Any is not serializable on JS. Perhaps this restriction will be relaxed in future design, and library will allow only to write such values.

[sandwwraith]

#101