kotlinx.serialization: Enum class does not have .values() function when useIR = true

Describe the bug Project won’t compile when using custom serializer for enums and when using useIR = true.

e: java.lang.AssertionError: Enum class does not have .values() function
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.IrBuilderExtension$DefaultImpls.findEnumValuesMethod(GeneratorHelpers.kt:458)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator.findEnumValuesMethod(SerializerIrGenerator.kt:48)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.IrBuilderExtension$DefaultImpls.serializerInstance(GeneratorHelpers.kt:666)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator.serializerInstance(SerializerIrGenerator.kt:48)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.IrBuilderExtension$serializerInstance$2.invoke(GeneratorHelpers.kt:567)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.IrBuilderExtension$DefaultImpls.serializerInstance(GeneratorHelpers.kt:678)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator.serializerInstance(SerializerIrGenerator.kt:48)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.IrBuilderExtension$DefaultImpls.serializerInstance(GeneratorHelpers.kt:538)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator.serializerInstance(SerializerIrGenerator.kt:48)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator$generateSave$1.invoke(SerializerIrGenerator.kt:278)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator$generateSave$1.invoke(SerializerIrGenerator.kt:48)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.IrBuilderExtension$DefaultImpls.contributeFunction(GeneratorHelpers.kt:47)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator.contributeFunction(SerializerIrGenerator.kt:48)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator.generateSave(SerializerIrGenerator.kt:227)
	at org.jetbrains.kotlinx.serialization.compiler.backend.common.SerializerCodegen.generateSaveIfNeeded(SerializerCodegen.kt:105)
	at org.jetbrains.kotlinx.serialization.compiler.backend.common.SerializerCodegen.generate(SerializerCodegen.kt:34)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.SerializerIrGenerator$Companion.generate(SerializerIrGenerator.kt:503)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializerClassLowering.lower(SerializationLoweringExtension.kt:48)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitClass(SerializationLoweringExtension.kt:34)
	at org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid$DefaultImpls.visitClass(IrElementVisitorVoid.kt:44)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitClass(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitClass(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl.accept(IrClassImpl.kt:166)
	at org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl.acceptChildren(IrClassImpl.kt:171)
	at org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoidKt.acceptChildrenVoid(IrElementVisitorVoid.kt:275)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitClass(SerializationLoweringExtension.kt:35)
	at org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid$DefaultImpls.visitClass(IrElementVisitorVoid.kt:44)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitClass(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitClass(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl.accept(IrClassImpl.kt:166)
	at org.jetbrains.kotlin.ir.declarations.impl.IrFileImpl.acceptChildren(IrFileImpl.kt:59)
	at org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoidKt.acceptChildrenVoid(IrElementVisitorVoid.kt:275)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitElement(SerializationLoweringExtension.kt:30)
	at org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid$DefaultImpls.visitPackageFragment(IrElementVisitorVoid.kt:30)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitPackageFragment(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid$DefaultImpls.visitFile(IrElementVisitorVoid.kt:37)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitFile(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid$DefaultImpls.visitFile(IrElementVisitorVoid.kt:38)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitFile(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt$runOnFileInOrder$1.visitFile(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlin.ir.declarations.impl.IrFileImpl.accept(IrFileImpl.kt:56)
	at org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoidKt.acceptVoid(IrElementVisitorVoid.kt:271)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtensionKt.runOnFileInOrder(SerializationLoweringExtension.kt:28)
	at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationLoweringExtension.generate(SerializationLoweringExtension.kt:60)
	at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade$doGenerateFiles$1.invoke(JvmBackendFacade.kt:72)
	at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade$doGenerateFiles$1.invoke(JvmBackendFacade.kt:34)
	at org.jetbrains.kotlin.psi2ir.Psi2IrTranslator.generateModuleFragment(Psi2IrTranslator.kt:98)
	at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade.doGenerateFiles(JvmBackendFacade.kt:87)
	at org.jetbrains.kotlin.backend.jvm.JvmIrCodegenFactory.generateModule(JvmIrCodegenFactory.kt:40)
	at org.jetbrains.kotlin.codegen.KotlinCodegenFacade.compileCorrectFiles(KotlinCodegenFacade.java:35)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.generate(KotlinToJVMBytecodeCompiler.kt:616)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli(KotlinToJVMBytecodeCompiler.kt:203)
	at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:164)
	at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:51)
	at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:86)
	at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:44)
	at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:98)
	at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:346)
	at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:102)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileIncrementally(IncrementalCompilerRunner.kt:240)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.access$compileIncrementally(IncrementalCompilerRunner.kt:39)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner$compile$2.invoke(IncrementalCompilerRunner.kt:81)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compile(IncrementalCompilerRunner.kt:93)
	at org.jetbrains.kotlin.daemon.CompileServiceImplBase.execIncrementalCompiler(CompileServiceImpl.kt:601)
	at org.jetbrains.kotlin.daemon.CompileServiceImplBase.access$execIncrementalCompiler(CompileServiceImpl.kt:93)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:1633)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at java.rmi/sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:359)
	at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:200)
	at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:197)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.rmi/sun.rmi.transport.Transport.serviceCall(Transport.java:196)
	at java.rmi/sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:562)
	at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:796)
	at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:677)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:676)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:834)

To Reproduce Unable to reproduce with a clean project 😦

Expected behavior Should compile the same as with useIR = false

Environment

• Kotlin version: 1.4.0
• Library version: 1.0.0-RC
• Kotlin platforms: JVM
• Gradle version: 6.6
• IDE version (if bug is related to the IDE) IntellijIDEA 2020.2.1
• Other relevant context

openjdk version "11.0.7" 2020-04-14
OpenJDK Runtime Environment GraalVM CE 20.1.0 (build 11.0.7+10-jvmci-20.1-b02)
OpenJDK 64-Bit Server VM GraalVM CE 20.1.0 (build 11.0.7+10-jvmci-20.1-b02, mixed mode, sharing)