java.lang.NoSuchMethodError when parsing a JSON stream on Java 8

[madhead]

Describe the bug

I suspect the JSON format to be prone to this issue: plasma-umass/doppio#497 (comment)

The problem seems to be in the CharsetReader's constructor, on the line ＃23:

kotlinx.serialization/formats/json/jvmMain/src/kotlinx/serialization/json/internal/CharsetReader.kt

Lines 18 to 24 in 6dbb8a9

	init {
	decoder = charset.newDecoder()
	.onMalformedInput(CodingErrorAction.REPLACE)
	.onUnmappableCharacter(CodingErrorAction.REPLACE)
	byteBuffer = ByteBuffer.wrap(ByteArrayPool8k.take())
	byteBuffer.flip() // Make empty
	}

It seem that this class is compiled with a higher language level and, running on Java 8, causing the issue.

I've javap-ed the CharsetReader class (from the 1.5.0 versio of the library) and although I see the its class version is 52 (Java 8) it seems to be not enough for this nasty bug. The bytecode seems to use the ByteBuffer, which is incorrect 👇

It seems that a proper compiler option needs to be passed during the compilation process. The other way to solve this is using a manual cast.

To Reproduce

Please, refer to this minimal reproducible example: https://github.com/madhead/kotlinx-serialization-json-java8. Follow its README.

Basically, to reproduce the issues one needs to call Json.decodeFromStream on Java 8. As a result, he gets an exception like this:

Exception in thread "main" java.lang.NoSuchMethodError: java.nio.ByteBuffer.flip()Ljava/nio/ByteBuffer;
        at kotlinx.serialization.json.internal.CharsetReader.<init>(CharsetReader.kt:23)
        at kotlinx.serialization.json.internal.JavaStreamSerialReader.<init>(JvmJsonStreams.kt:258)
        at kotlinx.serialization.json.JvmStreamsKt.decodeFromStream(JvmStreams.kt:59)
        at me.madhead.kotlinx.serialization.json.java8.AppKt.main(App.kt:13)
        at me.madhead.kotlinx.serialization.json.java8.AppKt.main(App.kt)

Expected behavior

No exception is thrown, the stream is parsed correctly.

Environment

• Kotlin platforms: JVM
• JVM: 8.x

  openjdk version "1.8.0_322"
  OpenJDK Runtime Environment (Temurin)(build 1.8.0_322-b06)
  OpenJDK 64-Bit Server VM (Temurin)(build 25.322-b06, mixed mode)
  

• Kotlin version: 1.8.10
• Library version: 1.5.0

[madhead]

Actually, --release is a javac option, a shortcut over --source + --target + --bootclasspath (JEP ＃247, and an article for mortals, where they explain the need for this option… with Buffer's flip() method!)

There seems to be no such option as bootclasspath for the kotlinc, right?

So, I guess, casting manually is the easiest fix for this particular bug. There are only two flips in the whole codebase…

[lukellmann]

There seems to be no such option as bootclasspath for the kotlinc, right?

but there is an option like release: https://kotlinlang.org/docs/compiler-reference.html#xjdk-release-version

[madhead]

@lukellmann, indeed. But here we need specifically the bootclasspath, I guess. It's not only about targeting a specific JVM version, but using it's rt.jar during the compilation process:

javac … -Xbootclasspath ${jdk8path}/jre/lib/rt.jar

Also, the default value for the release is already 1.8 and it didn't work apparently.

Anyway, I'm just afraid of introducing such a change to the build process (and I obviously don't have enough knowledge to do that). I guess it may require some access to the TeamCity configs or what. So let the team think of it.