animal sniffer does not catch ByteBuffer's usages that break in Java 8 when compiled with Java 9+

[voidzcy]

Originally reported in #7348. Existing usages are manually fixed by #7349. But we'd want to prevent this happens in the future.

Java 9 introduces overridden methods with covariant return types for the following methods in java.nio.ByteBuffer:

• position​(int newPosition)
• limit​(int newLimit)
• flip​()
• clear​()
• mark​()
• reset​()
• rewind​()

In Java 9 they all now return ByteBuffer, whereas the methods they override return Buffer, resulting in exceptions like this when executing on Java 8 and lower:

java.lang.NoSuchMethodError: java.nio.ByteBuffer.limit(I)Ljava/nio/ByteBuffer

This is because the generated byte code includes the static return type of the method, which is not found on Java 8 and lower because the overloaded methods with covariant return types don't exist (the issue appears even with source and target 8 or lower in compilation parameters). The solution is to cast ByteBuffer instances to Buffer before calling the method.

We'd expect animal sniffer to catch usages that could potentially break Java 8 users.

[ejona86]

#7348 references protocolbuffers/protobuf#7827 (comment) which references mojohaus/animal-sniffer#77 . I was just going to wait for a fix, checking each release, or noticing an update notification.

[ogolberg]

note that my PR (mojohaus/animal-sniffer#83) addressing this issue in animalsniffer has been open for a while - doesn't look like there's enough interest upstream to get it merged

at Toast, we're using a private fork of animalsniffer with the above fix applied

[cpovirk]

Yeah, based on your experience so far, I am likewise not too optimistic. I am hoping that maybe, if I post a beginning-to-end repro of the runtime failure, that will get some more traction on the PR. But we'll see.

[cpovirk]

(I should probably also mention why --release, their recommended alternative, isn't a great solution in our case.)

[ejona86]

@ogolberg, yeah, I had noticed it had been going on for a while. Although I had also seen the activity in July and figured in 1-2 more months I'd get more pessimistic, but I guess the useful discussion was with other users and not maintainers.

[cpovirk]

I gave it a shot in mojohaus/animal-sniffer#77 (comment)