Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Fix typos in jvm-api-guidelines-backward-compatibility.md #3

Open
wants to merge 1 commit into
base: main
Choose a base branch
from

Conversation

Legion2
Copy link

@Legion2 Legion2 commented Apr 10, 2023

While reading through I found these inconsistencies.

And recompile only the client: `kotlinc client.kt`. `ClientKt` doesn't work as expected anymore. It doesn't print `3`
And recompile only the library: `kotlinc library.kt`. `ClientKt` doesn't work as expected anymore. It doesn't print `3`
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I don't think it's a typo or a mistake. It demonstrates that if you change the return type of a function in your library, the clients will need to re-compile their code against the new version of your library code.

The client code was compiled to call the function that returns Number. However, because the return type was changed from Number to Int, such function doesn't exist anymore, so it fails with NoSuchMethodError. This pretty much happens because java is dynamically linked.

I'll leave it to @asm0dey, maybe we could add some details to this section so that it doesn't raise such questions

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yes, @IgnatBeresnev, it's correct. The backward compatibility issues mainly arise during split compilation, which we emulate in this example

Copy link
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think it depends on what do you compile the client.kt against, the source code (which was updated) or the binary (which is outdated). If compiled against the source code the error message should be java.lang.Integer instead of java.lang.Number, because the client was compiled against the version with the Int as return type. If compiled against the binary, there should no be any error, because the binary did not change and the client code was also not changed.

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@Legion2 The whole case was about split compilation, which is usually the case. Sometimes, it is in a more complex setup, but still.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

3 participants