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I need a tool to check if I break binary compatibility in my library. I stumbled across <https://github.com/Kotlin/binary-compatibility-validator|binary-compatibility-validator>, and it looks promising. However, it seems like it depends on Gradle, and I use Maven as my build system. Is it possible to use from Maven (possibly with <https://www.mojohaus.org/exec-maven-plugin/|Maven exec> if there is not proper Maven plugin)? Or is there some other similar tool which works from Maven?

unfortunately it looks to be quite tied to Gradle

there is a feature request <https://github.com/Kotlin/binary-compatibility-validator/issues/277>

in principle, everything in the <https://github.com/Kotlin/binary-compatibility-validator/tree/master/src/main/kotlin/api|kotlinx.api.validation> package appears to only depend on <https://asm.ow2.io/|ASM> and <https://github.com/JetBrains/kotlin/tree/master/libraries/kotlinx-metadata/jvm|kotlin-metadata-jvm>, so if you set up the classpath appropriately and re-implement the logic of <https://github.com/Kotlin/binary-compatibility-validator/blob/master/src/main/kotlin/KotlinApiBuildTask.kt|kotlinx.validation.AbiBuildWorker> outside of Gradle, you might be able to build your own CLI

Or not really a proper CLI, but a way to invoke it from Maven.

if you're only interested in validating JVM code, then it's quite simple to treat the existing BCV as a library and invoke it manually.

I wrote a custom Gradle plugin (because the existing BCV doesn't follow Gradle best practices), and it uses the existing BCV as a library.

Try taking a look at the code here:

<https://github.com/adamko-dev/kotlin-binary-compatibility-validator-mu/blob/94675fe0c65d7539923836002aa03c91ddcd7130/modules/bcv-gradle-plugin/src/main/kotlin/workers/BCVSignaturesWorker.kt#L68-L106>

Yes, I am using <https://central.sonatype.com/artifact/org.jetbrains.kotlinx/binary-compatibility-validator/0.16.3/overview|the library module> (which <https://github.com/Kotlin/binary-compatibility-validator/issues/278#issuecomment-2471054144|Jetbrains claim doesn't exist>, but I am using it anyway!), and it works if you add a few <https://github.com/Kotlin/binary-compatibility-validator/issues/278|missing dependencies>.

That's not a library module, that's the Gradle plugin. You can certainly use it, but it will include unnecessary code and dependencies (potentially the Gradle API?), but that probably won't be a problem for a Maven plugin

it has code that uses the Gradle API, but the dependency isn't there (as far as Maven is concerned), so as long as you don't touch classes that would fail to load in the absence of Gradle, it's :blob_no_problem:

Seems like if you only use the `kotlinx.validation.api` package, you don't get any Gradle dependencies. That package can be considered a library, it's just not released as such.

I created a simple Maven plugin: <https://gitlab.com/chromaway/core-tools/kotlin-bcv-maven-plugin>

It seems to me that this tool detects all changes to an API, not only _breaking_ changes, and you have to manually judge whether the changes are breaking. Right? Or did I some mistake in the Maven plugin?

Correct, it lists the complete API, so you would have to manually determine whether something is breaking or not (typically deleted/changed rows).

Added rows to interfaces (or abstract classes) is actually "in between": <https://wiki.openjdk.org/display/csr/Kinds+of+Compatibility#KindsofCompatibility-BinaryCompatibility>

there's a good guide for maintaining backwards compatibility for Kotlin libs, in case it helps

<https://kotlinlang.org/docs/api-guidelines-backward-compatibility.html>