Dependency with macros not working

[gmendonca]

Yo, I'm trying to make https://github.com/lloydmeta/enumeratum to work with bazel-deps:

  com.beachape:
    enumeratum:
      lang: scala
      version: "1.5.13"

And when trying to build, I'm getting:

error: macro implementation not found: findValues
(the most common reason for that is that you cannot use macro implementations in the same compilation run that defines them)

As per my understanding we're defaulting scala_import for any scala dependency, but there are situations where using https://github.com/bazelbuild/rules_scala/blob/master/docs/scala_macro_library.md or https://github.com/bazelbuild/rules_scala/blob/master/docs/scala_library.md would have a better fit. If my assumptions are correct, we could support this through an option kind:

  com.beachape:
    enumeratum:
      lang: scala
      kind: scala-macro
      version: "1.5.13"

[johnynek]

take a look at:

https://github.com/bazelbuild/rules_scala/issues/445 https://github.com/bazelbuild/rules_scala/issues/366

There are subtleties with some macro set ups and open issues not resolved.

To your point: yes, many external libraries could be non-macro imported, which would run ijar on them and could result in better cache hits, but I'm skeptical of that. ijar removes the code, which can only increase cache hit rates. But when you bump a version of a jar, it is very rare that the ijar would wind up being exactly the same after that. Furthermore, bumping external dependencies is pretty rare.

So, my bias would be to simplicity here.

That said, I'm open to adding optional options if we can make it clear what problem we are solving.

Thanks for taking the time to open an issue.

[gmendonca]

I'm closing this as I agree with you design choice. And, in the above case, importing like this does solves the issue:

  com.beachape:
    enumeratum-macros:
      lang: scala
      version: "1.5.10"
    enumeratum:
      exports:
        - "com.beachape:enumeratum-macros"
      lang: scala
      version: "1.5.13"