Version conflicts and evictions when combining submodules

[Dennis4b]

Hi,

edit: this is quite a roundabout way to describe it, see second message

I am not sure if this is the intended behavior or not, but it has caused me some issues so I'd like to clarify.

Making a testcase takes some time so hopefully the following explanation suffices:

Suppose that in my main app definition (a plain ScalaModule) my ivyDeps depend on org.typelevel cats-core 1.1.0 and on cats-effect 0.10. The cats-effect dependency itself depends on cats-core 1.0.1, but this version gets evicted and we end up with cats-core 1.1.0 in our classpath, which I think is how it should be.

So something like:

object server extends ScalaModule {
      def ivyDeps = Agg (
          // cats-core 1.1.0
          // cats-effect 0.10
      )
     ....
}

Now suppose I separate my code into submodules. My main module has as ivyDeps cats-core 1.1.0, and in my submodule I only need cats-effect 0.10 - which then pulls in cats-core 1.0.1 for the submodule.

So something like:

object shared extends ScalaModule {
    def ivyDeps = Agg(
        // cats-effect 0.10, which depends on cats-core 1.0.1
    )
    ....
}
object server extends ScalaModule {
      def moduleDeps = Seq(shared)
      def ivyDeps = Agg (
          // cats-core 1.1.0
      )
     ....
}

In this case mill does not evict cats-core 1.0.1 and my server.runClasspath ends up with:

 "path": ".....maven2/org/typelevel/cats-core_2.12/1.0.1/cats-core_2.12-1.0.1.jar",
 "path": ".....maven2/org/typelevel/cats-core_2.12/1.1.0/cats-core_2.12-1.1.0.jar",

which causes all sorts of strange runtime problems.

Should eviction not take place here?

[Dennis4b]

A more straightforward example, only using cats-effect as an example, it's about the conflicting versions:

import mill._
import mill.scalalib._
import java.nio.file.Files

object server extends ScalaModule {
    def scalaVersion = "2.12.5"

    def ivyDeps = Agg (
        ivy"org.typelevel::cats-effect:0.9",
        ivy"org.typelevel::cats-effect:0.10"
    )
}

gives (correctly)

> mill show server.runClasspath | grep cats-effect
   "path": ".....maven2/org/typelevel/cats-effect_2.12/0.10/cats-effect_2.12-0.10.jar"

and

import mill._
import mill.scalalib._
import java.nio.file.Files

object shared extends ScalaModule {
    def ivyDeps = Agg (
        ivy"org.typelevel::cats-effect:0.9"
    )
}

object server extends ScalaModule {
    def moduleDeps = Seq(shared)

    def ivyDeps = Agg (
        ivy"org.typelevel::cats-effect:0.10"
    )
}

gives (unexpectedly, at least to me):

> mill show server.runClasspath | grep cats-effect
        "path": ".....maven2/org/typelevel/cats-effect_2.12/0.9/cats-effect_2.12-0.9.jar",
        "path": ".....maven2/org/typelevel/cats-effect_2.12/0.10/cats-effect_2.12-0.10.jar",

[francisdb]

I think this is a duplicate of #211 which was fixed recently (but not released yet)

[Dennis4b]

Ah yes it appears to be. Sorry, didn't see it among the (open) issues. Great that it's fixed!