Scala 2.12.11 and 2.13.2

[ennru]

• Use the Scala versions used in Kafka core (to keep Embedded Kafka a little bit more Drop testkit support for Embedded Kafka #1114)
  • 2.12 https://mvnrepository.com/artifact/org.apache.kafka/kafka_2.12/2.6.0
  • 2.13 https://mvnrepository.com/artifact/org.apache.kafka/kafka_2.13/2.6.0
• Update the Silencer
• Adapt code to avoid new warnings in Scala 2.13.2

This makes Scala 2.13.2 the default version for all modules.

[ignasi35]

Sneaky!

[ennru]

Oh wow, Kafka hits Scala binary compatibility issues as it looks to me

[info]   java.lang.NoClassDefFoundError: scala/math/Ordering$$anon$7
[info]   at kafka.api.ApiVersion$.orderingByVersion(ApiVersion.scala:45)
[info]   at kafka.api.ApiVersion.compare(ApiVersion.scala:141)
[info]   at kafka.api.ApiVersion.compare$(ApiVersion.scala:140)
[info]   at kafka.api.KAFKA_2_6_IV0$.compare(ApiVersion.scala:348)
[info]   at kafka.api.KAFKA_2_6_IV0$.compare(ApiVersion.scala:348)
[info]   at scala.math.Ordered.$greater$eq(Ordered.scala:91)

https://travis-ci.org/github/akka/alpakka-kafka/jobs/733600592#L654

[ennru]

The error occurs in EmbeddedKafka on Scala 2.12.12 (Scala 2.13.3 works)
https://travis-ci.org/github/akka/alpakka-kafka/jobs/734533513#L443

[ennru]

The Kafka broker itself is compiled against Scala 2.12.11 (https://mvnrepository.com/artifact/org.apache.kafka/kafka_2.12/2.6.0).

[lrytz]

Seems there is a broken assumption here

Inline more aggressively when compiling the core jar since it's not meant to be used as a library [...] This is only safe if the Scala library version is the same at compile time and runtime

    if (project.name.equals('core'))
      inlineFrom = ["-opt-inline-from:scala.**", "-opt-inline-from:kafka.**", "-opt-inline-from:org.apache.kafka.**"]

https://github.com/apache/kafka/blob/2.6.0/build.gradle#L485-L492

[ennru]

Rolled back this PR to Scala 2.12.11 and 2.13.2 so we can continue dropping Embedded Kafka in #1209