NoSuchMethodError when the metabuild scalaVersion is 2.12.3

[dwijnand]

When upgrading the scalaVersion of sbt/io's metabuild to 2.12.3 (via upgrading to sbt 1.0.0-RC3) I get the following runtime error when running mimaReportBinaryIssues:

[error] java.lang.NoSuchMethodError: com.typesafe.tools.mima.core.Settings.StringSetting(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Lscala/tools/nsc/settings/MutableSettings$StringSetting;
[error] 	at com.typesafe.tools.mima.core.Settings.<init>(Settings.scala:14)
[error] 	at com.typesafe.tools.mima.core.Config$.setup(Config.scala:48)

NOTE this is only relevant for sbt 1 builds, where the Scala version is 2.12.x; not sbt 0.13 builds.

The cause is the changes to StringSetting in this commit scala/scala@be5126f (from scala/scala#5964), which is part of Scala 2.12.3, isn't backwards binary compatible with what sbt-mima-plugin 0.1.15 for sbt 1 was compiled against.

For the short term we can release a new version of sbt-mima-plugin compiled against Scala 2.12.3. But for the long term we should either:

• Rewrite the parts of MiMa that depend on scala.tools.nsc, or
• Consider fully cross-building MiMa.

[dwijnand]

Moved enhancements to #193. Short-term fix was merged in #190.

[dwijnand]

0.1.16 didn't fix this... 😑

[dwijnand]

The reason the release of 0.1.16 didn't fix this is due to an incremental compiler bug: it assumes that a minor version bump in scalaVersion (from 2.12.2 to 2.12.3) doesn't require recompiling files.

Most of the time this is true. But if you're a crazy scala.tools.nsc user... it's not.

I should've run clean before publishing.

For the short-term I've added that step explicitly to https://github.com/typesafehub/migration-manager/wiki/Releasing-MiMa. The long-term fix is (still) tracked in #190.

Going to release 0.1.17, actually with the exact same source..

[dwijnand]

Actually.. #194..