++ reverts ^^

steps

1. Change the target sbt version with ^^: ^^1.0.0-RC2
2. Change the target Scala version with ++: ++2.12.2

problem

The target sbt version has been reverts:

> show pluginCrossBuild::sbtVersion
[info] 0.13.16-M1

> ^^1.0.0-RC2
[info] Setting `sbtVersion in pluginCrossBuild` to 1.0.0-RC2
[info] Set current project to t (in build file:/s/t-2017-07-17.1722/)

> show pluginCrossBuild::sbtVersion
[info] 1.0.0-RC2

> ++2.12.2
[info] Setting version to 2.12.2
[info] Reapplying settings...
[info] Set current project to t (in build file:/s/t-2017-07-17.1722/)

> show pluginCrossBuild::sbtVersion
[info] 0.13.16-M1

expectation

I expect my session-set target sbt version to not be affected by ++.

notes

sbt version: 0.13.16-M1

Workaround: Call ++ first, then ^^. 😞

[sjrd]

Don’t be so sure. You can have a multi-project build with an sbt plugin depending on other non-sbt-plugin projects. In such a case you still need to ++ for the other projects to have the right Scala version, don’t you?

It’s a pretty common setup too. A lot of sbt plugins try to abstract away their core logic from sbt integration, so that the core logic can be reused in other build tools or as CLI applications.

[dwijnand]

Situation’s pretty complicate now:

> show pluginCrossBuild::sbtVersion
[info] 0.13.16

> ^^1.0.0-RC3
[info] Setting `sbtVersion in pluginCrossBuild` to 1.0.0-RC3
[info] Set current project to sbt-whitesource (in build file:/d/sbt-whitesource/)

> show pluginCrossBuild::sbtVersion
[info] 1.0.0-RC3

> show scalaVersion
[info] 2.12.2

> ++2.12.3
[info] Setting version to 2.12.3
[info] Reapplying settings...
[info] Set current project to sbt-whitesource (in build file:/d/sbt-whitesource/)

> show pluginCrossBuild::sbtVersion
[info] 0.13.16

… I’m going back to using set.