Aggregated tasks try Configurations from wrong projects when crossScalaVersions are mixed

[ches]

(Triage: can be labelled area/cross_building)

Another stateful cross-building issue, everyone's favorite kind by now? 😅

This is somewhat like #5497 except a Configuration is tried that should not be, rather than a cross version.

steps

Create a minimal build definition where projects differ in their crossScalaVersions and applied Configurations:

sbt.version = 1.4.6

val scala212 = "2.12.12"
val scala213 = "2.13.4"

inThisBuild(
  List(
    organization := "org.example",
    scalaVersion := scala213,
    crossScalaVersions := List(scala212, scala213),
  )
)

// https://github.com/sbt/sbt/issues/3698#issuecomment-473530474
crossScalaVersions := Nil

lazy val core = project

lazy val app = project
  .dependsOn(core)
  .configs(IntegrationTest)
  .settings(Defaults.itSettings)
  .settings(
    scalaVersion := scala212,
    crossScalaVersions := List(scala212),
  )

Or a variation where scalaVersion doesn't differ, to distinguish from that aspect of #5586:

lazy val core = project
  .settings(crossScalaVersions += "2.11.12")

lazy val app = project
  .dependsOn(core)
  .configs(IntegrationTest)
  .settings(Defaults.itSettings)

problem

When running a task aggregated on root with +, which works as expected when crossScalaVersions is homogeneous, sbt appears to construct a task invocation for a configuration scope that is defined on one project but not others:

sbt:demo> +it:compile
[info] Setting Scala version to 2.12.12 on 2 projects.
[info] Excluded 1 projects, run ++ 2.12.12 -v for more details.
[info] Reapplying settings...
[info] set current project to demo (in build file:/private/tmp/demo/)
[success] Total time: 0 s, completed Jan 21, 2021 12:10:56 AM
[error] Expected ';'
[error] No such setting/task
[error] ++  2.13.4 core/It/compile

expectation

The aggregated +it:compile runs the task for the project where the Configuration is added, not projects where it is not.

[eed3si9n]

Thanks for the report.

To supplement this, here's what happens without cross building as a reference.

ThisBuild / scalaVersion     := "2.13.4"
ThisBuild / version          := "0.1.0-SNAPSHOT"
ThisBuild / organization     := "com.example"

lazy val core = project

lazy val app = project
  .dependsOn(core)
  .configs(IntegrationTest)
  .settings(Defaults.itSettings)

sbt:hello> IntegrationTest/compile
[success] Total time: 0 s, completed Jan 23, 2021 2:32:59 PM
sbt:hello> core/IntegrationTest/compile
[error] No such setting/task
[error] core/IntegrationTest/compile
[error]

So the real aggregation feature of sbt is permissive of IntegrationTest not being present in core when called at the root level, but would error when specified as core/IntegrationTest/compile. So the emulated aggregation using + should follow that, and I agree with the expectation:

The aggregated +it:compile runs the task for the project where the Configuration is added, not projects where it is not.

[solarmosaic-kflorence]

Ran into this as well. Working around it for now with .configs(IntegrationTest).settings(IntegrationTest / test := {})