I use the following project structure sbtin Intelli-j 13.1
.
├── build.sbt
├── project
│ ├── Build.scala
│ ├── plugins.sbt
├── src
│ ├── main
│ └── test
└── target
Mine is built.sbtvery simple, I just declare some dependencies.
Mine is a project/Build.scalalittle more complicated, it defines a new project using:
lazy val RiepeteKernel = Project (id = "riepete-kernel", base = file ("."), settings = defaultSettings)
Intellij doesn't seem to like it. He installs two additional modules in the project settings, for example:

And when I try to compile my project, I get the following error:
Error:scalac: Output path /home/simao/code/riepete/project/target/idea-test-classes is shared between:
Module 'riepete-build' tests, Module 'riepete-kernel-build' tests Output path /home/simao/code/riepete/project/target/idea-classes
is shared between: Module 'riepete-build' production,
Module 'riepete-kernel-build' production Please configure separate output
paths to proceed with the compilation.
TIP: you can use Project Artifacts to combine compiled classes if needed.
sbt dist , , intellij , , , intellij.
intellij ?