title: Building a cross-build sbt project in Intellij
body: <p>I have a sbt project with three modules A, B, Common wherein </p>
  
  <ul>
  <li>A is compatible with scala version of 2.11.12 and depends on Common</li>
  <li>B is compatible with scala version of 2.12.7 and depends on Common</li>
  <li>Common can cross compile with both 2.11.12, 2.12.7 versions</li>
  </ul>
  
  <p>To support this I have created a <code>build.sbt</code> as following:</p>
  
  <pre><code>import sbt._
  
  val scalaL = "2.11.12"
  val scalaH = "2.12.7"
  
  lazy val common = (project in file("common"))
    .settings(crossScalaVersions := Seq(scalaH, scalaL))
  
  lazy val A = (project in file("A"))
    .settings(scalaVersion := scalaL)
    .dependsOn(common)
  
  lazy val B = (project in file("B"))
    .settings(scalaVersion := scalaH)
    .dependsOn(common)
  
  lazy val root = (project in file("."))
    .aggregate(common, B, A)
    .settings(crossScalaVersions := List())
  </code></pre>
  
  <p>I was able to <code>update</code>, <code>compile</code> this project from sbt shell by supplying the <code>+</code> prefix. </p>
  
  <p>But when I tried building the project in Idea Intellij Ultimate 2017.3 version using the sbt project refresh option, it broke with following error:</p>
  
  <pre><code>Error while importing sbt project:
  
  ;reload; set _root_.org.jetbrains.sbt.StructureKeys.sbtStructureOptions in Global := "download resolveClassifiers" ;*/*:dumpStructureTo /tmp/sbt-structure1.xml; session clear-all
  [info] Loading settings for project global-plugins from idea.sbt ...
  [info] Loading global plugins from /home/bala/.sbt/1.0/plugins
  [info] Loading project definition from /home/bala/ether-streaming/cross2/project
  [info] Loading settings for project root from build.sbt ...
  [warn] Discarding 1 session setting.  Use 'session save' to persist session settings.
  [info] Set current project to root (in build file:/home/bala/ether-streaming/cross2/)
  [info] Defining Global / sbtStructureOptions
  [info] The new value will be used by Global / ssOptions
  [info] Reapplying settings...
  [info] Set current project to root (in build file:/home/bala/ether-streaming/cross2/)
  [info] Updating A...
  [warn]  module not found: common#common_2.11;0.1.0-SNAPSHOT
  [warn] ==== local: tried
  [warn]   /home/bala/.ivy2/local/common/common_2.11/0.1.0-SNAPSHOT/ivys/ivy.xml
  [warn] ==== public: tried
  [warn]   https://repo1.maven.org/maven2/common/common_2.11/0.1.0-SNAPSHOT/common_2.11-0.1.0-SNAPSHOT.pom
  [warn] ==== local-preloaded-ivy: tried
  [warn]   /home/bala/.sbt/preloaded/common/common_2.11/0.1.0-SNAPSHOT/ivys/ivy.xml
  [warn] ==== local-preloaded: tried
  [warn]   file:////home/bala/.sbt/preloaded/common/common_2.11/0.1.0-SNAPSHOT/common_2.11-0.1.0-SNAPSHOT.pom
  [warn]  ::::::::::::::::::::::::::::::::::::::::::::::
  [warn]  ::          UNRESOLVED DEPENDENCIES         ::
  [warn]  ::::::::::::::::::::::::::::::::::::::::::::::
  [warn]  :: common#common_2.11;0.1.0-SNAPSHOT: not found
  [warn]  ::::::::::::::::::::::::::::::::::::::::::::::
  [warn]
  [warn]  Note: Unresolved dependencies path:
  [warn]      common:common_2.11:0.1.0-SNAPSHOT
  [warn]        +- a:a_2.11:0.1.0-SNAPSHOT
  [error] sbt.librarymanagement.ResolveException: unresolved dependency: common#common_2.11;0.1.0-SNAPSHOT: not found
  [error]     at sbt.internal.librarymanagement.IvyActions$.resolveAndRetrieve(IvyActions.scala:332)
  [error]     at sbt.internal.librarymanagement.IvyActions$.$anonfun$updateEither$1(IvyActions.scala:208)
  [error]     at sbt.internal.librarymanagement.IvySbt$Module.$anonfun$withModule$1(Ivy.scala:239)
  [error]     at sbt.internal.librarymanagement.IvySbt.$anonfun$withIvy$1(Ivy.scala:204)
  [error]     at sbt.internal.librarymanagement.IvySbt.sbt$internal$librarymanagement$IvySbt$$action$1(Ivy.scala:70)
  [error]     at sbt.internal.librarymanagement.IvySbt$$anon$3.call(Ivy.scala:77)
  [error]     at xsbt.boot.Locks$GlobalLock.withChannel$1(Locks.scala:93)
  [error]     at xsbt.boot.Locks$GlobalLock.xsbt$boot$Locks$GlobalLock$$withChannelRetries$1(Locks.scala:78)
  [error]     at xsbt.boot.Locks$GlobalLock$$anonfun$withFileLock$1.apply(Locks.scala:97)
  [error]     at xsbt.boot.Using$.withResource(Using.scala:10)
  [error]     at xsbt.boot.Using$.apply(Using.scala:9)
  [error]     at xsbt.boot.Locks$GlobalLock.ignoringDeadlockAvoided(Locks.scala:58)
  [error]     at xsbt.boot.Locks$GlobalLock.withLock(Locks.scala:48)
  [error]     at xsbt.boot.Locks$.apply0(Locks.scala:31)
  [error]     at xsbt.boot.Locks$.apply(Locks.scala:28)
  [error]     at sbt.internal.librarymanagement.IvySbt.withDefaultLogger(Ivy.scala:77)
  [error]     at sbt.internal.librarymanagement.IvySbt.withIvy(Ivy.scala:199)
  [error]     at sbt.internal.librarymanagement.IvySbt.withIvy(Ivy.scala:196)
  [error]     at sbt.internal.librarymanagement.IvySbt$Module.withModule(Ivy.scala:238)
  [error]     at sbt.internal.librarymanagement.IvyActions$.updateEither(IvyActions.scala:193)
  [error]     at sbt.librarymanagement.ivy.IvyDependencyResolution.update(IvyDependencyResolution.scala:20)
  [error]     at sbt.librarymanagement.DependencyResolution.update(DependencyResolution.scala:56)
  [error]     at sbt.internal.LibraryManagement$.resolve$1(LibraryManagement.scala:45)
  [error]     at sbt.internal.LibraryManagement$.$anonfun$cachedUpdate$12(LibraryManagement.scala:93)
  [error]     at sbt.util.Tracked$.$anonfun$lastOutput$1(Tracked.scala:68)
  [error]     at sbt.internal.LibraryManagement$.$anonfun$cachedUpdate$19(LibraryManagement.scala:106)
  [error]     at scala.util.control.Exception$Catch.apply(Exception.scala:224)
  [error]     at sbt.internal.LibraryManagement$.$anonfun$cachedUpdate$11(LibraryManagement.scala:106)
  [error]     at sbt.internal.LibraryManagement$.$anonfun$cachedUpdate$11$adapted(LibraryManagement.scala:89)
  [error]     at sbt.util.Tracked$.$anonfun$inputChanged$1(Tracked.scala:149)
  [error]     at sbt.internal.LibraryManagement$.cachedUpdate(LibraryManagement.scala:120)
  [error]     at sbt.Classpaths$.$anonfun$updateTask$5(Defaults.scala:2561)
  [error]     at scala.Function1.$anonfun$compose$1(Function1.scala:44)
  [error]     at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:40)
  [error]     at sbt.std.Transform$$anon$4.work(System.scala:67)
  [error]     at sbt.Execute.$anonfun$submit$2(Execute.scala:269)
  [error]     at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:16)
  [error]     at sbt.Execute.work(Execute.scala:278)
  [error]     at sbt.Execute.$anonfun$submit$1(Execute.scala:269)
  [error]     at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:178)
  [error]     at sbt.CompletionService$$anon$2.call(CompletionService.scala:37)
  [error]     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  [error]     at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
  [error]     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  [error]     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
  [error]     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
  [error]     at java.lang.Thread.run(Thread.java:748)
  [error] sbt.librarymanagement.ResolveException: unresolved dependency: common#common_2.11;0.1.0-SNAPSHOT: not found
  [error]     at sbt.internal.librarymanagement.IvyActions$.resolveAndRetrieve(IvyActions.scala:332)
  [error]     at sbt.internal.librarymanagement.IvyActions$.$anonfun$updateEither$1(IvyActions.scala:208)
  [error]     at sbt.internal.librarymanagement.IvySbt$Module.$anonfun$withModule$1(Ivy.scala:239)
  [error]     at sbt.internal.librarymanagement.IvySbt.$anonfun$withIvy$1(Ivy.scala:204)
  [error]     at sbt.internal.librarymanagement.IvySbt.sbt$internal$librarymanagement$IvySbt$$action$1(Ivy.scala:70)
  [error]     at sbt.internal.librarymanagement.IvySbt$$anon$3.call(Ivy.scala:77)
  [error]     at xsbt.boot.Locks$GlobalLock.withChannel$1(Locks.scala:93)
  [error]     at xsbt.boot.Locks$GlobalLock.xsbt$boot$Locks$GlobalLock$$withChannelRetries$1(Locks.scala:78)
  [error]     at xsbt.boot.Locks$GlobalLock$$anonfun$withFileLock$1.apply(Locks.scala:97)
  [error]     at xsbt.boot.Using$.withResource(Using.scala:10)
  [error]     at xsbt.boot.Using$.apply(Using.scala:9)
  [error]     at xsbt.boot.Locks$GlobalLock.ignoringDeadlockAvoided(Locks.scala:58)
  [error]     at xsbt.boot.Locks$GlobalLock.withLock(Locks.scala:48)
  [error]     at xsbt.boot.Locks$.apply0(Locks.scala:31)
  [error]     at xsbt.boot.Locks$.apply(Locks.scala:28)
  [error]     at sbt.internal.librarymanagement.IvySbt.withDefaultLogger(Ivy.scala:77)
  [error]     at sbt.internal.librarymanagement.IvySbt.withIvy(Ivy.scala:199)
  [error]     at sbt.internal.librarymanagement.IvySbt.withIvy(Ivy.scala:196)
  [error]     at sbt.internal.librarymanagement.IvySbt$Module.withModule(Ivy.scala:238)
  [error]     at sbt.internal.librarymanagement.IvyActions$.updateEither(IvyActions.scala:193)
  [error]     at sbt.librarymanagement.ivy.IvyDependencyResolution.update(IvyDependencyResolution.scala:20)
  [error]     at sbt.librarymanagement.DependencyResolution.update(DependencyResolution.scala:56)
  [error]     at sbt.internal.LibraryManagement$.resolve$1(LibraryManagement.scala:45)
  [error]     at sbt.internal.LibraryManagement$.$anonfun$cachedUpdate$12(LibraryManagement.scala:93)
  [error]     at sbt.util.Tracked$.$anonfun$lastOutput$1(Tracked.scala:68)
  [error]     at sbt.internal.LibraryManagement$.$anonfun$cachedUpdate$19(LibraryManagement.scala:106)
  [error]     at scala.util.control.Exception$Catch.apply(Exception.scala:224)
  [error]     at sbt.internal.LibraryManagement$.$anonfun$cachedUpdate$11(LibraryManagement.scala:106)
  [error]     at sbt.internal.LibraryManagement$.$anonfun$cachedUpdate$11$adapted(LibraryManagement.scala:89)
  [error]     at sbt.util.Tracked$.$anonfun$inputChanged$1(Tracked.scala:149)
  [error]     at sbt.internal.LibraryManagement$.cachedUpdate(LibraryManagement.scala:120)
  [error]     at sbt.Classpaths$.$anonfun$updateTask$5(Defaults.scala:2561)
  [error]     at scala.Function1.$anonfun$compose$1(Function1.scala:44)
  [error]     at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:40)
  [error]     at sbt.std.Transform$$anon$4.work(System.scala:67)
  [error]     at sbt.Execute.$anonfun$submit$2(Execute.scala:269)
  [error]     at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:16)
  [error]     at sbt.Execute.work(Execute.scala:278)
  [error]     at sbt.Execute.$anonfun$submit$1(Execute.scala:269)
  [error]     at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:178)
  [error]     at sbt.CompletionService$$anon$2.call(CompletionService.scala:37)
  [error]     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  [error]     at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
  [error]     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  [error]     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
  [error]     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
  [error]     at java.lang.Thread.run(Thread.java:748)
  [error] (A / update) sbt.librarymanagement.ResolveException: unresolved dependency: common#common_2.11;0.1.0-SNAPSHOT: not found
  [error] (A / ssExtractDependencies) sbt.librarymanagement.ResolveException: unresolved dependency: common#common_2.11;0.1.0-SNAPSHOT: not found
  [error] Total time: 1 s, completed 12 Dec, 2018 12:24:28 AM
  </code></pre>
  
  <p>From the error it is evident that it failed to resolve the 2.11 dependency of Common module while updating A. Similar error would have occurred if I would have ran <code>update</code> instead of <code>+ update</code> from shell.</p>
  
  <p>How can I make cross-building work in Intellij ? Or is there any existing option in Intellij to support cross-builds ?</p>