Allow to swap Scala mainline dependencies by Typelevel ones

cli/src/main/scala-2.11/coursier/cli/Helper.scala

@@ -6,6 +6,7 @@ import java.net.{ URL, URLClassLoader }
 import java.util.jar.{ Manifest => JManifest }
 import java.util.concurrent.Executors
 
+import coursier.cli.typelevel.Typelevel
 import coursier.ivy.IvyRepository
 import coursier.util.{Print, Parse}
 
@@ -287,7 +288,8 @@ class Helper(
     filter = Some(dep => keepOptional || !dep.optional),
     userActivations =
       if (userEnabledProfiles.isEmpty) None
-      else Some(userEnabledProfiles.iterator.map(_ -> true).toMap)
+      else Some(userEnabledProfiles.iterator.map(_ -> true).toMap),
+    mapDependencies = if (typelevel) Some(Typelevel.swap(_)) else None
   )
 
   val loggerFallbackMode =

cli/src/main/scala-2.11/coursier/cli/Options.scala

@@ -85,6 +85,8 @@ case class CommonOptions(
   @Value("profile")
   @Short("F")
     profile: List[String],
+  @Help("Swap the mainline Scala JARs by Typelevel ones")
+    typelevel: Boolean = false,
   @Recurse
     cacheOptions: CacheOptions
 ) {

cli/src/main/scala-2.11/coursier/cli/typelevel/Typelevel.scala

@@ -0,0 +1,32 @@
+package coursier.cli.typelevel
+
+import coursier.{Dependency, Module}
+
+object Typelevel {
+
+  val mainLineOrg = "org.scala-lang"
+  val typelevelOrg = "org.typelevel"
+
+  val modules = Set(
+    "scala-compiler",
+    "scala-library",
+    "scala-library-all",
+    "scala-reflect",
+    "scalap"
+    // any other?
+  )
+
+  def swap(module: Module): Module =
+    if (module.organization == mainLineOrg && modules(module.name) && module.attributes.isEmpty)
+      module.copy(
+        organization = typelevelOrg
+      )
+    else
+      module
+
+  def swap(dependency: Dependency): Dependency =
+    dependency.copy(
+      module = swap(dependency.module)
+    )
+
+}

core/shared/src/main/scala/coursier/core/Resolution.scala

@@ -538,7 +538,8 @@ final case class Resolution(
   filter: Option[Dependency => Boolean],
   osInfo: Activation.Os,
   jdkVersion: Option[Version],
-  userActivations: Option[Map[String, Boolean]]
+  userActivations: Option[Map[String, Boolean]],
+  mapDependencies: Option[Dependency => Dependency]
 ) {
 
   def copyWithCache(
@@ -552,6 +553,7 @@ final case class Resolution(
     osInfo: Activation.Os = osInfo,
     jdkVersion: Option[Version] = jdkVersion,
     userActivations: Option[Map[String, Boolean]] = userActivations
+    // don't allow changing mapDependencies here - that would invalidate finalDependenciesCache
   ): Resolution =
     copy(
       rootDependencies,
@@ -578,7 +580,8 @@ final case class Resolution(
       if (deps == null)
         projectCache.get(dep.moduleVersion) match {
           case Some((_, proj)) =>
-            val res = finalDependencies(dep, proj).filter(filter getOrElse defaultFilter)
+            val res0 = finalDependencies(dep, proj).filter(filter getOrElse defaultFilter)
+            val res = mapDependencies.fold(res0)(res0.map(_))
             finalDependenciesCache0.put(dep, res)
             res
           case None => Nil

core/shared/src/main/scala/coursier/package.scala

@@ -75,7 +75,8 @@ package object coursier {
       filter: Option[Dependency => Boolean] = None,
       osInfo: Activation.Os = Activation.Os.fromProperties(sys.props.toMap),
       jdkVersion: Option[Version] = sys.props.get("java.version").flatMap(Parse.version),
-      userActivations: Option[Map[String, Boolean]] = None
+      userActivations: Option[Map[String, Boolean]] = None,
+      mapDependencies: Option[Dependency => Dependency] = None
     ): Resolution =
       core.Resolution(
         rootDependencies,
@@ -88,7 +89,8 @@ package object coursier {
         filter,
         osInfo,
         jdkVersion,
-        userActivations
+        userActivations,
+        mapDependencies
       )
   }