Targets living in cross modules can now be properly discovered, run and cached.

Try out the following commands on our Mill `build.sc` file to exercise this functionality

- `scalaplugin/target/mill run Core.cross[jarA].jar`
- `scalaplugin/target/mill run Core.cross[jarB].jar`
- `scalaplugin/target/mill run Core.cross[jarC].jar`

4 files changed, 62 insertions, 16 deletions

diff --git a/core/src/test/scala/mill/discover/ConsistencyTests.scala b/core/src/test/scala/mill/discover/ConsistencyTests.scala
index 67e22595..0591d5fc 100644
--- a/core/src/test/scala/mill/discover/ConsistencyTests.scala
+++ b/core/src/test/scala/mill/discover/ConsistencyTests.scala
@@ -1,6 +1,7 @@
 package mill.discover
 
 
+import mill.discover.Mirror.Segment.Label
 import mill.util.TestGraphs
 import utest._
 
@@ -15,7 +16,12 @@ object ConsistencyTests extends TestSuite{
       //
       // Maybe later we can convert them into compile errors somehow
 
-      val expected = List(List("down"), List("right"), List("left"), List("up"))
+      val expected = List(
+        List(Label("down")),
+        List(Label("right")),
+        List(Label("left")),
+        List(Label("up"))
+      )
 
       'diamond - {
         val inconsistent = Discovered.consistencyCheck(
diff --git a/core/src/test/scala/mill/discover/CrossModuleTests.scala b/core/src/test/scala/mill/discover/CrossModuleTests.scala
index c4e075da..8d8a86f6 100644
--- a/core/src/test/scala/mill/discover/CrossModuleTests.scala
+++ b/core/src/test/scala/mill/discover/CrossModuleTests.scala
@@ -2,6 +2,8 @@ package mill.discover
 
 import mill.{Module, T}
 import mill.define.Cross
+import mill.discover.Mirror.{LabelledTarget, Segment}
+import mill.discover.Mirror.Segment.Label
 import utest._
 
 object CrossModuleTests extends TestSuite{
@@ -17,7 +19,9 @@ object CrossModuleTests extends TestSuite{
           }
       }
 
-      val Some((gen, innerMirror)) = Discovered[outer.type]
+      val discovered = Discovered[outer.type]
+
+      val Some((gen, innerMirror)) = discovered
         .mirror
         .children
         .head._2
@@ -68,14 +72,49 @@ object CrossModuleTests extends TestSuite{
         assert(suffix == expected)
       }
     }
-    'crossCommands - {
-      object outer {
-        val cross = for (c <- mill.define.Cross("a", "b", "c")) yield new mill.Module {
-          def printIt() = T.command {
-            println("PRINTING IT: " + c)
-          }
-        }
+    'crossTargetDiscovery - {
+      object outer{
+        val crossed =
+          for(n <- Cross("2.10.6", "2.11.8", "2.12.4"))
+          yield new Module{ def scalaVersion = T{ n } }
       }
+      val discovered = Discovered[outer.type]
+
+      val segments = discovered.targets(outer).map(_.segments)
+      val expectedSegments = List(
+        List(Label("crossed"), Segment.Cross(List("2.10.6")), Label("scalaVersion")),
+        List(Label("crossed"), Segment.Cross(List("2.11.8")), Label("scalaVersion")),
+        List(Label("crossed"), Segment.Cross(List("2.12.4")), Label("scalaVersion"))
+      )
+      assert(segments == expectedSegments)
+      val targets = discovered.targets(outer).map(_.target)
+      val expected = List(
+        outer.crossed(List("2.10.6")).scalaVersion,
+        outer.crossed(List("2.11.8")).scalaVersion,
+        outer.crossed(List("2.12.4")).scalaVersion
+      )
+      assert(targets == expected)
+
+    }
+    'doubleCrossTargetDiscovery - {
+      object outer{
+        val crossed =
+          for{
+            n <- Cross("2.11.8", "2.12.4")
+            platform <- Cross("sjs0.6", "native0.3")
+          } yield new Module{ def suffix = T{ n + "_" + platform } }
+      }
+      val discovered = Discovered[outer.type]
+      val targets = discovered.targets(outer).map(_.target)
+      
+      val expected = List(
+        outer.crossed(List("sjs0.6", "2.11.8")).suffix,
+        outer.crossed(List("native0.3", "2.11.8")).suffix,
+        outer.crossed(List("sjs0.6", "2.12.4")).suffix,
+        outer.crossed(List("native0.3", "2.12.4")).suffix
+      )
+      assert(targets == expected)
+
     }
   }
 }
diff --git a/core/src/test/scala/mill/discover/DiscoveredTests.scala b/core/src/test/scala/mill/discover/DiscoveredTests.scala
index b09ff2de..7fa030eb 100644
--- a/core/src/test/scala/mill/discover/DiscoveredTests.scala
+++ b/core/src/test/scala/mill/discover/DiscoveredTests.scala
@@ -6,6 +6,7 @@ import mill.discover.Router.{ArgSig, EntryPoint}
 import utest._
 import mill.{Module, T}
 import mill.util.TestUtil.test
+import mill.discover.Mirror.Segment.Label
 object DiscoveredTests extends TestSuite{
 
   val tests = Tests{
@@ -44,12 +45,12 @@ object DiscoveredTests extends TestSuite{
       )
       assert(flattenedHierarchy == expectedHierarchy)
 
-      val mapped = discovered.targets(outer, Nil).map(x => x.segments -> x.target)
+      val mapped = discovered.targets(outer).map(x => x.segments -> x.target)
 
       val expected = Seq(
-        (List("classInstance", "single"), outer.classInstance.single),
-        (List("nested", "single"), outer.nested.single),
-        (List("single"), outer.single)
+        (List(Label("classInstance"), Label("single")), outer.classInstance.single),
+        (List(Label("nested"), Label("single")), outer.nested.single),
+        (List(Label("single")), outer.single)
       )
       assert(mapped.toSet == expected.toSet)
     }
diff --git a/core/src/test/scala/mill/discover/LabelingTests.scala b/core/src/test/scala/mill/discover/LabelingTests.scala
index a37c090c..94d91cda 100644
--- a/core/src/test/scala/mill/discover/LabelingTests.scala
+++ b/core/src/test/scala/mill/discover/LabelingTests.scala
@@ -3,7 +3,7 @@ package mill.discover
 import mill.define.Task
 import mill.util.TestGraphs
 import utest._
-
+import mill.discover.Mirror.Segment.Label
 object LabelingTests extends TestSuite{
 
   val tests = Tests{
@@ -15,10 +15,10 @@ object LabelingTests extends TestSuite{
       def check[T: Discovered](base: T, t: Task[_], relPath: Option[String]) = {
 
 
-        val names: Seq[(Task[_], Seq[String])] = Discovered.mapping(base).mapValues(_.segments).toSeq
+        val names: Seq[(Task[_], Seq[Mirror.Segment])] = Discovered.mapping(base).mapValues(_.segments).toSeq
         val nameMap = names.toMap
 
-        val targetLabel = nameMap.get(t).map(_.mkString("."))
+        val targetLabel = nameMap.get(t).map(_.map{case Label(v) => v}.mkString("."))
         assert(targetLabel == relPath)
       }
       'singleton - check(singleton, singleton.single, Some("single"))