Fix error messages on resolving cross-built modules and re-enable relevant neg tests

2 files changed, 11 insertions, 3 deletions

diff --git a/core/src/main/scala/mill/Main.scala b/core/src/main/scala/mill/Main.scala
index 873feed2..1dbae4c3 100644
--- a/core/src/main/scala/mill/Main.scala
+++ b/core/src/main/scala/mill/Main.scala
@@ -100,7 +100,15 @@ object Main {
             }
 
           case Mirror.Segment.Cross(cross) =>
-            resolve(tail, hierarchy.crossChildren.get._2, obj, rest, remainingCrossSelectors, newRevSelectorsSoFar)
+            val Some((crossGen, childMirror)) = hierarchy.crossChildren
+            val crossOptions = crossGen(hierarchy.node(obj, remainingCrossSelectors))
+            if (crossOptions.contains(cross)){
+              resolve(tail, childMirror, obj, rest, remainingCrossSelectors, newRevSelectorsSoFar)
+            }else{
+              Left("Cannot resolve cross " + renderSelector(newRevSelectorsSoFar.reverse))
+            }
+
+
         }
 
       case Nil => Left("Selector cannot be empty")
diff --git a/core/src/test/scala/mill/main/MainTests.scala b/core/src/test/scala/mill/main/MainTests.scala
index 75403e17..a4fd7011 100644
--- a/core/src/test/scala/mill/main/MainTests.scala
+++ b/core/src/test/scala/mill/main/MainTests.scala
@@ -44,8 +44,8 @@ object MainTests extends TestSuite{
         'pos1 - check(singleCross, "cross[210].suffix", Right(singleCross.cross("210").suffix))
         'pos2 - check(singleCross, "cross[211].suffix", Right(singleCross.cross("211").suffix))
         'neg1 - check(singleCross, "cross[210].doesntExist", Left("Cannot resolve task cross[210].doesntExist"))
-  //      'neg2 - check(outer, "cross[doesntExist].doesntExist", Left("Cannot resolve cross cross[doesntExist]"))
-  //      'neg2 - check(outer, "cross[doesntExist].target", Left("Cannot resolve cross cross[doesntExist]"))
+        'neg2 - check(singleCross, "cross[doesntExist].doesntExist", Left("Cannot resolve cross cross[doesntExist]"))
+        'neg2 - check(singleCross, "cross[doesntExist].suffix", Left("Cannot resolve cross cross[doesntExist]"))
       }
       'double - {