- Add `mill version` command

- Make `Evaluator` robust against `null` results

3 files changed, 48 insertions, 1 deletions

diff --git a/main/src/mill/main/MainModule.scala b/main/src/mill/main/MainModule.scala
index 7c84f74a..32281407 100644
--- a/main/src/mill/main/MainModule.scala
+++ b/main/src/mill/main/MainModule.scala
@@ -30,7 +30,11 @@ trait MainModule extends mill.Module{
   implicit def millDiscover: mill.define.Discover[_]
   implicit def millScoptTasksReads[T] = new mill.main.Tasks.Scopt[T]()
   implicit def millScoptEvaluatorReads[T] = new mill.main.EvaluatorScopt[T]()
-
+  def version() = mill.T.command {
+    val res = System.getProperty("MILL_VERSION")
+    println(res)
+    res
+  }
   /**
     * Resolves a mill query string and prints out the tasks it resolves to.
     */
diff --git a/main/test/src/mill/eval/EvaluationTests.scala b/main/test/src/mill/eval/EvaluationTests.scala
index 66147963..9c215086 100644
--- a/main/test/src/mill/eval/EvaluationTests.scala
+++ b/main/test/src/mill/eval/EvaluationTests.scala
@@ -247,6 +247,32 @@ object EvaluationTests extends TestSuite{
           !overriden.contains("object1")
         )
       }
+      'nullTasks - {
+        import nullTasks._
+        val checker = new Checker(nullTasks)
+        checker(nullTarget1, null, Agg(nullTarget1), extraEvaled = -1)
+        checker(nullTarget1, null, Agg(), extraEvaled = -1)
+        checker(nullTarget2, null, Agg(nullTarget2), extraEvaled = -1)
+        checker(nullTarget2, null, Agg(), extraEvaled = -1)
+        checker(nullTarget3, null, Agg(nullTarget3), extraEvaled = -1)
+        checker(nullTarget3, null, Agg(), extraEvaled = -1)
+        checker(nullTarget4, null, Agg(nullTarget4), extraEvaled = -1)
+        checker(nullTarget4, null, Agg(), extraEvaled = -1)
+
+        val nc1 = nullCommand1()
+        val nc2 = nullCommand2()
+        val nc3 = nullCommand3()
+        val nc4 = nullCommand4()
+
+        checker(nc1, null, Agg(nc1), extraEvaled = -1, secondRunNoOp = false)
+        checker(nc1, null, Agg(nc1), extraEvaled = -1, secondRunNoOp = false)
+        checker(nc2, null, Agg(nc2), extraEvaled = -1, secondRunNoOp = false)
+        checker(nc2, null, Agg(nc2), extraEvaled = -1, secondRunNoOp = false)
+        checker(nc3, null, Agg(nc3), extraEvaled = -1, secondRunNoOp = false)
+        checker(nc3, null, Agg(nc3), extraEvaled = -1, secondRunNoOp = false)
+        checker(nc4, null, Agg(nc4), extraEvaled = -1, secondRunNoOp = false)
+        checker(nc4, null, Agg(nc4), extraEvaled = -1, secondRunNoOp = false)
+      }
 
       'tasksAreUncached - {
         // Make sure the tasks `left` and `middle` re-compute every time, while
diff --git a/main/test/src/mill/util/TestGraphs.scala b/main/test/src/mill/util/TestGraphs.scala
index 11f72d02..83e03576 100644
--- a/main/test/src/mill/util/TestGraphs.scala
+++ b/main/test/src/mill/util/TestGraphs.scala
@@ -196,6 +196,23 @@ object TestGraphs{
     override lazy val millDiscover: Discover[this.type] = Discover[this.type]
   }
 
+  object nullTasks extends  TestUtil.BaseModule{
+    val nullString: String = null
+    def nullTask1 = T.task{ nullString }
+    def nullTask2 = T.task{ nullTask1() }
+
+    def nullTarget1 = T{ nullString }
+    def nullTarget2 = T{ nullTarget1() }
+    def nullTarget3 = T{ nullTask1() }
+    def nullTarget4 = T{ nullTask2() }
+
+    def nullCommand1() = T.command{ nullString }
+    def nullCommand2() = T.command{ nullTarget1() }
+    def nullCommand3() = T.command{ nullTask1() }
+    def nullCommand4() = T.command{ nullTask2() }
+
+    override lazy val millDiscover: Discover[this.type] = Discover[this.type]
+  }
 
   object singleCross extends TestUtil.BaseModule {
     object cross extends mill.Cross[Cross]("210", "211", "212")