Fix `idea` project generation, and make `Result.Exception` display the offending stack trace so they're easier to debug

3 files changed, 8 insertions, 7 deletions

diff --git a/core/src/main/scala/mill/eval/Evaluator.scala b/core/src/main/scala/mill/eval/Evaluator.scala
index e9b34204..5aa3439c 100644
--- a/core/src/main/scala/mill/eval/Evaluator.scala
+++ b/core/src/main/scala/mill/eval/Evaluator.scala
@@ -214,9 +214,9 @@ class Evaluator[T](val workspacePath: Path,
                 target.evaluate(args)
               }
             }
-          }catch{
-            case NonFatal(e) =>
-              Result.Exception(e)
+          }catch{ case NonFatal(e) =>
+            val currentStack = new Exception().getStackTrace
+            Result.Exception(e, currentStack)
           }finally{
             System.setErr(err)
             System.setOut(out)
diff --git a/core/src/main/scala/mill/eval/Result.scala b/core/src/main/scala/mill/eval/Result.scala
index e0cc18bb..a9b2c70b 100644
--- a/core/src/main/scala/mill/eval/Result.scala
+++ b/core/src/main/scala/mill/eval/Result.scala
@@ -4,11 +4,11 @@ sealed trait Result[+T]
 object Result{
   implicit def create[T](t: => T): Result[T] = {
     try Success(t)
-    catch { case e: Throwable => Exception(e) }
+    catch { case e: Throwable => Exception(e, new java.lang.Exception().getStackTrace) }
   }
   case class Success[T](value: T) extends Result[T]
   case object Skipped extends Result[Nothing]
   sealed trait Failing extends Result[Nothing]
   case class Failure(msg: String) extends Failing
-  case class Exception(throwable: Throwable) extends Failing
+  case class Exception(throwable: Throwable, outerStack: Seq[StackTraceElement]) extends Failing
 }
\ No newline at end of file
diff --git a/core/src/main/scala/mill/main/RunScript.scala b/core/src/main/scala/mill/main/RunScript.scala
index 53347fd6..34a569fb 100644
--- a/core/src/main/scala/mill/main/RunScript.scala
+++ b/core/src/main/scala/mill/main/RunScript.scala
@@ -1,6 +1,6 @@
 package mill.main
 
-import java.io.PrintStream
+import java.io.{ByteArrayOutputStream, PrintStream}
 import java.nio.file.NoSuchFileException
 
 import ammonite.interp.Interpreter
@@ -127,7 +127,8 @@ object RunScript{
           case Right(t) => Mirror.renderSelector(t.segments.toList)
         }
         val fss = fs.map{
-          case Result.Exception(t) => t.toString
+          case Result.Exception(t, outerStack) =>
+            t.toString + t.getStackTrace.dropRight(outerStack.length).map("\n    " + _).mkString
           case Result.Failure(t) => t
         }
         s"$ks ${fss.mkString(", ")}"