improves traces and error messages

2 files changed, 19 insertions, 11 deletions

diff --git a/src/library/scala/reflect/ReflectionUtils.scala b/src/library/scala/reflect/ReflectionUtils.scala
index 6ea69cb80d..aa1285d5a0 100644
--- a/src/library/scala/reflect/ReflectionUtils.scala
+++ b/src/library/scala/reflect/ReflectionUtils.scala
@@ -33,20 +33,26 @@ object ReflectionUtils {
     System.getProperties.asScala.iterator
   }
 
-  private def searchForBootClasspath = (
+  private def inferBootClasspath: String = (
     systemProperties find (_._1 endsWith ".boot.class.path") map (_._2) getOrElse ""
   )
 
   def show(cl: ClassLoader) = {
-    def inferClasspath(cl: ClassLoader) = cl match {
-      case cl: java.net.URLClassLoader => "[" + (cl.getURLs mkString ",") + "]"
-      case _ => "<unknown>"
+    def inferClasspath(cl: ClassLoader): String = cl match {
+      case cl: java.net.URLClassLoader =>
+        "[" + (cl.getURLs mkString ",") + "]"
+      case cl if cl != null && cl.getClass.getName == "scala.tools.nsc.interpreter.AbstractFileClassLoader" =>
+        "[" + cl.asInstanceOf[{val root: api.RequiredFile}].root + "] and " + inferClasspath(cl.getParent)
+      case null =>
+        inferBootClasspath
+      case _ =>
+        "<unknown>"
     }
     cl match {
       case cl if cl != null =>
         "%s of type %s with classpath %s".format(cl, cl.getClass, inferClasspath(cl))
       case null =>
-        "primordial classloader with boot classpath [%s]".format(searchForBootClasspath)
+        "primordial classloader with boot classpath [%s]".format(inferClasspath(cl))
     }
   }
 
diff --git a/src/library/scala/reflect/makro/internal/Utils.scala b/src/library/scala/reflect/makro/internal/Utils.scala
index 3af58e1c88..3032d8e05d 100644
--- a/src/library/scala/reflect/makro/internal/Utils.scala
+++ b/src/library/scala/reflect/makro/internal/Utils.scala
@@ -102,7 +102,7 @@ package internal {
             else gen.mkMethodCall(staticModule("scala.reflect.package"), newTermName("manifestToConcreteTypeTag"), List(tpe), List(manifestInScope))
         }
       try c.typeCheck(result)
-      catch { case terr @ c.TypeError(pos, msg) => failTag(terr) }
+      catch { case terr @ c.TypeError(pos, msg) => failTag(result, terr) }
     }
 
     private def nonSyntheticManifestInScope(tpe: Type) = {
@@ -116,7 +116,7 @@ package internal {
     def materializeExpr(prefix: Tree, expr: Tree): Tree = {
       val result = translatingReificationErrors(c.reifyTree(prefix, expr))
       try c.typeCheck(result)
-      catch { case terr @ c.TypeError(pos, msg) => failExpr(terr) }
+      catch { case terr @ c.TypeError(pos, msg) => failExpr(result, terr) }
     }
 
     private def translatingReificationErrors(materializer: => Tree): Tree = {
@@ -130,17 +130,19 @@ package internal {
       }
     }
 
-    private def failTag(reason: Any): Nothing = {
+    private def failTag(result: Tree, reason: Any): Nothing = {
       val Apply(TypeApply(fun, List(tpeTree)), _) = c.macroApplication
       val tpe = tpeTree.tpe
       val PolyType(_, MethodType(_, tagTpe)) = fun.tpe
       val tagModule = tagTpe.typeSymbol.companionSymbol
       if (c.compilerSettings.contains("-Xlog-implicits"))
-        c.echo(c.enclosingPosition, "cannot materialize " + tagModule.name + "[" + tpe + "] because:\n" + reason)
+        c.echo(c.enclosingPosition, s"cannot materialize ${tagModule.name}[$tpe] as $result because:\n$reason")
       c.abort(c.enclosingPosition, "No %s available for %s".format(tagModule.name, tpe))
     }
 
-    private def failExpr(reason: Any): Nothing =
-      c.abort(c.enclosingPosition, "Cannot materialize Expr because:\n" + reason)
+    private def failExpr(result: Tree, reason: Any): Nothing = {
+      val Apply(_, expr :: Nil) = c.macroApplication
+      c.abort(c.enclosingPosition, s"Cannot materialize $expr as $result because:\n$reason")
+    }
   }
 }