Better support for debugging

Author: odersky

compiler/src/dotty/tools/dotc/core/TypeErasure.scala

@@ -532,7 +532,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
     }
   } catch {
     case ex: AssertionError =>
-      println(s"no sig for $tp")
+      println(s"no sig for $tp because of ${ex.printStackTrace()}")
       throw ex
   }
 

compiler/src/dotty/tools/dotc/transform/Pickler.scala

@@ -11,6 +11,7 @@ import Periods._
 import Phases._
 import Symbols._
 import Flags.Module
+import reporting.ThrowingReporter
 import collection.mutable
 
 /** This phase pickles trees */
@@ -77,6 +78,7 @@ class Pickler extends Phase {
       testUnpickler(
           ctx.fresh
             .setPeriod(Period(ctx.runId + 1, FirstPhaseId))
+            .setReporter(new ThrowingReporter(ctx.reporter))
             .addMode(Mode.ReadPositions))
     result
   }