Fixed #2099.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/UnPickler.scala b/src/compiler/scala/tools/nsc/symtab/classfile/UnPickler.scala
index 2b4d7d33de..e26e8d41ca 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/UnPickler.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/UnPickler.scala
@@ -201,7 +201,7 @@ abstract class UnPickler {
           // the "case Apply" in readTree() takes care of selecting the correct alternative
           //  after parsing the arguments.
           if (sym == NoSymbol && !owner.hasFlag(OVERLOADED)) {
-            errorBadSignature(
+            errorMissingRequirement(
               "reference " + (if (name.isTypeName) "type " else "value ") +
               name.decode + " of " + owner + " refers to nonexisting symbol.")
           }
@@ -813,6 +813,10 @@ abstract class UnPickler {
     private def errorBadSignature(msg: String) =
       throw new RuntimeException("malformed Scala signature of " + classRoot.name + " at " + readIndex + "; " + msg)
 
+    private def errorMissingRequirement(msg: String) =
+      if (settings.debug.value) errorBadSignature(msg)
+      else throw new IOException("class file needed by "+classRoot.name+" is missing.\n"+msg)
+
     private class LazyTypeRef(i: Int) extends LazyType {
       private val definedAtRunId = currentRunId
       private val p = phase