Fixed #368:

 - added assertions to cause failure earlier
 - added test case
 - use BatchSourceFile length (characters) rather than file length (bytes)

2 files changed, 9 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/ScriptRunner.scala b/src/compiler/scala/tools/nsc/ScriptRunner.scala
index 78a63b2b23..d8ea282122 100644
--- a/src/compiler/scala/tools/nsc/ScriptRunner.scala
+++ b/src/compiler/scala/tools/nsc/ScriptRunner.scala
@@ -188,10 +188,12 @@ object ScriptRunner {
 
     val middle = {
       val f = new File(filename)
+      val bsf = getSourceFile(new PlainFile(f)).asInstanceOf[BatchSourceFile]
       new SourceFileFragment(
-          getSourceFile(new PlainFile(f)).asInstanceOf[BatchSourceFile],
+          bsf,
           headerLength(filename),
-          f.length.asInstanceOf[Int])
+          bsf.length)
+//          f.length.asInstanceOf[Int])
     }
     val end = new BatchSourceFile("<script trailer>", "\n} }\n".toCharArray)
 
diff --git a/src/compiler/scala/tools/nsc/util/SourceFile.scala b/src/compiler/scala/tools/nsc/util/SourceFile.scala
index e32cde800e..b4cf891a44 100644
--- a/src/compiler/scala/tools/nsc/util/SourceFile.scala
+++ b/src/compiler/scala/tools/nsc/util/SourceFile.scala
@@ -214,7 +214,11 @@ extends BatchSourceFile(name, contents) {
       underlyingFile,
       start,
       stop,
-      underlyingFile.content.slice(start, stop).toArray)
+      { assert(start >= 0)
+        assert(start <= stop)
+        assert(start <= underlyingFile.length)
+        assert(stop <= underlyingFile.length)
+        underlyingFile.content.slice(start, stop).toArray })
 
   def this(underlyingFile: BatchSourceFile, start: Int, stop: Int) =
     this(