1.1 --- a/src/Pure/System/build.scala	Wed Jul 18 17:22:59 2012 +0200
     1.2 +++ b/src/Pure/System/build.scala	Wed Jul 18 17:27:28 2012 +0200
     1.3 @@ -166,6 +166,11 @@
     1.4          val full_name =
     1.5            if (entry.reset) entry.name
     1.6            else parent.name + "-" + entry.name
     1.7 +
     1.8 +        if (entry.name == "") error("Bad session name")
     1.9 +        if (infos.exists(_.name == full_name))
    1.10 +          error("Duplicate session name: " + quote(full_name))
    1.11 +
    1.12          val path =
    1.13            entry.path match {
    1.14              case Some(p) => Path.explode(p)
    1.15 @@ -175,6 +180,7 @@
    1.16          val info =
    1.17            Session_Info(dir + path, full_name, entry.parent, entry.description,
    1.18              entry.options, thys, entry.files)
    1.19 +
    1.20          infos += info
    1.21        }
    1.22        catch {