Migrated from http://lampsvn.epfl.ch/trac/scala/ticket/164
Reporter dubochet
Copy-pasting a bunch of type members multiple times causes following crash.

java.lang.AssertionError: assertion failed: ClassEnv
at scala.Predef$.assert(Predef.scala:96)
at scala.tools.nsc.symtab.Symbols$Symbol.info(Symbols.scala:450)
at scala.tools.editor.Typers0$FileImpl$class.scala$tools$editor$Typers0$$save(Typers0.scala:777)
at scala.tools.eclipse.Driver$Project$File.scala$tools$editor$Typers0$$save(Driver.scala:13)
at scala.tools.editor.Typers0$FileImpl$class.scala$tools$editor$Typers0$FileImpl$$save(Typers0.scala:767)
at scala.tools.editor.Typers0$FileImpl$$anonfun$30.apply(Typers0.scala:794)
at scala.tools.editor.Typers0$FileImpl$$anonfun$30.apply(Typers0.scala:794)
at scala.List.foreach(List.scala:730)
at scala.tools.editor.Typers0$FileImpl$class.scala$tools$editor$Typers0$$save(Typers0.scala:794)
at scala.tools.eclipse.Driver$Project$File.scala$tools$editor$Typers0$$save(Driver.scala:13)
at scala.tools.editor.Typers0$FileImpl$class.scala$tools$editor$Typers0$FileImpl$$save(Typers0.scala:767)
at scala.tools.editor.Typers0$FileImpl$$anonfun$35.apply(Typers0.scala:832)
at scala.tools.editor.Typers0$FileImpl$$anonfun$35.apply(Typers0.scala:832)
at scala.List.foreach(List.scala:730)
at scala.tools.editor.Typers0$FileImpl$class.resetSaved(Typers0.scala:832)
at scala.tools.eclipse.Driver$Project$File.resetSaved(Driver.scala:13)
at scala.tools.editor.TypersPresentations$ProjectImpl$FileImpl$$anonfun$7.apply(TypersPresentations.scala:94)
at scala.tools.editor.TypersPresentations$ProjectImpl$FileImpl$$anonfun$7.apply(TypersPresentations.scala:94)
at lampion.eclipse.UIPlugin$ProjectImpl$$anon$6.run(UIPlugin.scala:400)
at org.eclipse.ui.internal.UILockListener.doPendingWork(UILockListener.java:155)
at org.eclipse.ui.internal.UISynchronizer$2.run(UISynchronizer.java:126)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:123)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3212)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2956)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2389)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2353)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2219)
at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:466)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:289)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:461)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:106)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:153)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:106)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:76)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:363)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:176)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:504)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:443)
at org.eclipse.equinox.launcher.Main.run(Main.java:1169)