Index: src/org/aspectj/weaver/bcel/BcelWeaver.java
===================================================================
RCS file: /home/technology/org.aspectj/modules/weaver/src/org/aspectj/weaver/bcel/BcelWeaver.java,v
retrieving revision 1.53
diff -u -r1.53 BcelWeaver.java
--- src/org/aspectj/weaver/bcel/BcelWeaver.java	17 May 2005 08:29:18 -0000	1.53
+++ src/org/aspectj/weaver/bcel/BcelWeaver.java	6 Jun 2005 09:45:56 -0000
@@ -974,6 +974,18 @@
 			UnwovenClassFile clf = (UnwovenClassFile) iter.next();
             typesToProcess.add(clf.getClassName());
         }
+        
+    	String duplicate = containsDuplicates(typesToProcess);
+    	if (duplicate != null){
+    		System.err.println("Error: duplicate type \"" + duplicate + "\"");
+    		System.err.println();
+    		System.err.println("This may be caused by bug 98120 in jdt.");
+    		System.err.println("If so the workaround is to not put dollar signs in type names, "
+    	    + "If there wasn't\na dollar sign in the duplicate type please report this as a bug in AspectJ"
+    		+ " and\ninclude this message in the bug report.");
+    		return new ArrayList();
+    	}
+        
         while (typesToProcess.size()>0) {
             weaveParentsFor(typesToProcess,(String)typesToProcess.get(0));
         }  
@@ -1489,4 +1501,20 @@
     public World getWorld() {
         return world;
     }
+    
+    public static String containsDuplicates(List l){
+    	// this method should be somewhere else
+    	// returns the first duplicate object in l
+    	for (int i = 0; i < l.size(); i++){
+    		String s1 = (String)l.get(i);
+    		for (int j = i+1; j < l.size(); j++){
+    			String s2 = (String)l.get(j);
+    			if (s1.equals(s2)){
+    				return s1;
+    			}
+    		}
+    	}
+    	return null;
+    }
+    
 }