Below are three files: TreeInfo.java, TreeScanner.java and Tree.java.
If they are compiled with
	javac p/Tree.java p/TreeScanner.java p/TreeInfo.java
the compilation succeeds.

If they are compiled with 
	javac p/TreeInfo.java p/TreeScanner.java p/Tree.java
you get the following error:

p/TreeScanner.java:9: unreported exception java.lang.Throwable; must be caught or declared to be thrown
	if(tree!=null) tree.accept(this);
                                  ^
1 error



------Tree.java--------------
package p;

public abstract class Tree {

    /** Visit this tree with a given visitor.
     */
    public abstract <E extends Throwable> void accept(Visitor<E> v) throws E;


    /** A generic visitor class for trees.
     */
    public static abstract class Visitor<E extends Throwable> {
	public void visitTree(Tree that)                   throws E { assert false; }
    }
}


------TreeInfo.java----------
package p;
import p.Tree.*;

public class TreeInfo {

    public static void declarationFor(final Tree tree) {
	class DeclScanner extends TreeScanner<Error> {
            public void scan(Tree tree) {
            }
	}
	DeclScanner s = new DeclScanner();
	tree.accept(s);
    }
}


------TreeScanner.java-------
package p;
import p.Tree.*;

public class TreeScanner<E extends Throwable> extends Visitor<E> {

    /** Visitor method: Scan a single node.
     */
    public void scan(Tree tree) throws E {
	if(tree!=null) tree.accept(this);
    }
}
Posted Date : 2005-09-20 17:14:48.0

N/A

The problem is apparently that attribution and flow analysis is mixed with
erasure in main.JavaCompiler.compile in the while(todo.nonEmpty()) loop.
The work should be split into two: first a loop to do attribution and flow
analysis, then a loop to translate the types.

This analysis is confirmed by disabling the second part of the loop.

  xxxxx@xxxxx   2004-11-24 08:24:54 GMT

A more correct solution would be to make erasure "non-destructive".

  xxxxx@xxxxx   2005-05-18 02:16:13 GMT

Extracted "flow" phase out of "desugar"
  xxxxx@xxxxx   2005-06-23 23:23:49 GMT
Posted Date : 2005-06-23 23:23:49.0