Setting a breakpoint inside a lamda that contains an object fails

[laeubi]

Assume the following code

package example;

import java.util.Optional;
import java.util.function.Consumer;

import org.eclipse.core.databinding.observable.sideeffect.ISideEffectFactory;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.databinding.swt.WidgetSideEffects;
import org.eclipse.swt.widgets.Composite;

public class NoBreakPoint {

	private Context context = new Context();

	public NoBreakPoint(Composite parent) {
		ISideEffectFactory factory = WidgetSideEffects.createFactory(parent);
		factory.create(context::getSample, sample -> new Consumer<Optional<String>>() {

			Optional<String> lastSample = Optional.empty();

			@Override
			public void accept(Optional<String> currentSample) {

				lastSample.ifPresent(System.out::println);
				currentSample.ifPresent(System.out::println);
				lastSample = currentSample;
			}
		});
	}

	private static final class Context {
		public Optional<String> getSample() {
			return Optional.of("An example"); //$NON-NLS-1$
		}
	}

	public void dummy1() {
		new Action() {

			@Override
			public void run() {
				super.run();
			}
		};
	}

}

• Now try to set a breakpoint in line 24 (lastSample.ifPresent(System.out::println);), it seems noting happens, but the Breakpoint view shows a breakpoint without a line number (in my real world code I get sett a breakpoint far away from the line i double clicked).
• Now double click on that one in the breakpoint view --> nothing happens.
• Now do the same on line 42 (super.run();)
• Everything works

Here is a video:

Peek.2024-09-27.09-35.mp4

Eclipse SDK

Version: 2024-12 (4.34)
Build id: I20240921-1800

[nettozahler]

Question: what is the best way to set up a proper example project having org.eclipse.core.*, org.eclipse.jface.*and org.eclipse.swt.* as dependencies so the above code compiles? Add some Eclipse projects to the classpath?

Anyhow - I did some mocking to make it compile and could reproduce it. I get the following error in the log:

org.eclipse.jface.text.BadLocationException: -1
	at org.eclipse.jface.text.TreeLineTracker.getLineInformation(TreeLineTracker.java:1153)
	at org.eclipse.jface.text.AbstractLineTracker.getLineInformation(AbstractLineTracker.java:228)
	at org.eclipse.jface.text.AbstractDocument.getLineInformation(AbstractDocument.java:873)
	at org.eclipse.core.internal.filebuffers.SynchronizableDocument.getLineInformation(SynchronizableDocument.java:290)
	at org.eclipse.jdt.internal.debug.ui.actions.ToggleBreakpointAdapter.doLineBreakpointToggle(ToggleBreakpointAdapter.java:529)
	at org.eclipse.jdt.internal.debug.ui.actions.ToggleBreakpointAdapter$1.run(ToggleBreakpointAdapter.java:213)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

[laeubi]

I extracted it from a real use-case, but usually a recent Eclipse as target platform should be enough, probably only the structure needs to be preserved, for example Action --> Runnable, Composite -> Object and so on...

[jukzi]

@nettozahler do you plan to work on this?

[nettozahler]

Well, I will do some debugging on this issue with reduced priority for me and see how far I can get. Maybe my Eclipse knowledge in jdt.debug is insufficient to find a solution in limited time. So I would not complain if anybody else is faster in finding a bufix :-)