Bug 162655 [Undo] [IDE] - Undoing a delete should check for existence of resources to be restored
N20061027. - I deleted two projects (along with their content). I read the warning that undo delete cannot restore the content and said "OK." - Then I checked out those same projects from HEAD. - Then I selected "Undo Delete Resources." This overwrote my code with empty projects. I think that "Undo Delete Resources" should become invalid if the resources exist again, because you'll end up replacing content without keeping a backup.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/undo/CopyResourcesOperation.java
}
		
		setResourceDescriptions((ResourceDescription[]) overwrittenResources
				.toArray(new ResourceDescription[overwrittenResources.size()]));
		
		
		setTargetResources((IResource[]) resourcesAtDestination
				.toArray(new IResource[resourcesAtDestination.size()]));
		monitor.done();
	}
	/*
	 * (non-Javadoc)
	 * 
	 * This implementation deletes the previously made copies and restores any
	 * resources that were overwritten by the copy.
	 * 
	 * @see org.eclipse.ui.ide.undo.AbstractWorkspaceOperation#doUndo(org.eclipse.core.runtime.IProgressMonitor,
	 *      org.eclipse.core.runtime.IAdaptable)
	 */
	protected void doUndo(IProgressMonitor monitor, IAdaptable uiInfo)
			throws CoreException {
		monitor.beginTask("", 2); 
		monitor
				.setTaskName(UndoMessages.AbstractResourcesOperation_CopyingResourcesProgress);
		
		WorkspaceUndoUtil.delete(resources, new SubProgressMonitor(monitor, 1),
				uiInfo, true);
		
		WorkspaceUndoUtil.recreate(resourceDescriptions,
				new SubProgressMonitor(monitor, 1), uiInfo);