Recursion detection on render (avoids WSOD).

Patch is not easy to read, but you can apply it and compare with your own eyes the 2 files, you'll see I just added about 10 lines of code and re-indent 30 others (no big deal).

When I look at you patch I see that your method is almost the same, instead of using a global variable you use a static variable inside a function; but your algorithm remains the same.

I did not tested it yet, but I already have a note about it, you should not display the error message. In my case, this is not an error because the embedded view display the node with a different build mode that the full display, which help me placing node elements in the composite layout which are not displayed in the full page (so, by placing a block which displays a view which displays my own node is really what I want in this use case, this is not accidental).

I think maybe display the error message only if the user is site admin or if a site wide variable tells is set may be a bit less intrusive. Whatever is you choose, the message should never display to anonymous users (there is always the site wide setting that allow administrator to fully deactivate error messages for anonymous, but I don't think in this case your error message will be dropped).

I'll test it within the day.

Composite Layout only operates if the node is being viewed in 'full mode'. For any other build mode, Composite Layout won't do anything ... and the node won't be entered into the 'recursion list'.

In my case, the "Full node" is a build mode I want to be displayable inside my composite layout, I known that's weird, but it has a sense in this site.

There is at least one small change ... my patch doesn't 'clear' the flag after the node has been rendered.

True, and you should, because the content could be displayed more than one time in full mode on screen, it can be dumb to do that, but a site admin might want it (views can display nodes in full mode, blocks, the node page, and it can make sense).

EDIT:

Hmmm ... in my opinion, it is actually an error because if Composite Layout were to obey the user, they would get an infinite loop. If Composite Layout cannot do what the user asks, it should inform the user so the user can fix their content or content structure. I think failing silently (ie. not emitting an error message) is a bad idea.

Noting more logical than this, I agree, but in fact, I would do avoid recursions silently. In all cases, a non-owner for this node must not see the error message, in fact, any "normal" user should never see any of this kind of error message.

Let's just pretend that we should show the error message only for certain types of users ... how would you decide this? Show the error only for users with certain permissions ie. 'administer nodes'? show the error only for users with edit access to the node?

The check should be the same than the menu system one:

  if (composite_access('zones', 'update', $node)) {
    // Do my drupal_set_message( .. ) here.
  }

Please test this patch, pretty much the same as yours, except I added a reset parameter for the recursion check function, in order for the recursion part to unmark the node as being rendered at the end of recursion loop to ensure that if the same node is rendered twice on the same page, it will be.

EDIT: Works fine @home.

EDIT: It made me change the _composite_nodes_recursion_check() function signature by adding parameters, but hopefully I kept the backward compat so if this function was used elsewhere it'll continue to work as expected.

Np, pleased I could help:)