Paging is broken

Looks like this is due to comment_node_page_additions being called twice. Once by the comments module itself as it uses comment_node_view, the second time by commentsblock_block_view.

Now aside from slower processing, this wouldn't be an issue except...
Both functions call comment_node_page_additions, which in turn calls comment_get_thread, which - and this is the key - extends PagerDefault in it's $query object.

PagerDefault lives inside pager.inc and each time it is called, (here is where I'm a little fuzzy, so could be wrong) it registers that caller as a unique paging element on the page. Because it is called twice the pager things the second call is a second element on the page and as a result it never picks up the first element's page URL - since it is looking for a second one!

To confirm this, you can switch the URL from ?page=1 to ?page=0,1 and voila - paging "works"!

I've attached two screenshots showing the elements being picked up and the double-calls. The second time you can see in the URL I've added the second element - and that time it worked to load the second page of comments.

Thanks to help from http://drupal.stackexchange.com/a/27406/6581 I've got a patch.

I don't think this would break anything comments-wise, but it needs testing by those who choose "Yes" to the configuration option of "Display comment form only?" and use a View to list comments.

A quick search just of contrib module we are using for our(large-ish) site turned up uses of hook_module_implementation_alter by:

• entity - "Moves the hook_entity_info_alter() implementation to the bottom so it is invoked after all modules relying on the entity API. That way we ensure to run last and clear the field-info cache after the others added in their bundle information."
• pathauto - "Adds pathauto support for core modules."
• token - "Adds missing token support for core modules."

Not feeling like that commentsblock module is quite on the same playing field as these practically core "contrib" modules.

However, I looked at using the example shown in the API docs for hook_module_implements_alter() which is:

function hook_module_implements_alter(&$implementations, $hook) {
  if ($hook == 'rdf_mapping') {
    // Move my_module_rdf_mapping() to the end of the list. module_implements()
    // iterates through $implementations with a foreach loop which PHP iterates
    // in the order that the items were added, so to move an item to the end of
    // the array, we remove it and then add it.
    $group = $implementations['my_module'];
    unset($implementations['my_module']);
    $implementations['my_module'] = $group;
  }
}

Trouble is, pushing comment_node_view() to last in the list of executed hooks doesn't help if hook_node_view() is being called in it's entirety before hook_block_view() which commentsblock uses.

Without Views (sorry for the late reply).

I think the patch in #2 is the fix. We set the comment limit to 300 on our site so that we effectively never have paging.

Works for me!