JOIN 'extra' fails with multiple value

I am trying to create a relationship handler for Profile2 which limits the relationship join to certain profile types. (This is analogous to a nodequeue relationship restricting to selected queues, or a flag relationship restricting to certain flags.)

I've subclasses the main views_handler_relationship class, and it looks like in the query() method, I just need to add an 'extra' to the join definition.

This is what I'm doing:

    $def['extra'] = array(
      array(
        //'table' => $this->definition['base'],  // turns out this is not needed
        'field' => 'type',
        'operator' => 'IN', // or this, strictly speaking
        'value' => array('main', 'foo'), // for debugging I'm hardcoding these;
          // normally they would come from option values.
      ),
    );

The PDO chokes on the query though, with this error:

PDOException: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''main', 'foo' WHERE (( (users.status <> '0') ))) subquery' at line 1: SELECT COUNT(*) AS expression FROM (SELECT 1 AS expression FROM {users} users LEFT JOIN {profile} profile_users ON users.uid = profile_users.uid AND profile_users.type IN :views_join_condition_0_0, :views_join_condition_0_1 WHERE (( (users.status <> :db_condition_placeholder_0) ))) subquery; Array ( [:db_condition_placeholder_0] => 0 [:views_join_condition_0_0] => main [:views_join_condition_0_1] => foo ) in views_plugin_pager->execute_count_query() (line 140 of /Users/joachim/Sites/7-drupal/sites/all/modules/views/plugins/views_plugin_pager.inc).

Clearly the problem is that the "IN views_join_condition_0_0, :views_join_condition_0_1" part needs parentheses around the placeholders.

I can see where in the view_join class this should be added (patch attached fixes this in one line).

However, this fix is no good. This is the error with the patch applied:

PDOException: SQLSTATE[HY093]: Invalid parameter number: number of bound variables does not match number of tokens: SELECT COUNT(*) AS expression FROM (SELECT 1 AS expression FROM {users} users LEFT JOIN {profile} profile_users ON users.uid = profile_users.uid AND profile_users.type IN ( :views_join_condition_0 ) WHERE (( (users.status <> :db_condition_placeholder_0) ))) subquery; Array ( [:db_condition_placeholder_0] => 0 [( :views_join_condition_0 )_0] => main [( :views_join_condition_0 )_1] => foo ) in views_plugin_pager->execute_count_query() (line 140 of /Users/joachim/Sites/7-drupal/sites/all/modules/views/plugins/views_plugin_pager.inc).

What's going on here is even weirder. The placeholders are broken -- [( :views_join_condition_0 )_0]

At the very end of build_join(), the view_join class calls this:

$select_query->addJoin($this->type, $right_table, $table['alias'], $condition, $arguments);

And at this point, the condition string still has only one placeholder, like this:

users.uid = profile_users.uid AND profile_users.type IN ( :views_join_condition_0 )

So something is going wrong in $select_query, which according to the build_join() header is a SelectQueryInterface -- I'm not entirely sure what that is.