Macro diesel::enable_multi_table_joins

macro_rules! enable_multi_table_joins {
    ($left_mod:ident, $right_mod:ident) => { ... };
}

Allow two tables which are otherwise unrelated to be used together in a multi-table join. This macro only needs to be invoked when the two tables don't have an association between them (e.g. parent to grandchild)

Example

// This would be required to do `users.inner_join(posts.inner_join(comments))`
// if there were an association between users and posts, and an association
// between posts and comments, but no association between users and comments
enable_multi_table_joins!(users, comments);