{"ast_node_type":"other","tokens":[{"end":68,"kind":"keyword","start":0,"text":"//"}]}
    // properly (see `TyLoweringContext::select_associated_type()`).
    // free `BoundVar`s that need to be shifted and only `TyLoweringContext` knows how to do that
    mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>,