{"ast_node_type":"variable","tokens":[{"end":97,"kind":"keyword","start":0,"text":"let"}]}
        let Some(idx) = self.generics.as_ref().and_then(|g| g.type_or_const_param_idx(it)) else {
        let it = from_placeholder_idx(self.db, idx);
            not_supported!("missing idx in generics");