{"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"let"}]}
            let var_ty = self.resolve_vars_if_possible(var_ty);
        if let Err(mut err) = self.demand_eqtype_pat_diag(span, var_ty, ty, ti) {
            let msg = format!("first introduced with type `{var_ty}` here");