{"ast_node_type":"variable","tokens":[{"end":52,"kind":"keyword","start":0,"text":"let"}]}
            let mut err = if !allow_experimental_reg
        let Some((_, feature)) = supported_tys.iter().find(|&&(t, _)| t == asm_ty) else {
                && reg_class.supported_types(asm_arch, true).iter().any(|&(t, _)| t == asm_ty)