{"ast_node_type":"variable","tokens":[{"end":50,"kind":"keyword","start":0,"text":"if"}]}
        if let None | Some("-mte") = mte_feature {
            features.iter().map(|s| &s[..]).rfind(|n| ["+mte", "-mte"].contains(&&n[..]));
            cx.tcx.dcx().emit_err(SanitizerMemtagRequiresMte);