1 use syntax::ext::base::{self, ExtCtxt};
2 use syntax::feature_gate;
3 use syntax::symbol::{kw, sym};
5 use syntax::tokenstream::TokenTree;
7 pub fn expand_trace_macros(cx: &mut ExtCtxt<'_>,
10 -> Box<dyn base::MacResult + 'static> {
11 if !cx.ecfg.enable_trace_macros() {
12 feature_gate::emit_feature_err(&cx.parse_sess,
15 feature_gate::GateIssue::Language,
16 feature_gate::EXPLAIN_TRACE_MACROS);
19 match (tt.len(), tt.first()) {
20 (1, Some(&TokenTree::Token(_, ref tok))) if tok.is_keyword(kw::True) => {
21 cx.set_trace_macros(true);
23 (1, Some(&TokenTree::Token(_, ref tok))) if tok.is_keyword(kw::False) => {
24 cx.set_trace_macros(false);
26 _ => cx.span_err(sp, "trace_macros! accepts only `true` or `false`"),
29 base::DummyResult::any_valid(sp)