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use syntax::ext::base::{self, ExtCtxt};
use syntax::feature_gate;
use syntax::symbol::{keywords, sym};
use syntax_pos::Span;
use syntax::tokenstream::TokenTree;
pub fn expand_trace_macros(cx: &mut ExtCtxt<'_>,
sp: Span,
tt: &[TokenTree])
-> Box<dyn base::MacResult + 'static> {
if !cx.ecfg.enable_trace_macros() {
feature_gate::emit_feature_err(&cx.parse_sess,
sym::trace_macros,
sp,
feature_gate::GateIssue::Language,
feature_gate::EXPLAIN_TRACE_MACROS);
}
match (tt.len(), tt.first()) {
(1, Some(&TokenTree::Token(_, ref tok))) if tok.is_keyword(keywords::True) => {
cx.set_trace_macros(true);
}
(1, Some(&TokenTree::Token(_, ref tok))) if tok.is_keyword(keywords::False) => {
cx.set_trace_macros(false);
}
_ => cx.span_err(sp, "trace_macros! accepts only `true` or `false`"),
}
base::DummyResult::any_valid(sp)
}
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