src/libsyntax_ext/trace_macros.rs

   1 use syntax::ext::base::{self, ExtCtxt};
   2 use syntax::symbol::kw;
   3 use syntax_pos::Span;
   4 use syntax::tokenstream::TokenTree;
   5
   6 pub fn expand_trace_macros(cx: &mut ExtCtxt<'_>,
   7                            sp: Span,
   8                            tt: &[TokenTree])
   9                            -> Box<dyn base::MacResult + 'static> {
  10     match tt {
  11         [TokenTree::Token(token)] if token.is_keyword(kw::True) => {
  12             cx.set_trace_macros(true);
  13         }
  14         [TokenTree::Token(token)] if token.is_keyword(kw::False) => {
  15             cx.set_trace_macros(false);
  16         }
  17         _ => cx.span_err(sp, "trace_macros! accepts only `true` or `false`"),
  18     }
  19
  20     base::DummyResult::any_valid(sp)
  21 }