src/libsyntax_ext/log_syntax.rs

   1 use syntax::ext::base;
   2 use syntax::feature_gate;
   3 use syntax::print;
   4 use syntax::tokenstream;
   5 use syntax::symbol::sym;
   6 use syntax_pos;
   7
   8 pub fn expand_syntax_ext<'cx>(cx: &'cx mut base::ExtCtxt<'_>,
   9                               sp: syntax_pos::Span,
  10                               tts: &[tokenstream::TokenTree])
  11                               -> Box<dyn base::MacResult + 'cx> {
  12     if !cx.ecfg.enable_log_syntax() {
  13         feature_gate::emit_feature_err(&cx.parse_sess,
  14                                        sym::log_syntax,
  15                                        sp,
  16                                        feature_gate::GateIssue::Language,
  17                                        feature_gate::EXPLAIN_LOG_SYNTAX);
  18     }
  19
  20     println!("{}", print::pprust::tts_to_string(tts));
  21
  22     // any so that `log_syntax` can be invoked as an expression and item.
  23     base::DummyResult::any_valid(sp)
  24 }