syntax_data: {"ast_node_type":"other","tokens":[{"end":78,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                 // Dummy span for the `def_site` means it's an external macro.
context_before:             ExpnKind::Macro(MacroKind::Bang, _) => {
context_after:                 expn_data.def_site.is_dummy() || sm.is_imported(expn_data.def_site)