syntax_data: {"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // the assert below ensures that it doesn't happen.
context_before:         // The inserted dummy data can only be potentially accessed by nested `alloc_ctxt` calls,
context_after:         let ctxt = SyntaxContext::from_usize(self.syntax_context_data.len());