syntax_data: {"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // from a foreign crate; we could also take into account `-Zmacro-backtrace`,
context_before:             // FIXME: This does limit the usefulness of the error when the macro is
context_after:             // which doesn't redact this span (but that would mean passing in even more