syntax_data: {"ast_node_type":"other","tokens":[{"end":82,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                                 // We also need to extend backwards for whitespace
context_before:                                 let sp = brace_span.shrink_to_hi().with_hi(expr_span.hi());
context_after:                                 sm.span_extend_prev_while(sp, |c| c.is_whitespace()).ok()