syntax_data: {"ast_node_type":"variable","tokens":[{"end":41,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let mut opt_old_mode_span = None;
context_before:         // patterns do not. Only track binding mode changes if a ref type is in the adjustments.
context_after:         if let Some(s) = &mut self.rust_2024_migration