syntax_data: {"ast_node_type":"other","tokens":[{"end":26,"kind":"keyword","start":0,"text":"let_source:"}]}
source_snippet:     let_source: LetSource,
context_before:     lint_level: HirId,
context_after:     pattern_arena: &'p TypedArena<DeconstructedPat<'p, 'tcx>>,