syntax_data: {"ast_node_type":"other","tokens":[{"end":62,"kind":"keyword","start":0,"text":"pattern_arena:"}]}
source_snippet:     pattern_arena: &'p TypedArena<DeconstructedPat<'p, 'tcx>>,
context_before:     let_source: LetSource,
context_after:     dropless_arena: &'p DroplessArena,