syntax_data: {"ast_node_type":"other","tokens":[{"end":22,"kind":"keyword","start":0,"text":"tcx:"}]}
source_snippet:     tcx: TyCtxt<'tcx>,
context_before: fn insert_discr_cast_to_u128<'tcx>(
context_after:     local_decls: &mut IndexVec<Local, LocalDecl<'tcx>>,