syntax_data: {"ast_node_type":"other","tokens":[{"end":30,"kind":"keyword","start":0,"text":"user_ty:"}]}
source_snippet:                 user_ty: None,
context_before:                 ty: Ty::new_imm_ref(tcx, tcx.lifetimes.re_erased, var_ty),
context_after:                 source_info,