syntax_data: {"ast_node_type":"other","tokens":[{"end":83,"kind":"keyword","start":0,"text":"tcx.require_lang_item(LangItem::Future,"}]}
source_snippet:                     tcx.require_lang_item(LangItem::Future, obligation.cause.span);
context_before:                 let future_trait_def_id =
context_after:                 let placeholder_output_ty = self.infcx.enter_forall_and_leak_universe(sig.output());