syntax_data: {"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"DefineOpaqueTypes::Yes,"}]}
source_snippet:                                     DefineOpaqueTypes::Yes,
context_before:                                 self.infcx.at(&obligation.cause, obligation.param_env).eq_trace(
context_after:                                     ToTrace::to_trace(