syntax_data: {"ast_node_type":"other","tokens":[{"end":43,"kind":"keyword","start":0,"text":"self.param_env,"}]}
source_snippet:                             self.param_env,
context_before:                             self.cx(),
context_after:                             ty::Binder::dummy(ty::PredicateKind::Subtype(ty::SubtypePredicate {