syntax_data: {"ast_node_type":"other","tokens":[{"end":48,"kind":"keyword","start":0,"text":"self.infcx.enter_forall(b,"}]}
source_snippet:                 self.infcx.enter_forall(b, |b| {
context_before:             ty::Covariant => {
context_after:                     let a = self.infcx.instantiate_binder_with_infer(a);