syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// later proving the `Subtype(?0, ?1)` goal from the first relation.
context_before:     /// first time we've related these types, this only happens when
context_after:     cache: DelayedSet<(ty::Variance, I::Ty, I::Ty)>,