syntax_data: {"ast_node_type":"import","tokens":[{"end":70,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     // but the type parameters may cause a cycle with an upstream type
context_before:     // At this point, we know that the item of the ADT type is representable;
context_after:     let params_in_repr = tcx.params_in_repr(adt.did());