syntax_data: {"ast_node_type":"other","tokens":[{"end":68,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// first time we've related these types, this only happens when
context_before:     /// constrain `?1` to `u32`. When using the cache entry from the
context_after:     /// later proving the `Subtype(?0, ?1)` goal from the first relation.