syntax_data: {"ast_node_type":"other","tokens":[{"end":94,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                     // predicates we insert in the `explicit_predicates_of` query for RPITITs.
context_before:                     // lifetimes because they're already "linked" by the bidirectional outlives
context_after:                     let mut mapping = FxHashMap::default();