syntax_data: {"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     // using `PartialEq::eq` in this scenario in the past.)
context_before:     // error, because that's never worked, due to compiler
context_after:     let partial_eq_trait_id = tcx.require_lang_item(hir::LangItem::PartialEq, DUMMY_SP);