syntax_data: {"ast_node_type":"impl","tokens":[{"end":84,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                     // If the trait ref of the associated item and the impl differs,
context_before:                 if let Some(impl_trait_ref) = self.parent_impl_trait_ref() {
context_after:                     // then we can't use the impl's identity args below, so