syntax_data: {"ast_node_type":"variable","tokens":[{"end":66,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let trait_def_id = tcx.trait_id_of_impl(impl_def_id).unwrap();
context_before: ) -> Result<LeafDef, ErrorGuaranteed> {
context_after:     let trait_def = tcx.trait_def(trait_def_id);