syntax_data: {"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":"expected_trait_ref:"}]}
source_snippet:                     expected_trait_ref: obligation_trait_ref,
context_before:                 SelectionError::SignatureMismatch(Box::new(SignatureMismatchData {
context_after:                     found_trait_ref,