{"ast_node_type":"other","tokens":[{"end":77,"kind":"keyword","start":0,"text":"TypeMismatchSource::Arg"}]}
            TypeMismatchSource::Arg { call_expr, incompatible_arg: idx } => {
            // when this type diverged from our expectation.
                let hir::ExprKind::MethodCall(segment, _, args, _) = call_expr.kind else {