| error[E0282]: type annotations needed | |
| --> $DIR/sort_by_key.rs:3:9 | |
| | | |
| LL | lst.sort_by_key(|&(v, _)| v.iter().sum()); | |
| | ^^^^^^^^^^^ cannot infer type for type parameter `K` declared on the associated function `sort_by_key` | |
| | | |
| help: consider specifying the type argument in the method call | |
| | | |
| LL | lst.sort_by_key(|&(v, _)| v.iter().sum::<S>()); | |
| | ^^^^^ | |
| error: aborting due to previous error | |
| For more information about this error, try `rustc --explain E0282`. |