Maybe this could have a macro:

```rust
macro_rules! fmt_strs {
    ($result: expr; $($name: expr: ([$($field_name: expr),*], $span: expr, $dump: expr)),* => {
         {
             $( ($result).fmt_strs.insert($name, (vec!($($field_name),*), $span, $dump); )*
         }
    }
}

fmt_str! { result;
    "variable": (["id", "name", ...], true, true),
    // ...
}
```