### Code ```Rust fn main() { format!("{}", 1); } ``` ### Current output ```Shell No errors or warnings ``` ### Desired output ```Shell warning: unused return value of `format!()` that must be used ``` ### Rationale and extra context The `format!()` macro could probably expand to code containing [`std::hint::must_use`](https://doc.rust-lang.org/stable/std/hint/fn.must_use.html). List of macros with similar issues: * `cfg!()` * `column!()`, `line!()`, `file!()`, `module_path!()` * `concat!()`, `stringify!()` * `env!()`, `option_env!()` * `format!()`, `format_args!()` * `include_bytes!()`, `include_str!()` * `matches!()` * `vec!()` * `pin::pin!()` ### Other cases _No response_ ### Rust Version ```Shell Nightly rust on playground: 1.81.0-nightly (2024-06-13 f1586001ace26df7cafe) ``` ### Anything else? _No response_