Rust · Macro

todo!

todo! marks unfinished Rust code and helps a prototype pass type analysis. It always panics when execution reaches it, with either its default or a custom message.

Last updated 2 November 2026

Since

1.40.0

macro_rules! todo {
    () => { ... };
    ($($arg:tt)+) => { ... };
}

Source: todo in std - Rust. Checked 2026-11-03.