Macro line

macro_rules! line {
    () => { ... };
}

Expands to the line number on which it was invoked.

With column! and file!, these macros provide debugging information for developers about the location within the source.

The expanded expression has type u32 and is 1-based, so the first line in each file evaluates to 1, the second to 2, etc. This is consistent with error messages by common compilers or popular editors. The returned line is not necessarily the line of the line! invocation itself, but rather the first macro invocation leading up to the invocation of the line! macro.

Examples

let current_line = line!();
println!("defined on line: {current_line}");