log::warn!

macro_rules! warn {
    ($($arg:tt)*) => { ... };
}

Unstable (rustc_private)

: use the crates.io log library instead

A convenience macro for logging at the warning log level.

Examples

#![feature(rustc_private)] #[macro_use] extern crate log; fn main() { let code = 3; warn!("you may like to know that a process exited with: {}", code); }

#[macro_use] extern crate log;

fn main() {
    let code = 3;
    warn!("you may like to know that a process exited with: {}", code);
}

Assumes the binary is main:

$ RUST_LOG=warn ./main
WARN:main: you may like to know that a process exited with: 3