Macro show_warning 

macro_rules! show_warning {
    ($($args:tt)+) => { ... };
}

Print a warning message to stderr.

Takes format!-compatible input and prepends it with the current utility’s name and “warning: “ before printing to stderr.

Examples

// outputs <name>: warning: Couldn't apply foo to bar
show_warning!("Couldn't apply {} to {}", "foo", "bar");