Macro warn

macro_rules! warn {
    (target: $target:expr, { $( $($k:ident).+ = $val:expr ),*, }, $($arg:tt)+ ) => { ... };
    (target: $target:expr, { $( $($k:ident).+ = $val:expr ),* }, $($arg:tt)+ ) => { ... };
    (target: $target:expr, $( $($k:ident).+ = $val:expr ),*, ) => { ... };
    (target: $target:expr, $( $($k:ident).+ = $val:expr ),* ) => { ... };
    (target: $target:expr, $($arg:tt)+ ) => { ... };
    ({ $( $($k:ident).+ = $val:expr ),*, }, $($arg:tt)+ ) => { ... };
    ({ $( $($k:ident).+ = $val:expr ),* }, $($arg:tt)+ ) => { ... };
    ($( $($k:ident).+ = $val:expr ),*, ) => { ... };
    ($( $($k:ident).+ = $val:expr ),* ) => { ... };
    ($($arg:tt)+ ) => { ... };
}

Constructs an event at the warn level.

When both a message and fields are included, curly braces ({ and }) are used to delimit the list of fields from the format string for the message. A trailing comma on the final field is valid.

Examples

use tokio_trace::field;

let warn_description = "Invalid Input";
let input = &[0x27, 0x45];

warn!(input = field::debug(input), warning = warn_description);
warn!(
    target: "input_events",
    { warning = warn_description },
    "Received warning for input: {:?}", input,
);