vendor/tracing-subscriber-0.3.18/src/macros.rs

#[cfg(feature = "std")]
macro_rules! try_lock {
    ($lock:expr) => {
        try_lock!($lock, else return)
    };
    ($lock:expr, else $els:expr) => {
        if let ::core::result::Result::Ok(l) = $lock {
            l
        } else if std::thread::panicking() {
            $els
        } else {
            panic!("lock poisoned")
        }
    };
}

macro_rules! feature {
    (
        #![$meta:meta]
        $($item:item)*
    ) => {
        $(
            #[cfg($meta)]
            #[cfg_attr(docsrs, doc(cfg($meta)))]
            $item
        )*
    }
}