pub fn panicking() -> bool
Determines whether the current thread is unwinding because of panic.
A common use of this feature is to poison shared resources when writing
unsafe code, by checking
panicking when the
drop is called.
This is usually not needed when writing safe code, as
already poison themselves when a thread panics while holding the lock.
This can also be used in multithreaded applications, in order to send a message to other threads warning that a thread has panicked (e.g., for monitoring purposes).