UnwindDetector.rs

/// Guards a scope against unwinding, calling a handler if unwinding occurs.
///
/// - Handler gets no panic info; limited to `Fn()`
/// - Not reentrant; handler panics may cause program abort
/// - Intended for single scope; don't store or share
/// - Ineffective with panic=abort
pub struct UnwindDetector<T: Fn()> {
    handler: T,
}

impl<T: Fn()> UnwindDetector<T> {
    /// Creates a new detector. Handler runs if dropped during panic.
    pub fn new(handler: T) -> Self {
        Self { handler }
    }
}

impl<T: Fn()> Drop for UnwindDetector<T> {
    fn drop(&mut self) {
        if std::thread::panicking() {
            (self.handler)()
        }
    }
}