Method downcast_ref

crates/core/src/error/error.rs:1052–1068

Downcast this error into a shared `&E` borrow. If this error is an `E`, then `Some(&E)` is returned. Otherwise, `None` is returned. If there are multiple instances of `E` in this error's chain, then the first (as encountered by [`Error::chain`]'s iteration order) is returned. # Example ``` # use wasmtime_internal_core as wasmtime; use wasmtime::error::{Error, OutOfMemory}; let error = Error::

(&self)

    /// );
    /// ```
    pub fn downcast_ref<E>(&self) -> Option<&E>
    where
        E: fmt::Display + fmt::Debug + Send + Sync + 'static,
    {
        self.error_ext_chain().find_map(|e| {
            let result = e.inner.downcast_ref::<E>();

            #[cfg(feature = "anyhow")]
            let result = result.or_else(|| {
                e.inner
                    .downcast_ref::<anyhow::Error>()
                    .and_then(|anyhow| anyhow.downcast_ref::<E>())
            });

            result
        })
    }

    /// Downcast this error into an exclusive `&mut E` borrow.
    ///