Struct FatalContext 

#[non_exhaustive]
pub struct FatalContext {
    pub cause: String,
    pub site: FatalSite,
}

Why the runtime is about to abort. Passed to the fatal handler.

Marked #[non_exhaustive] so future fields (e.g. a thread name, a stack-trace fragment) do not break existing match/struct-init expressions.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

cause: String

Best-effort message extracted from the panic payload.

site: FatalSite

Which runtime boundary caught it.