Function rust_backtrace 

pub fn rust_backtrace() -> RustBacktrace

The effective backtrace setting for the current thread.

Returns the thread-local override set via set_rust_backtrace_override if present; otherwise the value derived from RUST_LIB_BACKTRACE then RUST_BACKTRACE. Like std, the environment is read once and cached — only an override can change the result afterwards.