Function secp256k1_sys::rustsecp256k1_v0_6_1_default_error_callback_fn

#[no_mangle]
pub unsafe extern "C" fn rustsecp256k1_v0_6_1_default_error_callback_fn(
    message: *const c_char,
    _data: *mut c_void
)

This function is an override for the C function, this is the an edited version of the original description:

A callback function to be called when an internal consistency check fails. This will cause a panic.

This can only trigger in case of a hardware failure, miscompilation, memory corruption, serious bug in the library, or other error would can otherwise result in undefined behaviour. It will not trigger due to mere incorrect usage of the API (see secp256k1_default_illegal_callback_fn for that). After this callback returns, anything may happen, including crashing.

See also secp256k1_default_illegal_callback_fn.