1 C-variadic has been used on a non-foreign function.
3 Erroneous code example:
6 fn foo2(x: u8, ...) {} // error!
9 Only foreign functions can use C-variadic (`...`). It is used to give an
10 undefined number of parameters to a given function (like `printf` in C). The
11 equivalent in Rust would be to use macros directly.