structopt does not seem to use unsafe code, which is very good :)

To prevent this from ever happening, add following line to the top:

#![forbid(unsafe_code)]

of https://github.com/TeXitoi/structopt/blob/master/src/lib.rs
and https://github.com/TeXitoi/structopt/blob/master/structopt-derive/src/lib.rs

This will make the package green in
https://github.com/rust-secure-code/cargo-geiger