rust/tests/run-make/unstable-feature-usage-metrics/lib.rs

#![feature(ascii_char)] // random lib feature
#![feature(box_patterns)] // random lang feature

// picked arbitrary unstable features, just need a random lib and lang feature, ideally ones that
// won't be stabilized any time soon so we don't have to update this test

fn main() {
    println!("foobar");
}