#![allow(unused_variables)] #![deny(dead_code)] #![feature(rustc_attrs)] struct Foo; trait Bar { fn bar1(&self); fn bar2(&self) { self.bar1(); } } impl Bar for Foo { fn bar1(&self) { live_fn(); } } fn live_fn() {} fn dead_fn() {} //~ ERROR: function `dead_fn` is never used fn used_fn() {} #[rustc_main] fn actual_main() { used_fn(); let foo = Foo; foo.bar2(); } // this is not main fn main() { //~ ERROR: function `main` is never used dead_fn(); }