rustc/tests/ui/liveness/liveness-forgot-ret.rs

fn god_exists(a: isize) -> bool { return god_exists(a); }
//~^ WARN function cannot return without recursing

fn f(a: isize) -> isize { if god_exists(a) { return 5; }; }
//~^ ERROR mismatched types

fn main() { f(12); }