// Copyright 2012 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. // Ensure that you cannot use generic types to return a region outside // of its bound. Here, in the `return_it()` fn, we call with() but // with R bound to &int from the return_it. Meanwhile, with() // provides a value that is only good within its own stack frame. This // used to successfully compile because we failed to account for the // fact that fn(x: &int) rebound the region &. fn with(f: F) -> R where F: FnOnce(&int) -> R { f(&3) } fn return_it<'a>() -> &'a int { with(|o| o) //~^ ERROR cannot infer } fn main() { let x = return_it(); println!("foo={}", *x); }