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// 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 &isize 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: &isize) rebound the region &.
fn with<R, F>(f: F) -> R where F: FnOnce(&isize) -> R {
f(&3)
}
fn return_it<'a>() -> &'a isize {
with(|o| o)
//~^ ERROR lifetime may not live long enough
}
fn main() {
let x = return_it();
println!("foo={}", *x);
}
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