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trait StaticDefaultRef: 'static {
fn default_ref() -> &'static Self;
}
impl StaticDefaultRef for str {
fn default_ref() -> &'static str {
""
}
}
fn into_impl(x: &str) -> &(impl ?Sized + AsRef<str> + StaticDefaultRef + '_) {
x
}
fn extend_lifetime<'a>(x: &'a str) -> &'static str {
let t = into_impl(x);
helper(|_| t) //~ ERROR lifetime may not live long enough
}
fn helper<T: ?Sized + AsRef<str> + StaticDefaultRef>(f: impl FnOnce(&T) -> &T) -> &'static str {
f(T::default_ref()).as_ref()
}
fn main() {
let r;
{
let x = String::from("Hello World?");
r = extend_lifetime(&x);
}
println!("{}", r);
}
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