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//! Test for issue <github.com/rust-lang/rust/issues/30904>
//! Related to higher-ranked lifetime inference with unboxed closures and FnOnce.
#![feature(fn_traits, unboxed_closures)]
fn test<F: for<'x> FnOnce<(&'x str,)>>(_: F) {}
struct Compose<F, G>(F, G);
impl<T, F, G> FnOnce<(T,)> for Compose<F, G>
where
F: FnOnce<(T,)>,
G: FnOnce<(F::Output,)>,
{
type Output = G::Output;
extern "rust-call" fn call_once(self, (x,): (T,)) -> G::Output {
(self.1)((self.0)(x))
}
}
struct Str<'a>(&'a str);
fn mk_str<'a>(s: &'a str) -> Str<'a> {
Str(s)
}
fn main() {
let _: for<'a> fn(&'a str) -> Str<'a> = mk_str;
let _: for<'a> fn(&'a str) -> Str<'a> = Str;
//~^ ERROR: mismatched types
test(|_: &str| {});
test(mk_str);
test(Str);
test(Compose(|_: &str| {}, |_| {}));
test(Compose(mk_str, |_| {}));
test(Compose(Str, |_| {}));
}
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