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// ICE failed to resolve instance for <fn() -> impl MyFnOnce ...
// issue: rust-lang/rust#105488
//@ build-fail
//~^^^ ERROR overflow evaluating the requirement `fn() -> impl MyFnOnce
pub trait MyFnOnce {
type Output;
fn call_my_fn_once(self) -> Self::Output;
}
pub struct WrapFnOnce<F>(F);
impl<F: FnOnce() -> D, D: MyFnOnce> MyFnOnce for WrapFnOnce<F> {
type Output = D::Output;
fn call_my_fn_once(self) -> Self::Output {
D::call_my_fn_once(self.0())
}
}
impl<F: FnOnce() -> D, D: MyFnOnce> MyFnOnce for F {
type Output = D::Output;
fn call_my_fn_once(self) -> Self::Output {
D::call_my_fn_once(self())
}
}
pub fn my_fn_1() -> impl MyFnOnce {
my_fn_2
}
pub fn my_fn_2() -> impl MyFnOnce {
WrapFnOnce(my_fn_1)
}
fn main() {
let v = my_fn_1();
let _ = v.call_my_fn_once();
}
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