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//@ compile-flags: -Znext-solver
//@ check-pass
fn map<T: Default, U, F: FnOnce(T) -> U>(f: F) {
f(T::default());
}
fn main() {
map::<i32, _ /* ?U */, _ /* ?F */>(|x| x.to_string());
// PREVIOUSLY when confirming the `map` call, we register:
//
// (1.) ?F: FnOnce<(i32,)>
// (2.) <?F as FnOnce<(i32,)>>::Output projects-to ?U
//
// While (1.) is ambiguous, (2.) immediately gets processed
// and we infer `?U := <?F as FnOnce<(i32,)>>::Output`.
//
// Thus, the only pending obligation that remains is (1.).
// Since it is a trait obligation, we don't use it to deduce
// the closure signature, and we fail!
}
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