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#![allow(warnings)]
fn closure_expecting_bound<F>(_: F)
where
F: FnOnce(&u32),
{
}
fn closure_expecting_free<'a, F>(_: F)
where
F: FnOnce(&'a u32),
{
}
fn expect_bound_supply_nothing() {
// Because `x` is inferred to have a bound region, we cannot allow
// it to escape into `f`:
let mut f: Option<&u32> = None;
closure_expecting_bound(|x| {
f = Some(x); //~ ERROR borrowed data escapes outside of closure
});
}
fn expect_bound_supply_bound() {
// Because `x` is inferred to have a bound region, we cannot allow
// it to escape into `f`, even with an explicit type annotation on
// closure:
let mut f: Option<&u32> = None;
closure_expecting_bound(|x: &u32| {
f = Some(x); //~ ERROR borrowed data escapes outside of closure
});
}
fn expect_free_supply_nothing() {
let mut f: Option<&u32> = None;
closure_expecting_free(|x| f = Some(x)); // OK
}
fn expect_free_supply_bound() {
let mut f: Option<&u32> = None;
// Here, even though the annotation `&u32` could be seen as being
// bound in the closure, we permit it to be defined as a free
// region (which is inferred to something in the fn body).
closure_expecting_free(|x: &u32| f = Some(x)); // OK
}
fn expect_free_supply_named<'x>() {
let mut f: Option<&u32> = None;
// Here, even though the annotation `&u32` could be seen as being
// bound in the closure, we permit it to be defined as a free
// region (which is inferred to something in the fn body).
closure_expecting_free(|x: &'x u32| f = Some(x)); // OK
}
fn main() {}
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