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|
// compile-flags:-Zverbose
#![allow(warnings)]
#![feature(rustc_attrs)]
use std::fmt::Debug;
fn with_signature<'a, T, F>(x: Box<T>, op: F) -> Box<dyn Debug + 'a>
where F: FnOnce(Box<T>) -> Box<dyn Debug + 'a>
{
op(x)
}
#[rustc_regions]
fn no_region<'a, T>(x: Box<T>) -> Box<dyn Debug + 'a>
where
T: Debug,
{
// Here, the closure winds up being required to prove that `T:
// 'a`. In principle, it could know that, except that it is
// type-checked in a fully generic way, and hence it winds up with
// a propagated requirement that `T: '_#2`, where `'_#2` appears
// in the return type. The caller makes the mapping from `'_#2` to
// `'a` (and subsequently reports an error).
with_signature(x, |y| y)
//~^ ERROR the parameter type `T` may not live long enough
}
fn correct_region<'a, T>(x: Box<T>) -> Box<Debug + 'a>
where
T: 'a + Debug,
{
x
}
fn wrong_region<'a, 'b, T>(x: Box<T>) -> Box<Debug + 'a>
where
T: 'b + Debug,
{
x
//~^ ERROR the parameter type `T` may not live long enough
}
fn outlives_region<'a, 'b, T>(x: Box<T>) -> Box<Debug + 'a>
where
T: 'b + Debug,
'b: 'a,
{
x
}
fn main() {}
|
