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#![feature(unboxed_closures)]
// Test for projection cache. We should be able to project distinct
// lifetimes from `foo` as we reinstantiate it multiple times, but not
// if we do it just once. In this variant, the region `'a` is used in
// an invariant position, which affects the results.
// revisions: ok oneuse transmute krisskross
//[ok] check-pass
#![allow(dead_code, unused_variables)]
use std::marker::PhantomData;
struct Type<'a> {
// Invariant
data: PhantomData<fn(&'a u32) -> &'a u32>,
}
fn foo<'a>() -> Type<'a> {
loop {}
}
fn bar<T>(t: T, x: T::Output) -> T::Output
where
T: FnOnce<()>,
{
t()
}
#[cfg(ok)] // two instantiations: OK
fn baz<'a, 'b>(x: Type<'a>, y: Type<'b>) -> (Type<'a>, Type<'b>) {
let a = bar(foo, x);
let b = bar(foo, y);
(a, b)
}
#[cfg(oneuse)] // one instantiation: BAD
fn baz<'a, 'b>(x: Type<'a>, y: Type<'b>) -> (Type<'a>, Type<'b>) {
let f = foo; // <-- No consistent type can be inferred for `f` here.
let a = bar(f, x);
//[oneuse]~^ ERROR lifetime may not live long enough
//[oneuse]~| ERROR lifetime may not live long enough
let b = bar(f, y);
(a, b)
}
#[cfg(transmute)] // one instantiations: BAD
fn baz<'a, 'b>(x: Type<'a>) -> Type<'static> {
// Cannot instantiate `foo` with any lifetime other than `'a`,
// since it is provided as input.
bar(foo, x) //[transmute]~ ERROR lifetime may not live long enough
}
#[cfg(krisskross)] // two instantiations, mixing and matching: BAD
fn transmute<'a, 'b>(x: Type<'a>, y: Type<'b>) -> (Type<'a>, Type<'b>) {
let a = bar(foo, y);
let b = bar(foo, x);
(a, b)
//[krisskross]~^ ERROR lifetime may not live long enough
//[krisskross]~| ERROR lifetime may not live long enough
}
fn main() {}
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