40 lines
783 B
Rust
40 lines
783 B
Rust
// compile-flags:-Zverbose
|
|
|
|
#![allow(warnings)]
|
|
#![feature(rustc_attrs)]
|
|
|
|
use std::cell::Cell;
|
|
|
|
// Invoke in such a way that the callee knows:
|
|
//
|
|
// - 'a: 'x
|
|
//
|
|
// and it must prove that `T: 'x`. Callee passes along `T: 'a`.
|
|
fn twice<'a, F, T>(v: Cell<&'a ()>, value: T, mut f: F)
|
|
where
|
|
F: for<'x> FnMut(Option<Cell<&'a &'x ()>>, &T),
|
|
{
|
|
f(None, &value);
|
|
f(None, &value);
|
|
}
|
|
|
|
#[rustc_regions]
|
|
fn generic<T>(value: T) {
|
|
let cell = Cell::new(&());
|
|
twice(cell, value, |a, b| invoke(a, b));
|
|
}
|
|
|
|
#[rustc_regions]
|
|
fn generic_fail<'a, T>(cell: Cell<&'a ()>, value: T) {
|
|
twice(cell, value, |a, b| invoke(a, b));
|
|
//~^ ERROR the parameter type `T` may not live long enough
|
|
}
|
|
|
|
fn invoke<'a, 'x, T>(x: Option<Cell<&'x &'a ()>>, y: &T)
|
|
where
|
|
T: 'x,
|
|
{
|
|
}
|
|
|
|
fn main() {}
|