| // compile-flags:-Zborrowck=mir -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() {} |