| // Test that the NLL solver cannot find a solution |
| // for `exists<R1> { forall<R1> { R2: R1 } }`. |
| // |
| // In this test, the impl should match `fn(T)` for some `T`, |
| // but we ask it to match `for<'a> fn(&'a ())`. Due to argument |
| // contravariance, this effectively requires a `T = &'b ()` where |
| // `forall<'a> { 'a: 'b }`. Therefore, we get an error. |
| // |
| // Note the use of `-Zno-leak-check` and `feature(nll)` here. These |
| // are presently required in order to skip the leak-check errors. |
| // |
| // c.f. Issue #57642. |
| // |
| // compile-flags:-Zno-leak-check |
| |
| #![feature(nll)] |
| |
| trait Y { |
| type F; |
| fn make_f() -> Self::F; |
| } |
| |
| impl<T> Y for fn(T) { |
| type F = fn(T); |
| |
| fn make_f() -> Self::F { |
| |_| {} |
| } |
| } |
| |
| fn main() { |
| let _x = <fn(&())>::make_f(); |
| //~^ higher-ranked subtype error |
| //~| higher-ranked subtype error |
| //~| higher-ranked subtype error |
| } |
