rust/tests/ui/variance/variance-trait-bounds.rs

39 lines
718 B
Rust

#![allow(dead_code)]
#![feature(rustc_attrs)]
// Check that bounds on type parameters (other than `Self`) do not
// influence variance.
trait Getter<T> {
fn get(&self) -> T;
}
trait Setter<T> {
fn get(&self, _: T);
}
#[rustc_variance]
struct TestStruct<U,T:Setter<U>> { //~ ERROR [U: +, T: +]
t: T, u: U
}
#[rustc_variance]
enum TestEnum<U,T:Setter<U>> { //~ ERROR [U: *, T: +]
//~^ ERROR: `U` is never used
Foo(T)
}
#[rustc_variance]
struct TestContraStruct<U,T:Setter<U>> { //~ ERROR [U: *, T: +]
//~^ ERROR: `U` is never used
t: T
}
#[rustc_variance]
struct TestBox<U,T:Getter<U>+Setter<U>> { //~ ERROR [U: *, T: +]
//~^ ERROR: `U` is never used
t: T
}
pub fn main() { }