| // Copyright 2015 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| trait Foo<A> { |
| fn get(&self, A: &A) { } |
| } |
| |
| trait Bar { |
| type Out; |
| } |
| |
| impl<T> Foo<T> for [isize;0] { |
| // OK, T is used in `Foo<T>`. |
| } |
| |
| impl<T,U> Foo<T> for [isize;1] { |
| //~^ ERROR the type parameter `U` is not constrained |
| } |
| |
| impl<T,U> Foo<T> for [isize;2] where T : Bar<Out=U> { |
| // OK, `U` is now constrained by the output type parameter. |
| } |
| |
| impl<T:Bar<Out=U>,U> Foo<T> for [isize;3] { |
| // OK, same as above but written differently. |
| } |
| |
| impl<T,U> Foo<T> for U { |
| // OK, T, U are used everywhere. Note that the coherence check |
| // hasn't executed yet, so no errors about overlap. |
| } |
| |
| impl<T,U> Bar for T { |
| //~^ ERROR the type parameter `U` is not constrained |
| |
| type Out = U; |
| |
| // Using `U` in an associated type within the impl is not good enough! |
| } |
| |
| impl<T,U> Bar for T |
| where T : Bar<Out=U> |
| { |
| //~^^^ ERROR the type parameter `U` is not constrained |
| |
| // This crafty self-referential attempt is still no good. |
| } |
| |
| impl<T,U,V> Foo<T> for T |
| where (T,U): Bar<Out=V> |
| { |
| //~^^^ ERROR the type parameter `U` is not constrained |
| //~| ERROR the type parameter `V` is not constrained |
| |
| // Here, `V` is bound by an output type parameter, but the inputs |
| // are not themselves constrained. |
| } |
| |
| impl<T,U,V> Foo<(T,U)> for T |
| where (T,U): Bar<Out=V> |
| { |
| // As above, but both T and U ARE constrained. |
| } |
| |
| fn main() { } |