rust/src/test/compile-fail/coherence-default-trait-impl.rs
Aaron Turon bc33dd7ac4 Provide overlapping types for coherence errors
Currently, a coherence error based on overlapping impls simply mentions
the trait, and points to the two conflicting impls:

```
error: conflicting implementations for trait `Foo`
```

With this commit, the error will include all input types to the
trait (including the `Self` type) after unification between the
overlapping impls. In other words, the error message will provide
feedback with full type details, like:

```
error: conflicting implementations of trait `Foo<u32>` for type `u8`:
```

When the `Self` type for the two impls unify to an inference variable,
it is elided in the output, since "for type `_`" is just noise in that
case.

Closes #23980
2015-12-16 09:47:23 -08:00

31 lines
894 B
Rust

// 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.
#![feature(optin_builtin_traits)]
trait MyTrait {}
impl MyTrait for .. {}
impl MyTrait for .. {}
//~^ ERROR conflicting implementations of trait `MyTrait`
trait MySafeTrait {}
unsafe impl MySafeTrait for .. {}
//~^ ERROR implementing the trait `MySafeTrait` is not unsafe
unsafe trait MyUnsafeTrait {}
impl MyUnsafeTrait for .. {}
//~^ ERROR the trait `MyUnsafeTrait` requires an `unsafe impl` declaration
fn main() {}