src/test/compile-fail/coherence-impl-trait-for-trait.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Test that we give suitable error messages when the user attempts to
  12 // impl a trait `Trait` for its own object type.
  13
  14 trait Foo { fn dummy(&self) { } }
  15 trait Bar: Foo { }
  16 trait Baz: Bar { }
  17
  18 // Subtraits of Baz are not legal:
  19 impl Foo for Baz { }   //~ ERROR E0371
  20 impl Bar for Baz { }   //~ ERROR E0371
  21 impl Baz for Baz { }   //~ ERROR E0371
  22
  23 // But other random traits are:
  24 trait Other { }
  25 impl Other for Baz { } // OK, Bar not a subtrait of Baz
  26
  27 // If the trait is not object-safe, we give a more tailored message
  28 // because we're such schnuckels:
  29 trait NotObjectSafe { fn eq(&self, other: Self); }
  30 impl NotObjectSafe for NotObjectSafe { } //~ ERROR E0372
  31
  32 fn main() { }