src/test/run-pass/unit-fallback.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 diverging types default to () (with feature(never_type) disabled).
  12
  13 trait Balls: Sized {
  14     fn smeg() -> Result<Self, ()>;
  15 }
  16
  17 impl Balls for () {
  18     fn smeg() -> Result<(), ()> { Ok(()) }
  19 }
  20
  21 struct Flah;
  22
  23 impl Flah {
  24     fn flah<T: Balls>(&self) -> Result<T, ()> {
  25         T::smeg()
  26     }
  27 }
  28
  29 fn doit() -> Result<(), ()> {
  30     // The type of _ is unconstrained here and should default to ()
  31     let _ = try!(Flah.flah());
  32     Ok(())
  33 }
  34
  35 fn main() {
  36     let _ = doit();
  37 }
  38