src/test/compile-fail/on-unimplemented.rs

   1 // Copyright 2014 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 // ignore-tidy-linelength
  11
  12 #![feature(on_unimplemented)]
  13
  14 #[rustc_on_unimplemented = "test error `{Self}` with `{Bar}` `{Baz}` `{Quux}`"]
  15 trait Foo<Bar, Baz, Quux>
  16 {}
  17
  18 fn foobar<U: Clone, T: Foo<u8, U, u32>>() -> T {
  19
  20 }
  21
  22 #[rustc_on_unimplemented="a collection of type `{Self}` cannot be built from an iterator over elements of type `{A}`"]
  23 trait MyFromIterator<A> {
  24     /// Build a container with elements from an external iterator.
  25     fn my_from_iter<T: Iterator<Item=A>>(iterator: T) -> Self;
  26 }
  27
  28 fn collect<A, I: Iterator<Item=A>, B: MyFromIterator<A>>(it: I) -> B {
  29     MyFromIterator::my_from_iter(it)
  30 }
  31
  32 pub fn main() {
  33     let x = vec!(1u8, 2, 3, 4);
  34     let y: Option<Vec<u8>> = collect(x.iter()); // this should give approximately the same error for x.iter().collect()
  35     //~^ ERROR
  36     //~^^ NOTE a collection of type `std::option::Option<std::vec::Vec<u8>>` cannot be built from an iterator over elements of type `&u8`
  37     //~^^^ NOTE required by `collect`
  38     let x: String = foobar(); //~ ERROR
  39     //~^ NOTE test error `std::string::String` with `u8` `_` `u32`
  40     //~^^ NOTE required by `foobar`
  41 }