src/test/compile-fail/issue-12028.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
  11 // Test an example where we fail to infer the type parameter H. This
  12 // is because there is really nothing constraining it. At one time, we
  13 // would infer based on the where clauses in scope, but that no longer
  14 // works.
  15
  16 trait Hash<H> {
  17     fn hash2(&self, hasher: &H) -> u64;
  18 }
  19
  20 trait Stream {
  21     fn input(&mut self, bytes: &[u8]);
  22     fn result(&self) -> u64;
  23 }
  24
  25 trait StreamHasher {
  26     type S : Stream;
  27     fn stream(&self) -> Self::S;
  28 }
  29
  30 //////////////////////////////////////////////////////////////////////////////
  31
  32 trait StreamHash<H: StreamHasher>: Hash<H> {
  33     fn input_stream(&self, stream: &mut H::S);
  34 }
  35
  36 impl<H: StreamHasher> Hash<H> for u8 {
  37     fn hash2(&self, hasher: &H) -> u64 {
  38         let mut stream = hasher.stream();
  39         self.input_stream(&mut stream); //~ ERROR type annotations required
  40         Stream::result(&stream)
  41     }
  42 }
  43
  44 impl<H: StreamHasher> StreamHash<H> for u8 {
  45     fn input_stream(&self, stream: &mut H::S) {
  46         Stream::input(stream, &[*self]);
  47     }
  48 }
  49
  50 fn main() {}