src/test/run-pass/regions-no-variance-from-fn-generics.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 // Issue #12856: a lifetime formal binding introduced by a generic fn
  12 // should not upset the variance inference for actual occurrences of
  13 // that lifetime in type expressions.
  14
  15 // pretty-expanded FIXME #23616
  16
  17 pub trait HasLife<'a> {
  18     fn dummy(&'a self) { } // just to induce a variance on 'a
  19 }
  20
  21 trait UseLife01 {
  22     fn refs<'a, H: HasLife<'a>>(&'a self) -> H;
  23 }
  24
  25 trait UseLife02 {
  26     fn refs<'a, T, H: HasType<&'a T>>(&'a self) -> H;
  27 }
  28
  29
  30 pub trait HasType<T>
  31 {
  32     fn dummy(&self, t: T) -> T { panic!() }
  33 }
  34
  35
  36 trait UseLife03<T> {
  37     fn refs<'a, H: HasType<&'a T>>(&'a self) -> H;
  38 }
  39
  40
  41 // (The functions below were not actually a problem observed during
  42 // fixing of #12856; they just seem like natural tests to put in to
  43 // cover a couple more points in the testing space)
  44
  45 pub fn top_refs_1<'a, H: HasLife<'a>>(_s: &'a ()) -> H {
  46     unimplemented!()
  47 }
  48
  49 pub fn top_refs_2<'a, T, H: HasType<&'a T>>(_s: &'a ()) -> H {
  50     unimplemented!()
  51 }
  52
  53 pub fn main() {}