src/test/run-pass/mir/mir_coercions.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 // run-pass
  12 #![feature(coerce_unsized, unsize)]
  13
  14 use std::ops::CoerceUnsized;
  15 use std::marker::Unsize;
  16
  17 fn identity_coercion(x: &(Fn(u32)->u32 + Send)) -> &Fn(u32)->u32 {
  18     x
  19 }
  20 fn fn_coercions(f: &fn(u32) -> u32) ->
  21     (unsafe fn(u32) -> u32,
  22      &(Fn(u32) -> u32+Send))
  23 {
  24     (*f, f)
  25 }
  26
  27 fn simple_array_coercion(x: &[u8; 3]) -> &[u8] { x }
  28
  29 fn square(a: u32) -> u32 { a * a }
  30
  31 #[derive(PartialEq,Eq)]
  32 struct PtrWrapper<'a, T: 'a+?Sized>(u32, u32, (), &'a T);
  33 impl<'a, T: ?Sized+Unsize<U>, U: ?Sized>
  34     CoerceUnsized<PtrWrapper<'a, U>> for PtrWrapper<'a, T> {}
  35
  36 struct TrivPtrWrapper<'a, T: 'a+?Sized>(&'a T);
  37 impl<'a, T: ?Sized+Unsize<U>, U: ?Sized>
  38     CoerceUnsized<TrivPtrWrapper<'a, U>> for TrivPtrWrapper<'a, T> {}
  39
  40 fn coerce_ptr_wrapper(p: PtrWrapper<[u8; 3]>) -> PtrWrapper<[u8]> {
  41     p
  42 }
  43
  44 fn coerce_triv_ptr_wrapper(p: TrivPtrWrapper<[u8; 3]>) -> TrivPtrWrapper<[u8]> {
  45     p
  46 }
  47
  48 fn coerce_fat_ptr_wrapper(p: PtrWrapper<Fn(u32) -> u32+Send>)
  49                           -> PtrWrapper<Fn(u32) -> u32> {
  50     p
  51 }
  52
  53 fn coerce_ptr_wrapper_poly<'a, T, Trait: ?Sized>(p: PtrWrapper<'a, T>)
  54                                                  -> PtrWrapper<'a, Trait>
  55     where PtrWrapper<'a, T>: CoerceUnsized<PtrWrapper<'a, Trait>>
  56 {
  57     p
  58 }
  59
  60 fn main() {
  61     let a = [0,1,2];
  62     let square_local : fn(u32) -> u32 = square;
  63     let (f,g) = fn_coercions(&square_local);
  64     assert_eq!(f as usize, square as usize);
  65     assert_eq!(g(4), 16);
  66     assert_eq!(identity_coercion(g)(5), 25);
  67
  68     assert_eq!(simple_array_coercion(&a), &a);
  69     let w = coerce_ptr_wrapper(PtrWrapper(2,3,(),&a));
  70     assert!(w == PtrWrapper(2,3,(),&a) as PtrWrapper<[u8]>);
  71
  72     let w = coerce_triv_ptr_wrapper(TrivPtrWrapper(&a));
  73     assert_eq!(&w.0, &a);
  74
  75     let z = coerce_fat_ptr_wrapper(PtrWrapper(2,3,(),&square_local));
  76     assert_eq!((z.3)(6), 36);
  77
  78     let z: PtrWrapper<Fn(u32) -> u32> =
  79         coerce_ptr_wrapper_poly(PtrWrapper(2,3,(),&square_local));
  80     assert_eq!((z.3)(6), 36);
  81 }