src/test/run-pass/unsized3.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 structs with always-unsized fields.
  12
  13
  14 #![allow(warnings)]
  15 #![feature(box_syntax, unsize, raw)]
  16
  17 use std::mem;
  18 use std::raw;
  19 use std::slice;
  20
  21 struct Foo<T> {
  22     f: [T],
  23 }
  24
  25 struct Bar {
  26     f1: usize,
  27     f2: [usize],
  28 }
  29
  30 struct Baz {
  31     f1: usize,
  32     f2: str,
  33 }
  34
  35 trait Tr {
  36     fn foo(&self) -> usize;
  37 }
  38
  39 struct St {
  40     f: usize
  41 }
  42
  43 impl Tr for St {
  44     fn foo(&self) -> usize {
  45         self.f
  46     }
  47 }
  48
  49 struct Qux<'a> {
  50     f: Tr+'a
  51 }
  52
  53 pub fn main() {
  54     let _: &Foo<f64>;
  55     let _: &Bar;
  56     let _: &Baz;
  57
  58     let _: Box<Foo<i32>>;
  59     let _: Box<Bar>;
  60     let _: Box<Baz>;
  61
  62     let _ = mem::size_of::<Box<Foo<u8>>>();
  63     let _ = mem::size_of::<Box<Bar>>();
  64     let _ = mem::size_of::<Box<Baz>>();
  65
  66     unsafe {
  67         struct Foo_<T> {
  68             f: [T; 3]
  69         }
  70
  71         let data: Box<Foo_<i32>> = box Foo_{f: [1, 2, 3] };
  72         let x: &Foo<i32> = mem::transmute(slice::from_raw_parts(&*data, 3));
  73         assert_eq!(x.f.len(), 3);
  74         assert_eq!(x.f[0], 1);
  75
  76         struct Baz_ {
  77             f1: usize,
  78             f2: [u8; 5],
  79         }
  80
  81         let data: Box<_> = box Baz_ {
  82             f1: 42, f2: ['a' as u8, 'b' as u8, 'c' as u8, 'd' as u8, 'e' as u8] };
  83         let x: &Baz = mem::transmute(slice::from_raw_parts(&*data, 5));
  84         assert_eq!(x.f1, 42);
  85         let chs: Vec<char> = x.f2.chars().collect();
  86         assert_eq!(chs.len(), 5);
  87         assert_eq!(chs[0], 'a');
  88         assert_eq!(chs[1], 'b');
  89         assert_eq!(chs[2], 'c');
  90         assert_eq!(chs[3], 'd');
  91         assert_eq!(chs[4], 'e');
  92
  93         struct Qux_ {
  94             f: St
  95         }
  96
  97         let obj: Box<St> = box St { f: 42 };
  98         let obj: &Tr = &*obj;
  99         let obj: raw::TraitObject = mem::transmute(&*obj);
 100         let data: Box<_> = box Qux_{ f: St { f: 234 } };
 101         let x: &Qux = mem::transmute(raw::TraitObject { vtable: obj.vtable,
 102                                                         data: mem::transmute(&*data) });
 103         assert_eq!(x.f.foo(), 234);
 104     }
 105 }