tests/ui/unsized/unsized3-rpass.rs

   1 // run-pass
   2 // Test structs with always-unsized fields.
   3
   4 #![allow(warnings)]
   5 #![feature(unsize, ptr_metadata)]
   6
   7 use std::mem;
   8 use std::ptr;
   9 use std::slice;
  10
  11 struct Foo<T> {
  12     f: [T],
  13 }
  14
  15 struct Bar {
  16     f1: usize,
  17     f2: [usize],
  18 }
  19
  20 struct Baz {
  21     f1: usize,
  22     f2: str,
  23 }
  24
  25 trait Tr {
  26     fn foo(&self) -> usize;
  27 }
  28
  29 struct St {
  30     f: usize,
  31 }
  32
  33 impl Tr for St {
  34     fn foo(&self) -> usize {
  35         self.f
  36     }
  37 }
  38
  39 struct Qux<'a> {
  40     f: Tr + 'a,
  41 }
  42
  43 pub fn main() {
  44     let _: &Foo<f64>;
  45     let _: &Bar;
  46     let _: &Baz;
  47
  48     let _: Box<Foo<i32>>;
  49     let _: Box<Bar>;
  50     let _: Box<Baz>;
  51
  52     let _ = mem::size_of::<Box<Foo<u8>>>();
  53     let _ = mem::size_of::<Box<Bar>>();
  54     let _ = mem::size_of::<Box<Baz>>();
  55
  56     unsafe {
  57         struct Foo_<T> {
  58             f: [T; 3],
  59         }
  60
  61         let data: Box<Foo_<i32>> = Box::new(Foo_ { f: [1, 2, 3] });
  62         let x: &Foo<i32> = mem::transmute(ptr::slice_from_raw_parts(&*data, 3));
  63         assert_eq!(x.f.len(), 3);
  64         assert_eq!(x.f[0], 1);
  65
  66         struct Baz_ {
  67             f1: usize,
  68             f2: [u8; 5],
  69         }
  70
  71         let data: Box<_> =
  72             Box::new(Baz_ { f1: 42, f2: ['a' as u8, 'b' as u8, 'c' as u8, 'd' as u8, 'e' as u8] });
  73         let x: &Baz = mem::transmute(ptr::slice_from_raw_parts(&*data, 5));
  74         assert_eq!(x.f1, 42);
  75         let chs: Vec<char> = x.f2.chars().collect();
  76         assert_eq!(chs.len(), 5);
  77         assert_eq!(chs[0], 'a');
  78         assert_eq!(chs[1], 'b');
  79         assert_eq!(chs[2], 'c');
  80         assert_eq!(chs[3], 'd');
  81         assert_eq!(chs[4], 'e');
  82
  83         struct Qux_ {
  84             f: St,
  85         }
  86
  87         let obj: Box<St> = Box::new(St { f: 42 });
  88         let obj: &Tr = &*obj;
  89         let data: Box<_> = Box::new(Qux_ { f: St { f: 234 } });
  90         let x: &Qux = &*ptr::from_raw_parts::<Qux>((&*data as *const _).cast(), ptr::metadata(obj));
  91         assert_eq!(x.f.foo(), 234);
  92     }
  93 }