mirror of https://github.com/rust-lang/rust
94 lines
1.9 KiB
Rust
94 lines
1.9 KiB
Rust
//@ run-pass
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// Test structs with always-unsized fields.
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#![allow(warnings)]
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#![feature(unsize, ptr_metadata)]
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use std::mem;
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use std::ptr;
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use std::slice;
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struct Foo<T> {
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f: [T],
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}
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struct Bar {
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f1: usize,
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f2: [usize],
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}
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struct Baz {
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f1: usize,
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f2: str,
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}
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trait Tr {
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fn foo(&self) -> usize;
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}
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struct St {
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f: usize,
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}
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impl Tr for St {
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fn foo(&self) -> usize {
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self.f
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}
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}
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struct Qux<'a> {
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f: Tr + 'a,
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}
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pub fn main() {
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let _: &Foo<f64>;
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let _: &Bar;
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let _: &Baz;
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let _: Box<Foo<i32>>;
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let _: Box<Bar>;
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let _: Box<Baz>;
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let _ = mem::size_of::<Box<Foo<u8>>>();
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let _ = mem::size_of::<Box<Bar>>();
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let _ = mem::size_of::<Box<Baz>>();
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unsafe {
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struct Foo_<T> {
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f: [T; 3],
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}
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let data: Box<Foo_<i32>> = Box::new(Foo_ { f: [1, 2, 3] });
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let x: &Foo<i32> = mem::transmute(ptr::slice_from_raw_parts(&*data, 3));
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assert_eq!(x.f.len(), 3);
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assert_eq!(x.f[0], 1);
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struct Baz_ {
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f1: usize,
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f2: [u8; 5],
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}
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let data: Box<_> =
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Box::new(Baz_ { f1: 42, f2: ['a' as u8, 'b' as u8, 'c' as u8, 'd' as u8, 'e' as u8] });
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let x: &Baz = mem::transmute(ptr::slice_from_raw_parts(&*data, 5));
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assert_eq!(x.f1, 42);
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let chs: Vec<char> = x.f2.chars().collect();
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assert_eq!(chs.len(), 5);
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assert_eq!(chs[0], 'a');
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assert_eq!(chs[1], 'b');
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assert_eq!(chs[2], 'c');
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assert_eq!(chs[3], 'd');
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assert_eq!(chs[4], 'e');
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struct Qux_ {
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f: St,
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}
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let obj: Box<St> = Box::new(St { f: 42 });
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let obj: &Tr = &*obj;
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let data: Box<_> = Box::new(Qux_ { f: St { f: 234 } });
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let x: &Qux = &*ptr::from_raw_parts::<Qux>(&*data as *const _, ptr::metadata(obj));
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assert_eq!(x.f.foo(), 234);
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}
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}
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