mirror of https://github.com/rust-lang/rust
45 lines
1.1 KiB
Rust
45 lines
1.1 KiB
Rust
//@ run-pass
|
|
// Check that you can cast between different pointers to trait objects
|
|
// whose vtable have the same kind (both lengths, or both trait pointers).
|
|
|
|
#![feature(unsized_tuple_coercion)]
|
|
|
|
trait Bar { //~ WARN trait `Bar` is never used
|
|
fn bar(&self) { println!("Bar!"); }
|
|
}
|
|
|
|
impl Bar for () {}
|
|
|
|
#[repr(C)]
|
|
struct FooS<T:?Sized>(T);
|
|
#[repr(C)]
|
|
struct BarS<T:?Sized>(T);
|
|
|
|
fn foo_to_bar<T:?Sized>(u: *const FooS<T>) -> *const BarS<T> {
|
|
u as *const BarS<T>
|
|
}
|
|
|
|
fn tuple_i32_to_u32<T:?Sized>(u: *const (i32, T)) -> *const (u32, T) {
|
|
u as *const (u32, T)
|
|
}
|
|
|
|
|
|
fn main() {
|
|
let s = FooS([0,1,2]);
|
|
let u: &FooS<[u32]> = &s;
|
|
let u: *const FooS<[u32]> = u;
|
|
let bar_ref : *const BarS<[u32]> = foo_to_bar(u);
|
|
let z : &BarS<[u32]> = unsafe{&*bar_ref};
|
|
assert_eq!(&z.0, &[0,1,2]);
|
|
|
|
// this assumes that tuple reprs for (i32, _) and (u32, _) are
|
|
// the same.
|
|
let s = (0i32, [0, 1, 2]);
|
|
let u: &(i32, [u8]) = &s;
|
|
let u: *const (i32, [u8]) = u;
|
|
let u_u32 : *const (u32, [u8]) = tuple_i32_to_u32(u);
|
|
unsafe {
|
|
assert_eq!(&(*u_u32).1, &[0, 1, 2]);
|
|
}
|
|
}
|