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// 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 Foo<T> {
fn foo(&self, _: T) -> u32 { 42 }
}
trait Bar {
fn bar(&self) { println!("Bar!"); }
}
impl<T> Foo<T> for () {}
impl Foo<u32> for u32 { fn foo(&self, _: u32) -> u32 { self+43 } }
impl Bar for () {}
unsafe fn round_trip_and_call<'a>(t: *const (dyn Foo<u32>+'a)) -> u32 {
let foo_e : *const dyn Foo<u16> = t as *const _;
let r_1 = foo_e as *mut dyn Foo<u32>;
(&*r_1).foo(0)
}
#[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 x = 4u32;
let y : &dyn Foo<u32> = &x;
let fl = unsafe { round_trip_and_call(y as *const dyn Foo<u32>) };
assert_eq!(fl, (43+4));
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]);
}
}
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