1 files changed, 62 insertions, 0 deletions
diff --git a/tests/ui/cast/cast-rfc0401-vtable-kinds.rs b/tests/ui/cast/cast-rfc0401-vtable-kinds.rs
new file mode 100644
index 000000000..249481467
--- /dev/null
+++ b/tests/ui/cast/cast-rfc0401-vtable-kinds.rs
@@ -0,0 +1,62 @@
+// 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]);
+    }
+}