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//@ run-pass
#[repr(packed)]
struct Packed<T: Copy>(#[allow(dead_code)] T);
impl<T: Copy> Copy for Packed<T> {}
impl<T: Copy> Clone for Packed<T> {
fn clone(&self) -> Self { *self }
}
fn sanity_check_size<T: Copy>(one: T) {
let two = [one, one];
let stride = (&two[1] as *const _ as usize) - (&two[0] as *const _ as usize);
let (size, align) = (std::mem::size_of::<T>(), std::mem::align_of::<T>());
assert_eq!(stride, size);
assert_eq!(size % align, 0);
}
fn main() {
// This can fail if rustc and LLVM disagree on the size of a type.
// In this case, `Option<Packed<(&(), u32)>>` was erroneously not
// marked as packed despite needing alignment `1` and containing
// its `&()` discriminant, which has alignment larger than `1`.
sanity_check_size((Some(Packed((&(), 0))), true));
// In #46769, `Option<(Packed<&()>, bool)>` was found to have
// pointer alignment, without actually being aligned in size.
// e.g., on 64-bit platforms, it had alignment `8` but size `9`.
type PackedRefAndBool<'a> = (Packed<&'a ()>, bool);
sanity_check_size::<Option<PackedRefAndBool>>(Some((Packed(&()), true)));
// Make sure we don't pay for the enum optimization in size,
// e.g., we shouldn't need extra padding after the packed data.
assert_eq!(std::mem::align_of::<Option<PackedRefAndBool>>(), 1);
assert_eq!(std::mem::size_of::<Option<PackedRefAndBool>>(),
std::mem::size_of::<PackedRefAndBool>());
}
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