extern "C" {

type Opaque;

struct Newtype(Opaque);

struct S {

i: i32,

j: i32,

a: Newtype,

fn main() {

let buf = [0i32; 4];

let x: &Newtype = unsafe { &*(&buf as *const _ as *const Newtype) };

// Projecting to the newtype works, because it is always at offset 0.

let _field = &x.0;

let x: &S = unsafe { &*(&buf as *const _ as *const S) };

// Accessing sized fields is perfectly fine, even at non-zero offsets.

let _field = &x.i;

let _field = &x.j;

// This needs to compute the field offset, but we don't know the type's alignment,

// so this panics.

let _field = &x.a; //~ERROR: does not have a known offset

error: unsupported operation: `extern type` does not have a known offset

--> $DIR/extern-type-field-offset.rs:LL:CC

|

LL | let _field = &x.a;

| ^^^^ `extern type` does not have a known offset

|

= help: this is likely not a bug in the program; it indicates that the program performed an operation that the interpreter does not support

= note: BACKTRACE:

= note: inside `main` at $DIR/extern-type-field-offset.rs:LL:CC

note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace

error: aborting due to 1 previous error