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// stderr-per-bitwidth
// compile-flags: -Zunleash-the-miri-inside-of-you
use std::cell::UnsafeCell;
// this test ensures that our mutability story is sound
struct Meh {
x: &'static UnsafeCell<i32>,
}
unsafe impl Sync for Meh {}
// the following will never be ok! no interior mut behind consts, because
// all allocs interned here will be marked immutable.
const MUH: Meh = Meh { //~ ERROR: it is undefined behavior to use this value
x: &UnsafeCell::new(42),
};
struct Synced {
x: UnsafeCell<i32>,
}
unsafe impl Sync for Synced {}
// Make sure we also catch this behind a type-erased `dyn Trait` reference.
const SNEAKY: &dyn Sync = &Synced { x: UnsafeCell::new(42) };
//~^ ERROR: it is undefined behavior to use this value
// Make sure we also catch mutable references.
const BLUNT: &mut i32 = &mut 42;
//~^ ERROR: it is undefined behavior to use this value
fn main() {
unsafe {
*MUH.x.get() = 99;
}
}
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