#![feature(rustc_attrs)] use std::cell::Cell; #[rustc_layout_scalar_valid_range_start(1)] #[repr(transparent)] pub(crate) struct NonZero(pub(crate) T); fn main() {} const fn foo() -> NonZero> { let mut x = unsafe { NonZero(Cell::new(1)) }; let y = &x.0; //~^ ERROR borrow of layout constrained field with interior mutability unsafe { NonZero(Cell::new(1)) } } const fn bar() -> NonZero> { let mut x = unsafe { NonZero(Cell::new(1)) }; let y = unsafe { &x.0 }; unsafe { NonZero(Cell::new(1)) } }