| #![feature(rustc_attrs)] |
| |
| use std::cell::Cell; |
| |
| #[rustc_layout_scalar_valid_range_start(1)] |
| #[repr(transparent)] |
| pub(crate) struct NonZero<T>(pub(crate) T); |
| fn main() { |
| let mut x = unsafe { NonZero(Cell::new(1)) }; |
| match x { |
| NonZero(ref x) => { x } |
| //~^ ERROR borrow of layout constrained field with interior mutability |
| }; |
| |
| let mut y = unsafe { NonZero(42) }; |
| match y { NonZero(ref y) => { y } }; // OK, type of `y` is freeze |
| match y { NonZero(ref mut y) => { y } }; |
| //~^ ERROR mutation of layout constrained field |
| } |