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#![feature(rustc_attrs)]
#![allow(unused,dead_code)]
fn tuple_struct() {
#[rustc_layout_scalar_valid_range_start(1)]
struct NonZero<T>(T);
let mut foo = unsafe { NonZero((1,)) };
let a = &mut foo.0.0;
//~^ ERROR: mutation of layout constrained field is unsafe
}
fn slice() {
#[rustc_layout_scalar_valid_range_start(1)]
struct NonZero<'a, T>(&'a mut [T]);
let mut nums = [1, 2, 3, 4];
let mut foo = unsafe { NonZero(&mut nums[..]) };
let a = &mut foo.0[2];
// ^ not unsafe because there is an implicit dereference here
}
fn array() {
#[rustc_layout_scalar_valid_range_start(1)]
struct NonZero<T>([T; 4]);
let nums = [1, 2, 3, 4];
let mut foo = unsafe { NonZero(nums) };
let a = &mut foo.0[2];
//~^ ERROR: mutation of layout constrained field is unsafe
}
fn block() {
#[rustc_layout_scalar_valid_range_start(1)]
struct NonZero<T>(T);
let foo = unsafe { NonZero((1,)) };
&mut { foo.0 }.0;
// ^ not unsafe because the result of the block expression is a new place
}
fn mtch() {
#[rustc_layout_scalar_valid_range_start(1)]
struct NonZero<T>(T);
let mut foo = unsafe { NonZero((1,)) };
match &mut foo {
NonZero((a,)) => *a = 0,
//~^ ERROR: mutation of layout constrained field is unsafe
}
}
fn main() {}
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