| //@ normalize-stderr-test: "(\n)ALLOC \(.*\) \{\n(.*\n)*\}(\n)" -> "${1}ALLOC DUMP${3}" |
| //@ normalize-stderr-test: "\[0x[0-9a-z]..0x[0-9a-z]\]" -> "[0xX..0xY]" |
| |
| #![feature(core_intrinsics)] |
| |
| use std::mem::{self, MaybeUninit}; |
| |
| fn main() { |
| // This constructs a `(usize, bool)` pair: 9 bytes initialized, the rest not. |
| // Ensure that these 9 bytes are indeed initialized, and the rest is indeed not. |
| // This should be the case even if we write into previously initialized storage. |
| let mut x: MaybeUninit<Box<[u8]>> = MaybeUninit::zeroed(); |
| let z = std::intrinsics::add_with_overflow(0usize, 0usize); |
| unsafe { x.as_mut_ptr().cast::<(usize, bool)>().write(z) }; |
| // Now read this bytewise. There should be (`ptr_size + 1`) def bytes followed by |
| // (`ptr_size - 1`) undef bytes (the padding after the bool) in there. |
| let z: *const u8 = &x as *const _ as *const _; |
| let first_undef = mem::size_of::<usize>() as isize + 1; |
| for i in 0..first_undef { |
| let byte = unsafe { *z.offset(i) }; |
| assert_eq!(byte, 0); |
| } |
| let v = unsafe { *z.offset(first_undef) }; |
| //~^ ERROR: uninitialized |
| if v == 0 { |
| println!("it is zero"); |
| } |
| } |
