| //@ 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]" |
| |
| use std::mem; |
| |
| // If this is `None`, the metadata becomes padding. |
| type T = Option<&'static str>; |
| |
| fn main() { |
| unsafe { |
| let mut p: mem::MaybeUninit<T> = mem::MaybeUninit::zeroed(); |
| // The copy when `T` is returned from `transmute` should destroy padding |
| // (even when we use `write_unaligned`, which under the hood uses an untyped copy). |
| p.as_mut_ptr().write_unaligned(mem::transmute((0usize, 0usize))); |
| // Null epresents `None`. |
| assert!(matches!(*p.as_ptr(), None)); |
| |
| // The second part, with the length, becomes padding. |
| let c = &p as *const _ as *const u8; |
| // Read a padding byte. |
| let _val = *c.add(mem::size_of::<*const u8>()); |
| //~^ERROR: uninitialized |
| } |
| } |
