Macro const_zero::const_zero

macro_rules! const_zero {
    ($type_:ty) => { ... };
}

A marco that acts similarly to core::mem::zeroed(), only is const

Example usage:

use const_zero::const_zero;
struct OpaqueStruct {
    nothing: core::ffi::c_void,
};
static mut zeroed_opaque: OpaqueStruct = unsafe {const_zero!(OpaqueStruct)};

Ideally const_zero would be a generic function, but const generics need more development first (const_fn_transmute, const_generics, const_evaluatable_checked)

Safety

Similar to core::mem::zeroed(), except this zeroes padding bits. Zeroed padding usually isn’t relevant to safety, but might be if a C union is used. To repeat core::mem::zeroed()’s safety, an all zero byte pattern might not be a valid value for a type; for example, references &T, &mut T.

const_zero does not work on unsized types

use const_zero::const_zero;
// error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
const BYTES: [u8] = unsafe{const_zero!([u8])};

reference types trigger a (denied by default) lint and cause immediate undefined behavior if the lint is ignored

use const_zero::const_zero;
// error: any use of this value will cause an error
// note: `#[deny(const_err)]` on by default
const STR: &str = unsafe{const_zero!(&'static str)};

Differences with core::mem::zeroed

const_zero zeroes padding bits, while core::mem::zeroed doesn’t