Macro munge 

macro_rules! munge {
    ($($t:tt)*) => { ... };
}

Destructures a type using a pattern.

To prevent unsound union destructurings, this macro emits field accesses which fail to compile in safe Rust. However, if munge! is used inside of an unsafe block, these accesses will compile without emitting an error. This matches the behavior of regular destructuring, but may be surprising in some situations.

Example

pub struct Example {
    a: u32,
    b: (char, f32),
}

let mut mu = MaybeUninit::<Example>::uninit();

munge!(let Example { a, b: (c, mut f) } = &mut mu);
assert_eq!(a.write(10), &10);
assert_eq!(c.write('x'), &'x');
assert_eq!(f.write(3.14), &3.14);
// Note that `mut` bindings can be reassigned like you'd expect:
let mut new_f = MaybeUninit::uninit();
f = &mut new_f;

// SAFETY: `mu` is completely initialized.
let init = unsafe { mu.assume_init() };
assert_eq!(init.a, 10);
assert_eq!(init.b.0, 'x');
assert_eq!(init.b.1, 3.14);