How to use transmute safely

Use std::mem::transmute only when you are certain the source and destination types have identical memory layouts and lifetimes, as it bypasses all safety checks. Wrap the operation in an unsafe block and ensure the types are #[repr(C)] or #[repr(transparent)] to guarantee layout compatibility.

use std::mem;

#[repr(C)]
struct Point { x: f64, y: f64 }

fn main() {
    let point = Point { x: 1.0, y: 2.0 };
    // Only safe if Point and [f64; 2] have identical layout
    let arr: [f64; 2] = unsafe { mem::transmute(point) };
}

Transmute is like telling the computer to treat a block of memory as a completely different shape without checking if it fits. It is dangerous because if the shapes don't match exactly, your program will crash or produce garbage data. Only use it when you are 100% sure the underlying data structure is identical, such as converting between a struct and an array of the same size.