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rustunsafe

Why does this unsafe block return a unit type?

I haven't quite understood how unsafe and assignments work together. The following code gives me some error:

fn num() -> u64 {
    1;
}

fn test() -> u64 {
    let x = unsafe {
        num();
    };
    return x;
}

The error is:

src/main.rs:37:9: 37:10 note: expected type `u64`
src/main.rs:37:9: 37:10 note:    found type `()`

My real example is similar to this one.

Solution

  • Semicolons.

    fn num() -> u64 {
    1
}

fn test() -> u64 {
    let x = unsafe {
        num()
    };
    return x;
}

    See also this answer about semicolons.