`Register` trait is unsound

[WaffleLapkin]

Register trait allows reading and writing any pointer in safe code which is unsound.

Example:

use ruduino::Register;

struct Unsound;

impl Register for Unsound {
    type T = u8;

    const ADDRESS: *mut Self::T = core::ptr::null_mut();

    // default implementations of `write`, `read`, `set_musk_raw`, `toggle_raw`, 
    // `is_mask_set_raw` and `is_clear_raw` dereference `Self::ADDRESS`
    // (other methods also depend on them)
}

fn main() {
    println!("{}", Unsound::read());
}

(for me in debug it produces Process finished with exit code 139 (interrupted by signal 11: SIGSEGV) and in the release mode it prints 0)

Possible solutions:

• make Register trait unsafe
• do not provide unsound default impls

[shepmaster]

Yeah that should definitely be an unsafe trait. Maybe also sealed as no one should be able to implement it out of the library.