[Question] `unsafe` on the traits `RawLock` and `RawTryLock`

[ICubE-]

In src/lock/api.rs, we have RawLock and RawTryLock traits and they are unsafe.
Why are they unsafe traits? Removing unsafe seems to work fine.
Is it just for indicating api developers that the trait needs more attention when they're implemented?

pub unsafe trait RawLock: Default + Send + Sync {
    type Token;
    fn lock(&self) -> Self::Token;
    unsafe fn unlock(&self, token: Self::Token);
}
pub unsafe trait RawTryLock: RawLock {
    fn try_lock(&self) -> Result<Self::Token, ()>;
}

[kingdoctor123]

Yes you're correct. See related explanation here: https://google.github.io/comprehensive-rust/unsafe-rust/unsafe-traits.html#implementing-unsafe-traits.

[ICubE-]

Thank you for the answer!
So, unsafe trait on RawLock means that "Any struct implementing this trait must guarantee the additional safety requirements to be hold. The developer have to ensure it." And the safety requirement is:

/// # Safety
/// Implementations of this trait must ensure that the lock is actually
/// exclusive: a lock can't be acquired while the lock is already locked.