A Rustacean with a wry sense of humor suggested that now would be a good time to pitch the Underhanded Rust Contest https://underhanded.rs/blog/2016/12/15/underhanded-rust.en-U...

Glad that the soundness bug was caught so quickly, and that the new version has been put out so quickly. Thanks Rust team!

I'm new to rust. Can someone explain what is the issue with following code?

    pub fn as_mut_slice(&self) -> &mut [T] {
        unsafe {
            slice::from_raw_parts_mut(self.ptr as *mut T, self.len())
        }
    }

The post goes on to explain it, was there something specific about that that's confusing?

My confusion was why the compiler didn't catch this, it is suppose to spot this sort of thing right?

Now that I think about it, maybe it has to do with `unsafe` block so the compiler doesn't check it.

My next question would be why does it need `unsafe`?

Ah yes, it's because of the `unsafe`.

> why does it need `unsafe`?

slice::from_raw_parts_mut is an unsafe function because it lets you conjure a slice from thin air; there's no checking of it at all.

This function is used because it's the most straightforward way of accomplishing the task.

Quick and responsible, good job.