Announcing Rust 1.15.1

Re:Announcing Rust 1.15.1 by saintfiends on Saturday February 11, 2017 @11:22AM (#13623225)

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())
        }
    }

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Re:Announcing Rust 1.15.1 by steveklabnik on Saturday February 11, 2017 @02:32PM (#13624280)

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

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Re:Announcing Rust 1.15.1 by saintfiends on Sunday February 12, 2017 @12:35AM (#13626951)

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`?

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Re:Announcing Rust 1.15.1 by steveklabnik on Sunday February 12, 2017 @01:07AM (#13627044)

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.

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