Describe the bug

The StringView::as_utf8_str function in its current implementation is unsound and may lead to undefined behavior (UB) under certain conditions. The function uses an unchecked raw pointer (ptr) and skips UTF-8 validation via from_utf8_unchecked. These unsafe operations can easily result in UB when the ptr field points to invalid memory or when the data at ptr is not valid UTF-8.

Steps to reproduce

pub struct StringView {
    pub len: u32,
    //pub prefix: [u8; STRING_VIEW_PREFIX_LEN],
    pub ptr: usize,
}

impl StringView {
    pub fn as_utf8_str(&self) -> &str {
        unsafe {
            let slice = std::slice::from_raw_parts(self.ptr as *const u8, self.len as usize);
            std::str::from_utf8_unchecked(slice)
        }
    }
}

fn main() {
    let invalid_ptr = 0xdeadbeef_usize; 

    let string_view = StringView {
        len: 10,
        ptr: invalid_ptr,
    };

    let result = string_view.as_utf8_str();
    println!("Result: {}", result);
}

Expected behavior

The function should validate the pointer and ensure it points to valid memory. Additionally, it should verify that the data is valid UTF-8 before returning a &str.

Additional context

Note that I'm currently only emulating the implementation of this function, and since it doesn't appear to be published to crates.io, I commented out a field to facilitate triggering the UB. But considering that this data_type mod is not a pub mod, I am only reporting this issue for possible security risks, if in fact it is safe here, please don't mind.