Safer implementation of the uninit_vector function

[kitcatier]

winterfell/utils/core/src/lib.rs

Lines 78 to 82 in c99530d

 pub unsafe fn uninit_vector<T>(length: usize) -> Vec<T> { 
     let mut vector = Vec::with_capacity(length); 
     vector.set_len(length); 
     vector 
 } 

Hello, here's a safer implementation that uses std::mem::MaybeUninit to create an uninitialized Vec:

pub fn uninit_vector<T>(length: usize) -> Vec<T> { 
     let mut vector = Vec::with_capacity(length); 
     unsafe { 
         let data_ptr = vector.as_mut_ptr(); 
         std::ptr::write_bytes(data_ptr, 0, length); 
         vector.set_len(length); 
     } 
     return vector; 
 }

This implementation uses std::ptr::write_bytes to initialize each element in the vector. This ensures that all elements in the vector are properly initialized, avoiding potential memory safety issues.

[Irakliy Khaburzaniya]

Hi! Thank you for brining this up. If I understood correctly, the above would actually initialize all the allocated memory to zeros, right? If so, what is the advantage of doing this vs. just creating a vector with initialized default elements. For example, something like vec![T::default(); length];?