What is aliasing

1

Explain with examples

2

When two pointers or references point to the same location in memory (or to overlapping locations), we say that they alias each other.

For example:

let x = 5;
let a = &x;
let b = &x;
dbg!(a, b); // a and b point to the same value
3 Likes
3

Rust pays attention to aliasing, because it causes subtle odd behaviors:

fn foo(a: &mut i32, b: &i32) {
   if b == 1 {
     *a = 2; 
      // Can a write to a have changed b too?
      // Rust says no, but in languages with mutable aliasing it could be yes
      assert_eq!(b, 1); 
   }
}

let mut x = 1;
// makes both arguments of `foo` share the same value
foo(&mut x, &x); // not allowed in Rust, but allowed in C/C++
5 Likes
4

This topic was automatically closed 90 days after the last reply. We invite you to open a new topic if you have further questions or comments.