What is aliasing

Explain with examples

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

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++

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