Rust 阴影内存管理

Question

fn main() {
  let x = 5;
  let x = x + 1;
  let x = x * 2;
  println!("The value of x is: {}", x);
}

When your code calls a function the function's local variables get pushed onto the stack. When the function is over, those values get popped off the stack.

During shadowing what happens to the variable x that we declared first? Do we overwrite the memory location of x or we create a new x at another location in the stack?

Answer 1

Do we overwrite the memory location of x or we create a new x at another location?

Semantically, a new memory location is created and "x" now points to that location. Depending on the optimisations being applied, the compiler could reuse the memory location instead. Or not even allocate a memory location at all, really eg here with optimisations enabled it'll constant fold everything and directly print the constant 12 .