what's more fundamentally missing is ability to use ref on variables. DIP39 should be able to be adapted to that case.

void main(){

int[1000] x1_;

int[1000] x2_;

// do some initialization on x1_,x2_

const(typeof(x)) x1=x1_; //wishful thinking

const(typeof(x)) x2=x2_; //ditto

assert(&x1 is &x1_); // no copy

}