Just for you, a slightly adapted version:
----
import std.stdio;
struct A {
public int id = 0;
this(int id) {
this.id = id;
}
ref A byRef() {
return this;
}
}
void foo(ref const A a) {
writeln(a.id);
}
void main() {
foo(A(42).byRef());
}
----