2.31

[iMinder]

r1 = v2, this is illegal, r1 is normal int & , can not bind to cont int

[pezy]

@iMinder r1 = v2; It is assigned value to v1(which is bind to r1), rather than bind again. You can try it by compiler.

[Mooophy]

Agree @pezy
@iMinder You can look at it like this: After defining r1, r1 becomes another name for variable v1, a.k.a aliasing.
So:

r1 = v2;

is equivalent to :

v1 = v2;

Like @pezy said, this statement has nothing to do with binding.