ex2.31

[hhdidid]

r1 is a int&, while v2 is a const int.
Why it is legel?

r1 = v2; // legal, top-level const in v2 is ignored.

[KshZh]

This is assignment rather than binding.

[mental1104]

Same question, the example in the book says int &r = ci (const int ci = 42), is illegal, which is same as "r1 = v2", so I think "r1 = v2" should be illegal.

[Fanloe]

At first, I thought it's illegal.
Then I wrote a program to verify it:
const int v2 = 0;
int &r1 = v2;
This is illegal;
Then I find that r1 has been bound to v1, so r1 represents v1 which is an int type. The appropriate program is:
int v1 = 0;
const int v2 = 0;
int &r1 = v1;
r1 = v2;
That's right. It's legal as an assignment.