10.2.3 Amplification

[hahn]

Hi,

I find the amplification of rule 10.2.3 confusing.

In general I wonder what the difference to a simple "no implicit conversion from unscoped enumeration type without underlying type to numeric type" (plus the exception for static_cast in bullet point 3) is?

In particular, as example, for the following code

Code:

enum E {E1, E2};
int f(int);
E operator+(E, E);
int main() {
  E e = E1;
  f(e); // Compliant? (1)
  e = e + e; // Non-compliant (2)
}

I wonder whether (1) should be compliant or not. At least it is not listed in the amplification, but seems like a problematic case anyway.
In turn, should (2) be non-compliant as operands to "arithmetic operator" are explicitly listed in the amplification, while I think this case is absolutely fine.

It would be great to get a clarification on what the rule intends.