Question

I’m playing around with the Visual Studio 11 Beta at the moment. I’m using a strongly typed enum to describe some flags

enum class A : uint32_t
{
    VAL1 = 1 << 0,
    VAL2 = 1 << 1,
};
uint32_t v = A::VAL1 | A::VAL2;    // Fails

When I attempt to combine them as above I get the following error

error C2676: binary '|' : 'A' does not define this operator or a conversion to a type acceptable to the predefined operator

Is this a bug with the compiler or is what I’m attempting invalid according to the c++11 standard?

My assumption had been that the previous enum declaration would be equivalent to writing

struct A
{
    enum : uint32_t
    {
        VAL1 = 1 << 0,
        VAL2 = 1 << 1,
    };
};
uint32_t v = A::VAL1 | A::VAL2;    // Succeeds, v = 3

Answer 1

Strongly typed enums are not implicitly convertible to integer types even if its underlying type is uint32_t, you need to explicitly cast to uint32_t to achieve what you are doing.