Question

enum MyEnum
{
    A,
    B,
}

MyEnum Foo(int i)
{
    MyEnum mx;
    switch(i)
    {
    case 1:
        {
            mx = A;
        }break;
    case 2:
        {
            mx = B;
        }break;
    default:
        {
            throw std::exception("ERROR");
        }
    }
}

int Main()
{
    MyEnum myEnum = Foo(1);
    return 0;
}

Without ‘return’ in Foo( ), This code can be compiled and run in VS2010. Is it compiler bug?

VS2010 screenshot to confirm that it can be run

Answer 1

It is not a compiler bug. A missing return doesn’t require a diagnostics from the compiler (but the compiler might emit one), and it leads to undefined behavior – anything can happen.