Changed behavior how to cast and getstring enums with vs2012 in C++/CLI

Question

As the support of C++/CLI was really bad in 2010 (no wizard for c++/cli!), one of my project is still VS2005 C++/CLI. Now is the time to migrate this last project. Unfortunately it comes with errors during compile time. Two of them I do not understand, because they worked perfectly before, try to compile this small snippet on VS2012:

        enum class EMyEnum
        {
            Unknown,
            NotBetter,
        };

        Array ^lEnums=Enum::GetValues(EMyEnum::typeid);
        Object ^test=lEnums->GetValue(0);
        EMyEnum t=(EMyEnum)test;  // VS2012 ERROR -> Cannot cast
        String ^thetext=t.ToString(); // VS2012 ERROR -> Left of ToString() needs object

Needless to say that in VS2005 it not only compile without error or warning, it also works as expected.

Answer 1

Yes, this is a problem in VS2012 and up. This is caused by the C++11 language standard adopting the enum class syntax. The C++/CLI compiler can now no longer distinguish a managed enum type from an unmanaged one. The cast from Object^ is only valid for a managed enum.

The workaround is silly but effective, you should explicitly specify the accessibility of the enum class. Something that's not legal in C++11 but valid in C++/CLI. Fix:

    private enum class EMyEnum      // Note: added private
    {
        Unknown,
        NotBetter,
    };

Or use public.