Is it safe to reinterpret_cast an enum class variable to a reference of the underlying type?

Question

I\'ve seen reinterpret_cast used to apply incrementation to enum classes, and I\'d like to know if this usage is acceptable in standard C++.

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Answer 1

It is safe as long as it casts to the exact underlying type of the enum.

If the underlying type of the enum class changes that ++reinterpret_cast(foo) breaks silently.

A safer version:

foo = static_cast(static_cast::type>(foo) + 1);

Or,

++reinterpret_cast::type&>(foo);