Is there a way to use a keyword as identifier in an enum?

Question

I have been unable to find if there is a way to use a keyword in a enum definition, like:

enum class EServerAction
{
    create,
    read,
    update,
    delete
};

In C# I can use the @ char to make the compiler look at it as an identifier. Is there a way to do this in C++ (Visual Studio 2015)?

Answer 1

No they cant be used.

From MSDN

Keywords are predefined reserved identifiers that have special meanings. They cannot be used as identifiers in your program.

The rule for identifier says:

An identifier can be used to name objects, references, functions, enumerators, types, class members, namespaces, templates, template specializations, parameter packs, goto labels, and other entities, with the following exceptions:

• the identifiers that are keywords cannot be used for other purposes;
• the identifiers with a double underscore anywhere are reserved;
• the identifiers that begin with an underscore followed by an uppercase letter are reserved;
• the identifiers that begin with an underscore are reserved in the global namespace.

Answer 2

As per 2.12 [lex.key] in the C++14 standard, certain identifiers must never be used as identifiers:

The identifiers shown in Table 4 are reserved for use as keywords (that is, they are unconditionally treated as keywords in phase 7) except in an attribute token (7.6.1) [ Note: The export keyword is unused but is reserved for future use. — end note ]:

Table 4 — Keywords

   alignas continue friend register true
   alignof decltype goto reinterpret_cast try
   asm default if return typedef
   auto delete inline short typeid
   bool do int signed typename
   break double long sizeof union
   case dynamic_cast mutable static unsigned
   catch else namespace static_assert using
   char enum new static_cast virtual
   char16_t explicit noexcept struct void
   char32_t export nullptr switch volatile
   class extern operator template wchar_t
   const false private this while
   constexpr float protected thread_local
   const_cast for public throw

Furthermore, some identifiers shall not be used:

Furthermore, the alternative representations shown in Table 5 for certain operators and punctuators (2.6) are reserved and shall not be used otherwise:

Table 5 — Alternative representations

and and_eq bitand bitor compl not
not_eq or or_eq xor xor_eq

Even furthermore, as per 2.11 Identifier [lex.name], some are illegal to use, but the compiler is not required to tell you:

some identifiers are reserved for use by C++ implementations and standard libraries (17.6.4.3.2) and shall not be used otherwise; no diagnostic is required

— Each name that contains a double underscore _ _ or begins with an underscore followed by an uppercase letter (2.12) is reserved to the implementation for any use.

— Each name that begins with an underscore is reserved to the implementation for use as a name in the global namespace.