Allow use of int128\uint128 type in enums

[0xF6]

Flags support would be nice too.

[huoyaoyuan]

This is not an actionable C# feature .

Enum base type requires a way to encode the constant values, representation in type system, and support in reflection, debug tools etc. Currently only ECMA-335 primitive types are possible.

This can only be implemented by user defined type-based enum, which is not in scope for now.

[0xF6]

Currently only ECMA-335 primitive types are possible.

Why?
New versions of C# already violate a lot of ECMA features, what's the problem then?

[HaloFour]

It's actionable, but it does require that the runtime add support for those types in enums otherwise the type would fail to load.

[huoyaoyuan]

New versions of C# already violate a lot of ECMA features, what's the problem then?

There isn't violations, but mostly extensions.
It's also quite a little.

Enums are closely integrated to the type system, especially COR_ELEMENT_TYPE which is effectively frozen.