Allow use of Decimal type in enums

[john-h-k]

Allow use of Decimal / decimal type in enums, as such:

public enum MyEnum : decimal
{ }

The primary motivation for this is that it would allow easy implementation of FlagsAttribute style enum to have 128 indepedently XOR-able flags, as opposed to the current 64 bit limit (Int64 / long)

[tannergooding]

This would require a runtime change in order for it to be a valid enum type (and meet the System.Enum constraint).

[YairHalberstadt]

If you genuinely need more than 64 different values for a flags enum, perhaps it would be ideal to try and break it up into 2 flags?

[fanoI]

Probably will be better to have a proper (U)Int128 type with full language support (ability to declare constant literals, to declare them in enum's and so on...).

[YairHalberstadt]

@fanol
That would be useful for creating genuinely unique hashes. With longs you can't avoid the chance of a conflict even with a perfect hash, but with 128 bits, the chance is so small it's practically irrelevant (so long as your hashing algorithm is actually perfect, which is the big if)

[YairHalberstadt]

Of course though, writes and reads would not be atomic

[yaakov-h]

@YairHalberstadt we'll just have to build 128-bit processors then...

[YairHalberstadt]

@yaakov-h
Sounds like a plan