Enum with associated fields

[bernardnormier]

This PR implements enum with (associated) fields in C#.

The C# mapping relies on Dunet (https://github.com/domn1995/dunet). A nice feature of Dunet is it's 100% a source generator. The resulting code does not depend on a Dunet assembly at runtime.

Not implemented in this PR (but should be implemented in a follow-up PR):

• enumerator fields doc-comments
• name-escaping when an enumerator is named 'Unknown' in an unchecked enum
• name-escaping when an enumerator field is named 'Discriminant'
• encoding for compact enum

Note that discriminants are encoded as varint32 (not varuint32), just like tag values.

[pepone]

Dunet is it's 100% a source generator. The resulting code does not depend on a Dunet assembly at runtime.

Does this mean the Dotnet development dependency is only required when you define enums with associated fields?

[bernardnormier]

Dunet is it's 100% a source generator. The resulting code does not depend on a Dunet assembly at runtime.

Does this mean the Dotnet development dependency is only required when you define enums with associated fields?

Yes. But it's Dunet with a 'u'.