Automatically create IParseable<T> for enums

[msedi]

Currently Enum needs to be treated differently when parsing XML content.
For example we have a metehods that parses string from XML content, but need to leave the type completely open:

        public static T Parse<T>(string value)
        {
            if (TryParseInternal<T>(value, out var result, out var exception))
                return result;

            exception.Throw();
            return default;
        }

where it would be nice to simply express it like

public static T Parse<T>(string value) where T : IParseable<T>

However it seems that this is currently not possible.

If the IL for this enum

public enum Test
{
  A,
  B
}

this

.class public auto ansi sealed Test
    extends [System.Runtime]System.Enum
    implements class [System.Runtime]System.IParsable`1<valuetype Test>{
    // Fields
    .field public specialname rtspecialname int32 value__
    .field public static literal valuetype Test A = int32(0)
    .field public static literal valuetype Test B = int32(1)

} // end of class Test

would it make sense to automatically implement IParsable and implement the associated methods.
This would enable to treat Enums with IParsable in the context shown above and would also enable a more performant parsing as done by many source generators.

[huoyaoyuan]

As mentioned at dotnet/csharplang#9747 (comment), currently there's no way to do this at either side. Any API surface implemented "magically" by runtime must have corresponding metadata/contract in order to be understood by languages.