Null value warning for default value of an enum through a generic

[ebfortin]

I have this code:

public class GammaDistributionModel<K> where K : Enum { K _shapeKind = default;

I get a warning for null value on default. However if I replace K with a valid Enum, I don't get that warning. I was expecting the compiler to infer that since K must be an enum then its default value is 0, it's a value type.

What am I missing?

[HaloFour]

A weird quirk of the runtime is that System.Enum itself is not a value type and it is also a legal generic type argument to that class. To fix that I suggest also adding struct as a generic constraint.

[FaustVX]

Yes to prove that:

Enum e = null;
e = E.A;

enum E
{
    A
}

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