Private primary constructors

[flakey-bit]

Wondering whether we've considered the possibility of allowing primary constructors to be private. It might help with protecting invariants

For example, we have a type here that wants to protect the invariant that the GUID it wraps being not equal to Guid.Empty:

public class NotEmpty(Guid Value)
{
    public static NotEmpty Create(Guid value) => value == Guid.Empty
        ? throw new ArgumentException("Value must not be empty", nameof(value))
        : new NotEmpty(value);
}

At the call site:

var y = new NotEmpty(Guid.Empty);        // Invariant not protected
var z = NotEmpty.Create(Guid.Empty);    // Invariant protected

If the primary constructor was private, we could enforce creation via the static factory, preserving the invariant.

NB: Not quite sure how this should behave for record types