Proposal: Throw exception in null-coalescing operator

[lachbaer]

I think that there are often times where one would like to throw an exception if a value is null, like in

public string {
    get { return _myString; }
    set {
        if (value!=null) _myString = value;
        throw new ArgumentNullException();
    }
}

When allowing to throw an exception in the ?? Operator then things could be less verbose, but also quite understandable to everyone.

public string {
    get { return _myString; }
    set { _myString = value ?? throw new ArgumentNullException(); }
}

[alrz]

Dupe of #5143 (see 3rd point under "allowed in only the following contexts").

[lachbaer]

Ah, I see that it is already completely written down in https://github.com/dotnet/roslyn/blob/future/docs/features/patterns.md.
(Did my research, but didn't see the forrest because of all the trees ;-)