Parameter Null Checking & CallerArgumentExpression

[BOBJohnson]

I don't know if this is the correct place to post this. Apologies if it is not.

I love the idea of the Parameter Null Checking feature (https://github.com/dotnet/csharplang/blob/main/proposals/param-nullchecking.md) in the works.

I also like the fairly new CallerArgumentExpression and can provide some extremely useful information in tracking down problems, such as when an argument is null and it should not be.

I have no idea if this is even remotely feasible, but I would love for the new !! operator to be combined with CallerArgumentExpression attribute.

For example:

void M(string name!!) {
    ...
}

Would emit:

void M(string name, [CallerArgumentExpression("name")] string? nameExpression = null) {
    if (name is null) {
        throw new ArgumentNullException(nameExpression);
    }
    ...
}

Edit: fixed the missing string? from the method parameters.

[svick]

That feature has been removed from C# 11 and is currently not planned to be included in a future version of C#.