Treat .NET 7 `required` properties as actually required by default

[DoctorKrolic]

Code snippet:

public class Options
{
    [Option]
    public required int Port { get; init; }

    [Option]
    public required string Server { get; init; }
}

Expected behaviour: Both Port and Server are required and the parsing fails if at least on of them is not present.

Actual behaviour: They are not required, I still have to specify [Option(Required = true)] in order for it to work

[Orace]

Using sharplab.io, it appears that a RequiredMemberAttribute is added to the required properties.

Search for this attribute is a trivia.

[Orace]

Has mentioned by DoctorKrolic here

What if you have a required modifier and [Option(Required = false)]? I would say, it should throw because of conflicting settings. Please add test for such case

Required = false is the default case, hence, if we implement this, it will throw on default case.

1. We can make Required = true mandatory on required properties, which is redundant and against the purpose of this issue (Treat .NET 7 required properties as actually required by default).

2. We can change the type of the Required attribute property to a try-state (unset, true, false) with an unset default value, which will be treated:

   • as true in the case of a required property
   • as false in other cases

3. We can stay silent and ignore Required = false on required properties.

Option 2 looks pretty, but we must validate that it is not a breaking change (see this Jon Skeet post where he talk about the optional parameters). Does a bool? do the trick?

[DoctorKrolic]

Required = false is the default case, hence, if we implement this, it will throw on default case.

Uh, I see...

Does a bool? do the trick?

Having Required as a bool? can really be a win, so we infer null state to true if the property is required and false otherwise. I am afraid, this is a binary breaking change though...

[Orace]

A quick look to the IL shows it unfortunately is 😒