WithEnforceNullability doesn't seem to have an effect with F# records

[reinux]

Describe the bug
In F#, WithEnforceNullability has an effect on classes but not on records.

To Reproduce
In fsi:

#r "nuget: YamlDotNet
open YamlDotNet.Serialization
open YamlDotNet.Serialization.NamingConventions

let deserializer =
  DeserializerBuilder().WithNamingConvention(CamelCaseNamingConvention.Instance)
    .WithEnforceNullability()
    .Build()
    
[<CLIMutable>]
type SomeRecord = {
  Age: int
  Name: string
}

type SomeClass() =
  member val age = 999 with get, set
  member val name = "" with get, set

// Defaults Age to 999
deserializer.Deserialize<SomeClass> """
  Name: Blargh
"""

// Defaults Age to 0
deserializer.Deserialize<SomeRecord> """
  name: Blorgh
"""

[reinux]

Sorry, hang on, I got the repro wrong.

[reinux]

Actually, I'm not sure how this would work with classes even, given that it isn't using a constructor to instantiate types. I might be misunderstanding what WithEnforceNullability does.

[EdwardCooke]

Enforce means that when a property is set it will check if that property has the allow null attribute or not and if the value being set is null. If the value is null and the allow null attribute is not there, it’ll throw an exception.

The way yamldotnet creates objects (records, classes, structs, whatever) is by calling the default parameter less constructor using a .net built in type activator.

Because you never set the age to 999 in your record it will be 0. I also dont think we have any tests for f# and enforcenullability so it may or may not even work as expected.

[reinux]

Got it. WithEnforceRequiredMembers is what I was looking for. Not sure why I thought there wouldn't be a distinction between null and missing.

That said, neither of those seem to have an effect in F#, which is weird because as far as the CLR is concerned they just compile down to regular classes and properties with some extra attributes. Inspecting the fields using GetType(), they do have the attributes assigned as you'd expect.

let deserializer =
  DeserializerBuilder()
    .WithEnforceNullability()
    .WithEnforceRequiredMembers()
    .Build()

[<CLIMutable>]
type T = {
  [<System.Diagnostics.CodeAnalysis.AllowNull>]
  x: int
  y: int
  [<System.ComponentModel.DataAnnotations.Required>]
  z: int
}

deserializer.Deserialize<T> """
x: null
y: null
"""

I fully qualified the attributes just so it's clear which ones I'm using. I'm assuming they're correct?