Remove RequiresUnreferencedCode from DefaultValueAttribute

[LakshanF]

This constructor of DefaultValue has RUC on it. This is likely due to a concern round converters with generic types (Nullable) which has been since fixed in the trimmer.

Tagging subscribers to this area: @dotnet/area-system-componentmodel
See info in area-owners.md if you want to be subscribed.

Issue Details

---

This constructor of DefaultValue has RUC on it. This is likely due to a concern round converters with generic types (Nullable) which has been since fixed in the trimmer.

Author:	LakshanF
Assignees:	-
Labels:	area-System.ComponentModel
Milestone:	-

[steveharter]

@LakshanF I assume you are proposing removing the RUC. Can you create a PR to do that? Thanks

Tagging subscribers to 'linkable-framework': @eerhardt, @vitek-karas, @LakshanF, @sbomer, @joperezr, @marek-safar
See info in area-owners.md if you want to be subscribed.

Issue Details

---

This constructor of DefaultValue has RUC on it. This is likely due to a concern round converters with generic types (Nullable) which has been since fixed in the trimmer.

Author:	LakshanF
Assignees:	-
Labels:	area-System.ComponentModel, linkable-framework
Milestone:	9.0.0

[vitek-karas]

The Nullable problem is actually only one of the reasons for RUC. Once you fix that, you'll notice that there's a secondary problem where the NullableConverter is calling TypeDescriptor.GetConverter for the underlying type:

runtime/src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/NullableConverter.cs

Line 34 in a78ddcc

UnderlyingTypeConverter = TypeDescriptor.GetConverter(UnderlyingType);

That method has RUC, and so we need to propagate it. I think this would only be fixable once we remove RUC on GetConverter.

[buyaa-n]

@LakshanF isn't it resolved? I don't see the RUC attribute now

[LakshanF]

Yes, #100821 removed the RUC from the constructor. But there is a RUC on its local function, and if the constructor is called, will result in a trimmer warning. The feature switch, _DefaultValueAttributeSupport, can be used to turn off the warning by setting the property to false (the default value of the property will be set to true)