Add DateIOnly/TimeOnly support to XmlSerializer and DataContractSerializer

[eiriktsarpalis]

Are XmlSerializer and DataContractSerializer also going to be supported?

Originally posted by @LaughingJohn in #51302 (comment)

[drieseng]

@eiriktsarpalis Is this one up for grabs? Not committing to anything yet, but I may have some time (and interest) for this.

[eiriktsarpalis]

I defer to the area owners of serialization cc @StephenMolloy

[ThaDaVos]

It seems, almost 2 years later, this hasn't picked up yet sadly

[kirsan31]

Yes, I was very surprised to find this problem. 😯

[JosepBalague]

Still failing in 7.0.306

Despite forcing new types like that XmlSerializer ser = new(typeof(MyClass), new Type[] { typeof(DateOnly), typeof(TimeOnly) });
code fails. Please watch output:

<?xml version="1.0" encoding="utf-16"?> <MyClass xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Value_do /> <--- MISSING VALUE <Value_to /> <--- MISSING VALUE <Value>2023-07-12T17:05:37.4485796+02:00</Value> </MyClass>

I attach the code.

Cheers
Serialize_MS.zip