Add Unity.Mathematics support

[KonH]

Fixes #1603
(will be appreciated for hacktoberfest-approved label)

[neuecc]

This PR would cause problems in an environment where Unity.Mathematics is not installed.
And is it only int2?

[KonH]

Hmm, that's right, we need the ability to check availability somehow, it's better in a compile-time context.
I added only int2 just to minimize iteration time, it's possible to add other types later when the whole integration circle is passed.

[neuecc]

You can use define like this?
https://github.com/Cysharp/UniTask/blob/master/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTask.asmdef#L12-L43

[KonH]

It looks like a solution. I will try it, thanks!

[KonH]

I've added conditional package reference, and plan to think about more formatters little bit later

[KonH]

I've added the most common types from that package, I think it's enough for initial support

[neuecc]

thanks, I'll check soon.

[KonH]

And also, could you please mark that PR with label hacktoberfest-accepted?
It's required for Hacktoberfest participation, as described here - https://hacktoberfest.com/participation/#pr-mr-details

[KonH]

Any updates?

[neuecc]

Sorry for delayed review, I've checked.
It's almostly ok.
However, still exists "references": ["Unity.Mathematics"] in asmdef.
This is a soft reference and is usually ignored if there is no reference, so there is no problem.

However, I recall that in the past such references have caused problems in dependency resolve.
Cysharp/UniTask#98
Therefore, could you please separate the assemblies?
Like MessagePack.UnityMathmatics.

[KonH]

I've tried to do it and it looks like a vast refactoring:

• Move Unity.Mathematics formatters from Assets/Scripts/MessagePack/Unity/Formatters.cs require references to IMessagePackFormatter
• IMessagePackFormatter is located in Formatters namespaces -> new asmdef is required
• IMessagePackFormatter requires MessagePackReader, MessagePackWriter, etc
• MessagePackReader, MessagePackWriter are core classes -> more asmdefs are required

So it leads to big diff and I'm not sure it really wanted changes.
What do you think? Maybe I did not correctly understand you?

[AArnott]

@neuecc In light of #1734, do you have any fresh ideas for this?

[neuecc]

I think it would be better to add it as a UnityMathmaticsResolver and move towards compositing it, rather than including it in UnityResolver.