Would the Roslyn Compiler compile C# 8.0 preview?

I mean, I've been using Unity 2018.3 since the first beta for production, as it has always been for me. I really like the not-so-new already C# 7.0/1/2/3 features, but would the RC compile the preview version of the language (C# 8.0) that was released recently? It's just for the curiosity that I'm asking.

Also, Unity says that the supported .NET Framework version is 4.x. Does that already include 4.8? Thanks.

 

What about trying and see if it works?

 

I was hoping that someone had an answer already! xD

 

Well, it could be you to be the first to know and tell the others.

 

I just tested it. The C# 8.0 is only available on Visual Studio 2019 preview, which isn't compatible with Unity yet, apparently. I could be mistaken and have done something wrong, but I have no way of knowing if C# 8 does work with Unity because the VS version required doesn't in my hands. Sadface.

Also, Unity doesn't support .NET 3.x Core preview. Sadface again. That's needed to compile C# 8.0, so I guess Unity can't compile C# 8.0 yet. I'm one of those guys, I want new features before they get invented/released.

 

I thought people had managed installing Visual Studio 2019 and have it work with Unity; maybe it was Unity 2019.1?

 

Maybe, I have no idea whatsoever. I'm not using an Alpha editor for production anyways. I'm testing it when it gets to Beta.

 

https://forum.unity.com/threads/visual-studio-2019.592858/

 

This is a 2018.3.0f2 project with integrated Roslyn v2.11.0.63519 (C# 8 beta) - https://dl.dropbox.com/s/insuh1830wfttk9/CSharp8.zip

• Nullable reference types - ok
• Ranges and indices - ok
• Asynchronous streams - not yet, current mono runtime lacks some important core types and there's no easy way to add them externally

Not for production, obviously. Just for fun.

 

If I could whistle via text, I would.

EDIT: I know why I couldn't use VS19 with Unity. That's because sometimes I'm silly. I totally forgot to install the Unity Extension (or Tools or something like that) with VS. It's working perfectly now. Hurray!

 

This is a 2018.4.3f1 project with integrated Roslyn 3.200.19.31205 taken from the latest Visual Studio 2019 version 16.2 Preview 3. You might also need to use that exact version of Visual Studio. I'm not sure it would work fine with older versions.

https://dl.dropbox.com/s/izxjalqunrxlxei/CSharp8-2.zip

Just for fun.

 

@alexzzzz Using that means we lose the "incremental-ness" of the built-in one, right?

I wish they had open sourced their changes so we could easily replace/modify anything to test out new features.

 

I doubt the stock compiler is incremental, is it?

 

Oh, I though it was? They deprecated the "incremental compiler package" stating that the interesting parts were ported over to the built-in one. It should also be somewhat parallel (independent asmdef stuff is compiled in parallel)

Or maybe am crazy? I'll have to do some tests later.

---

Alright, just tried to test but could not get it to work on 2019.3.0a8 (I did unblock the zip).
Unity kept unloading the DLL because "this assembly can cause crashes in the runtime".
I'll try to play with it a bit more when I have some free time.

 

Maybe I'm wrong, I remember it like "Here is our new compiler. It's not incremental, but works faster (or not slower) and almost as good as the incremental one which is now deprecated."

I suspect that the stock compiler now is just Roslyn running on NET Core as a self-contained application. The Editor\Data\Tools\Roslyn folder looks like it is.

 

Yeah, maybe you're right.
I remember trying to replace the Roslyn folder just to see if it would work, and it broke.
But maybe that's because something else is compiled against a specific version of some library and that was what actually broke. The error messages were not helpful so I'm not sure.

With the incremental compiler, I had a script that would fetch the latest Roslyn from GitHub and update it directly, so I was trying to modify my script to update the actual bundled Roslyn Unity was shipping with.

Ah, I just remembered that I decompiled the csc and it was significantly different from Microsoft's, so maybe they are changing something.

I'll try to play around with it more when I have some extra time.

 

Yes, starting with Unity 2018.3.

https://forum.unity.com/threads/unity-incremental-c-compiler-deprecated.523993/page-10#post-3992170

 

Did anyone else play around with C#8 and Unity lately?
I just saw that the "Implicit Nullability" resharper/rider plugin will reach end-of-life soon (sometime next year) because nullable types in C#8 supersede its features, then I remembered this thread.


Here's their notice:

End-of-life note: C# 8, supported by VS 2019+, will get nullable reference types which supersede - and perfectly align with - Implicit Nullability. Therefore ReSharper/Rider < 2020.1 will be the latest version supported by Implicit Nullability.

And the reasoning, which is very fair. (Apologies for the screenshot, but I wanted the full github format)




I have a huge number of those NotNull and CanBeNull around.
I also have more complex contractAnnotations, but those can't be easily replaced by nullable reference types.

 

@alexzzzz Wouldn't it make sense to name folder CSharp80Support instead of CSharp70Support? In Rider we could have used it to guess the LangVersion.

 

Putting the language version in the name wasn't the best idea. I realized that once you guys started using it to detect the plugin and the C# guys releasing new 7.x versions every 6 months. I decided it's safer to leave is as it is, like System32 folder in 64-bit Windows. I should have realized that earlier, when 7.0 came out and my repository's name was https://bitbucket.org/alexzzzz/unity-c-5.0-and-6.0-integration.

There is langVersion.txt file inside CSharp70Support folder. It is generated when the plugin's editor dll is loaded:

Spoiler

Code (CSharp):

1. [InitializeOnLoad]
2. public static class CSharpVNextSupportActivator
3. {
4.     static CSharpVNextSupportActivator()
5.     {
6.         if (Directory.Exists(CustomCSharpCompiler.CSHARP_VNEXT_SUPPORT_DIR))
7.         {
8.             File.WriteAllText(Path.Combine(CustomCSharpCompiler.CSHARP_VNEXT_SUPPORT_DIR, "unityVersion.txt"), Application.unityVersion);
9.             File.WriteAllText(Path.Combine(CustomCSharpCompiler.CSHARP_VNEXT_SUPPORT_DIR, "langVersion.txt"), "8.0");
10.         }
11. ...

If it exists it should contain the most recent version of C# that the compiler is capable of, started with 7.2, then 7.3 and 8.0.

The 8.0 version, posted in this thread, was mostly for fun. I'm not sure there's much sense in continuing the plugin further, since there's no longer a 10-year gap between Unity's C# and normal people's C#. Unity coders are almost normal people now officially.