VS Code Support: Let user choose LangVersion instead of defaulting to "latest"

Unity Engine
,
1

There isn’t a dedicated forum for VSCode editor support, so I am posting here hoping that any Unity staff could see and point it to the right people.

My feedback/feature request is to let the user choose what LangVersion is used in csproj file, so that VSCode C# extension could provide relevant information.

The official C# extension of VSCode is way ahead of Unity in language feature support – they already moved on to C# 9. Because of this, the latest version of C# LangVersion is now “9.0”. However, the generated C# project by Unity specifies LangVersion as “latest” and thus VSCode C# defaults the language to 9.0 and suggesting code fixes in C# 9 that Unity’s C# 8 compiler does not yet recognize. For example, pattern matching:

// Original code:
Notification notification = args.Context as Notification;
if (notification == null)
    return;

// LangVersion: latest
// Code fix with C# 9 feature:
if(args.Context is not Notification notification)
    return;

However, VSCode C# extension already supports different code fixes based on LangVersion. If I change manually LangVersion to “8.0” in csproj file:

 <PropertyGroup>
    <LangVersion>8.0</LangVersion>
  </PropertyGroup>

The code fix becomes:

// Older C# code fix:
if(!(args.Context is Notification notification))
     return;

There could be other use cases for this new feature, say if someone wants to limit themselves to use a specific language version in order to maintain source compatibility with some other older Unity projects, like Asset Stores authors.

2 Likes
2

This is definitely an issue for me also!

1 Like
3

I’m not sure, but I think Unity partially supports C# 9 features that don’t need runtime support, but I can be mistaken and confused with C# 8, which will not be fully supported until 2021.2.

4

Created an issue for this problem at github repo of the VSCode-support package: https://github.com/Unity-Technologies/com.unity.ide.vscode/issues/12

1 Like