How do I make VSCode use C# 7 instead of C# 4?

Question

My VSCode debugger says that I'm using c# 4. I can't find any docs about getting VSCode to switch to C# 7. I'm on Windows 10. I don't know if this is a DotNet Core issue, a VSCode issue, or an Omnisharp issue. I would appreciate someone pointing me to a set of instructions or posts that solved this problem.

A snipet from the top of my VSCode .csproj file:

    <?xml version="1.0" encoding="utf-8"?> <Project ToolsVersion="4.0" 
    DefaultTargets="Build" 
    xmlns="http://schemas.microsoft.com/developer/msbuild/2003"> 
    <PropertyGroup> <LangVersion>4</LangVersion> </PropertyGroup> 
    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion> 

These are my VSCode versions:

    Version: 1.27.2 (user setup) 
    Commit: f46c4c469d6e6d8c46f268d1553c5dc4b475840f 
    Date: 2018-09-12T16:17:45.060Z
    Electron: 2.0.7 
    Chrome: 61.0.3163.100 
    Node.js: 8.9.3 V8: 6.1.534.41
    Architecture: x64 
    .NET Core SDK version 2.1.402 (x64)

Answer 1

As you've pointed out in the portion of your question where you posted the csproj, the current language version is set to 4.

<LangVersion>4</LangVersion>

You can get the latest features for C# 7.3 by setting it to <LangVersion>7.3</LangVersion>

If you merely want the C# 7.0 features, you can set the value to <LangVersion>7</LangVersion>

This document lists the (currently) valid options that can be passed to the -langversion compiler flag. If you want your project to always compile with the latest available version of C#, you can set the value to <LangVersion>latest</LangVersion> in your .csproj. Of course, this will only compile to the latest version supported by your version of the compiler.

The behavior of the default value has changed in recent versions of the compiler. The document accurate at the time of editing is this one, which states the following:

The compiler determines a default based on these rules:

Target framework	Version	C# language version default
.NET Core	6.x	C# 10.0
.NET Core	5.x	C# 9.0
.NET Core	3.x	C# 8.0
.NET Core	2.x	C# 7.3
.NET Standard	2.1	C# 8
.NET Standard	1.x/2.0	C# 7.3
.NET Framework	all	C# 7.3

Answer 2

You just need to update your

<PropertyGroup> <LangVersion>4</LangVersion> </PropertyGroup> 

To the version you want