Service-fabric: Unable to use feature 'default literal' (c# 7.1)

[vshaukun]

Visual Studio (15.7.2) compile successfully, but msbuild fails

Web1.csproj (LangVersion is 7.1)

[Route("api/[controller]")]
public class ValuesController : Controller
{
    private readonly MyService myService;
    public ValuesController()
    {
        myService = new MyService();
    }
    // GET api/values/5
    [HttpGet("{id}")]
    public int Get(int id)
    {
        return myService.GetDefaultValue();
    }
}

services.csproj (LangVersion is 7.1)

public class MyService
{
    public int GetDefaultValue()
    {
        int value = default;
        return value;
    }
}

msbuild output:

"C:\Temp\testSF\testSF\testSF.sfproj" (Package target) (1) ->
"C:\Temp\testSF\Web1\Web1.csproj" (default target) (2:5) ->
"C:\Temp\testSF\services\services.csproj" (default target) (3:6) ->
(CoreCompile target) ->
MyService.cs(9,25): error CS8107: Feature 'default literal' is not available in C# 7.0. Please use language version 7.1 or greater. [C:\Temp\testSF\services\services.csproj]

added
It is possible to use 'default' in the Web1.csproj, but not in the services.csproj

[vshaukun]

testSF.zip

1. go to gulp folder and run npm i
2. run gulp build

[aL3891]

What version of msbuild are you running? the one included in VS?

[vshaukun]

Yes, included in VS

[jtapolczai]

I had the same problem a while back and was able to solve it by editing the .sfproj and packages.config-files in the Service Fabric project.

Per default, the older Msbuild 1.6.2 is required, which doesn't support C# 7.1, but if you change this everywhere to Msbuild 1.6.6, the C# 7.1 features should work.

packages.config:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Microsoft.VisualStudio.Azure.Fabric.MSBuild" version="1.6.6" targetFramework="net461" />
</packages>

.sfproj (also do a replace of "1.6.2" with "1.6.6"):

...
<SupportedMSBuildNuGetPackageVersion>1.6.6</SupportedMSBuildNuGetPackageVersion>
...

[JamiePed]

I am also experiencing something similar to this problem myself.

I am able to build and deploy the solutions locally in Visual Studio, however on my VSTS Build Agent (which should be using exactly the same version of Visual Studio) I get the error above.

Relatively interestingly I don't get this on the Build Solution Step, only on the Build *.sfproj step after it. Below are screen shots of my build step. I have done what was suggested by @jtapolczai but that hasn't helped.

Has anyone else had a similar problem?

[nicolas-garcia]

Hello,
I have the exact same issue as @JamiePed
If I open the solution and manually package the application using Visual Studio 2017 on the build agent, it works.
But, through VSTS task, it fail.

My packages.config target MSBuild 1.6.7 :
<package id="Microsoft.VisualStudio.Azure.Fabric.MSBuild" version="1.6.7" targetFramework="net471" />

The temporary workaround is ... to not use C# 7.1 features 😞

[vitalsap]

This can be solved by checking these nodes in project files.
<TargetFrameworkVersion>v4.7.1</TargetFrameworkVersion> <LangVersion>7.3</LangVersion> <TargetFramework>netstandard2.0</TargetFramework>
These properties should be compatible to use C# 7.1 features.

@JamiePed check your erroring project has the lang version specified. And <LangVersion> should be in the first/main <PropertyGroup> of the project file. Otherwise it will not get from the VSTS build flow but in the Visual Studio.

[kensaccord]

I ran into this issue when targeting a *.proj. The issue was on VSTS Platform type. It use to build with the type set to "any cpu", and now if you are targeting a *.proj file you must specify "AnyCPU" (no whitespaces)

[cosminsandu25]

You only need to add the <LangVersion>7.3</LangVersion> tag the projects that fails and everything will work.

[demonguru18]

Here try this => int value = default(value);

public class MyService
{
    public int GetDefaultValue()
    {
        int value = default(value);
        return value;
    }
}

[KSemenenko]

Why does this not work like in VS where the maximum version is taken by default?

[dbr123]

have the problem yesterday in VS 2017, only resolved it by moving to VS 2019...

[SamHard]

I think I found a solution for msbuild, and I see that @kensaccord mentioned the same fix, above. I had the same issue as @JamiePed and @nicolas-garcia, except that the DevOps build task was giving me an error about C# 8, like this: "Error CS8370: Feature '[X]' is not available in C# 7.3. Please use language version 8.0 or greater." Per this Azure DevOps page on the Visual Studio Build task:

Platform: If you are targeting an MSBuild project (.*proj) file instead of a solution, specify AnyCPU (no whitespace).

So, in the Visual Studio Build task configuration, I changed the Platform setting from "$(BuildPlatform)" to "AnyCPU", and the build succeeded. (The default value was "Any CPU".)

By the way, for those not using Azure DevOps (or if you want to test locally with msbuild), that setting corresponds with the /p:platform="AnyCPU" parameter in msbuild.exe.