在 NetCoreApp 中使用 Roslyn：未安装 MSBuildWorkspace

Question

I am trying to learn how to use Roslyn to extract info from c# source files. But I can't even get started, because I can't seem to find the right way to install the right packages.

I'm trying to build a simple netcoreapp1.1 console app. Its csproj file looks like this:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp1.1</TargetFramework>
    <PackageTargetFallback>portable-net45+win8</PackageTargetFallback>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis" Version="2.0.0" />
    <PackageReference Include="Microsoft.Composition" Version="1.0.30" />
  </ItemGroup>

</Project>

I thought from what I'd read online that this would be sufficient to load whatever assembly contains MSBuildWorkspace...but apparently not.

How do I go about getting the project configured properly?

Answer 1

Unfortunately, MSBuildWorkspace is currently only supported on .Net Framework . You won't be able to use it from .Net Core.

Answer 2

The accepted answer seems no longer up to date: there is a NuGet package Microsoft.CodeAnalysis.Workspaces.MSBuild that supports .NET Core Console Apps:

Trying out that package with these lines:

using Microsoft.CodeAnalysis.MSBuild;
...
var workspace = MSBuildWorkspace.Create();
var solution = workspace.OpenSolutionAsync(solutionFile.FullName).Result;

... it threw an exception. I found a posting ( https://github.com/dotnet/roslyn/issues/17401#issuecomment-282605950 ) that added a few other NuGet packages that seem to be dependencies. That made the references in my csproj:

<PackageReference Include="Microsoft.Build" Version="16.7.0" />
<PackageReference Include="Microsoft.Build.Framework" Version="16.7.0" />
<PackageReference Include="Microsoft.Build.Tasks.Core" Version="16.7.0" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.7.0" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="3.7.0" />
<PackageReference Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="3.7.0" />

and with these references I got it to work (I'm working on Windows).

However, I ran into the issue that that Microsoft.CodeAnalysis.Project's Documents Count was 0 and someProject.GetCompilationAsync().Result.SyntaxTrees was null. The "MSBUILD_EXE_PATH" is not correctly set (see https://github.com/dotnet/roslyn/issues/22415 ). At first I chose to set the most recent MSBuild.dll this way:

    private static void SetMSBuildPath()
    {
        var latestSdk = new DirectoryInfo(@"C:\Program Files\dotnet\sdk\").EnumerateDirectories().Where(f => Regex.IsMatch(f.Name, @"\d+\.\d+\.\d+"))
            .OrderByDescending(f => f.Name.Split(".")[0])
            .ThenByDescending(f => f.Name.Split(".")[1])
            .ThenByDescending(f => f.Name.Split(".")[2])
            .FirstOrDefault();

        Environment.SetEnvironmentVariable("MSBUILD_EXE_PATH", Path.Combine(latestSdk.FullName, "MSBuild.dll"));
    }

but a better way is to use the NuGet package Microsoft.Build.Locator and invoke it at the start of your application once like this:

MSBuildLocator.RegisterDefaults();

For this to work, make sure that you exclude MSBuild from the Microsoft.Build.* NuGet packages you use (except from Microsoft.Build.Locator ) as suggested by the documentation (this changes the PackageReferences shown above):

<PackageReference Include="Microsoft.Build" Version="16.7.0" ExcludeAssets="runtime" />
<PackageReference Include="Microsoft.Build.Framework" Version="16.7.0" ExcludeAssets="runtime" />
<PackageReference Include="Microsoft.Build.Locator" Version="1.2.6" />
<PackageReference Include="Microsoft.Build.Tasks.Core" Version="16.7.0" ExcludeAssets="runtime" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.7.0" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="3.7.0" />
<PackageReference Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="3.7.0" />

PS: I haven't looked into it, but maybe https://github.com/daveaglick/Buildalyzer (NuGet package "Buildalyzer") solves all of these problems.