Roslyn Code Analysis returns false build errors from an error free solution

Question

I try to use Roslyn to analyze a very simple C# solution, a console application with a simple skeleton program:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CA5
{
    class Program
    {
        static void Main(string[] args)
        {
        }
    }
}

The code above builds without any error in VS 2019 Preview. For such a simple solution/program I expected the Roslyn CA to work without any glitches, however the Roslyn compilation returns errors, most having to do with unrecognized type.

My CA code is this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.MSBuild;

namespace CA5X
{
    class Program
    {
        static void Main(string[] args)
        {
            const string path = @"C:\Utils\CA5\CA5.sln";

            var props = new Dictionary<string, string>();
            props["CheckForSystemRuntimeDependency"] = "true";
            MSBuildWorkspace buildWorkspace = MSBuildWorkspace.Create(props);

            Solution solutionToAnalyze = buildWorkspace.OpenSolutionAsync(path).Result;
            foreach (Microsoft.CodeAnalysis.Project sProject in solutionToAnalyze.Projects)
            {
                Compilation sCompilation = sProject.GetCompilationAsync().Result;
                var errors = sCompilation.GetDiagnostics().Where(d => d.Severity == DiagnosticSeverity.Error); 

                Console.WriteLine("COUNT:  " + errors.Count().ToString());

                foreach (Microsoft.CodeAnalysis.Diagnostic diagnostic in errors)
                {
                    Console.WriteLine(diagnostic.GetMessage());
                }

            }
        }
    }
}

The diagnostics retrieved after compilation are these:

The type or namespace name 'AssemblyTitleAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyTitle' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyDescriptionAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyDescription' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyConfigurationAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyConfiguration' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyCompanyAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyCompany' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyProductAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyProduct' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyCopyrightAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyCopyright' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyTrademarkAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyTrademark' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyCultureAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyCulture' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'ComVisibleAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'ComVisible' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'GuidAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'Guid' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyVersionAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyVersion' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyFileVersionAttribute' could not be found (are you missing a using directive or an assembly reference?)
The type or namespace name 'AssemblyFileVersion' could not be found (are you missing a using directive or an assembly reference?)
Predefined type 'System.String' is not defined or imported
The type or namespace name 'System' could not be found (are you missing a using directive or an assembly reference?)
Predefined type 'System.Object' is not defined or imported
Predefined type 'System.String' is not defined or imported
Predefined type 'System.Void' is not defined or imported
'object' does not contain a constructor that takes 0 arguments

I can only guess that this happens because of some configuration issue, but with so many .NET versions and so many VS versions is impossible to try all combinations.

Answer 1

I would like to thank you for the suggestions.

Eventually I have found that the problem was caused by a confused use of nuget packages. My project was initially aimed to DotNet Framework 4.5.2, then I added some nuget packages, VS switched automatically to 4.7.2 and I ended up with a wrong combination of libraries. As I was not experienced in using nuget, I did not realize that one can also pick a specific version compatible with the targeted DotNet frame.

With enough care I succeeded in creating the correct combination of packages, then it all worked fine.

Answer 2

If you setup your project to use the MSBuildLocator like below it should be able to load your project:

SampleRoslynTool.csproj:

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

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net472</TargetFramework>
    <LangVersion>Latest</LangVersion>
  </PropertyGroup>

   <ItemGroup>
    <PackageReference Include="Microsoft.Build.Locator" Version="1.2.6" />
    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="2.9.7" PrivateAssets="all" />
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="3.3.1" />
    <PackageReference Include="Microsoft.CodeAnalysis.VisualBasic.Workspaces" Version="3.3.1" />
    <PackageReference Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="3.3.1" />
  </ItemGroup>

</Project>

Program.cs:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Build.Locator;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Symbols;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.MSBuild;
using Microsoft.CodeAnalysis.Text;

namespace SampleRoslynTool
{
    class Program
    {
        static async Task Main(string[] args)
        {
            // Attempt to set the version of MSBuild.
            var visualStudioInstances = MSBuildLocator.QueryVisualStudioInstances().ToArray();
            var instance = visualStudioInstances.Length == 1
                // If there is only one instance of MSBuild on this machine, set that as the one to use.
                ? visualStudioInstances[0]
                // Handle selecting the version of MSBuild you want to use.
                : SelectVisualStudioInstance(visualStudioInstances);

            Console.WriteLine($"Using MSBuild at '{instance.MSBuildPath}' to load projects.");

            // NOTE: Be sure to register an instance with the MSBuildLocator 
            //       before calling MSBuildWorkspace.Create()
            //       otherwise, MSBuildWorkspace won't MEF compose.
            MSBuildLocator.RegisterInstance(instance);

            using (var workspace = MSBuildWorkspace.Create())
            {
                // Print message for WorkspaceFailed event to help diagnosing project load failures.
                workspace.WorkspaceFailed += (o, e) => Console.WriteLine(e.Diagnostic.Message);

                var solutionPath = args[0];
                Console.WriteLine($"Loading solution '{solutionPath}'");

                // Attach progress reporter so we print projects as they are loaded.
                var solution = await workspace.OpenSolutionAsync(solutionPath, new ConsoleProgressReporter());
                Console.WriteLine($"Finished loading solution '{solutionPath}'");

                // TODO: Do analysis on the projects in the loaded solution
            }
        }

        private static VisualStudioInstance SelectVisualStudioInstance(VisualStudioInstance[] visualStudioInstances)
        {
            Console.WriteLine("Multiple installs of MSBuild detected please select one:");
            for (int i = 0; i < visualStudioInstances.Length; i++)
            {
                Console.WriteLine($"Instance {i + 1}");
                Console.WriteLine($"    Name: {visualStudioInstances[i].Name}");
                Console.WriteLine($"    Version: {visualStudioInstances[i].Version}");
                Console.WriteLine($"    MSBuild Path: {visualStudioInstances[i].MSBuildPath}");
            }

            while (true)
            {
                var userResponse = Console.ReadLine();
                if (int.TryParse(userResponse, out int instanceNumber) &&
                    instanceNumber > 0 &&
                    instanceNumber <= visualStudioInstances.Length)
                {
                    return visualStudioInstances[instanceNumber - 1];
                }
                Console.WriteLine("Input not accepted, try again.");
            }
        }

        private class ConsoleProgressReporter : IProgress<ProjectLoadProgress>
        {
            public void Report(ProjectLoadProgress loadProgress)
            {
                var projectDisplay = Path.GetFileName(loadProgress.FilePath);
                if (loadProgress.TargetFramework != null)
                {
                    projectDisplay += $" ({loadProgress.TargetFramework})";
                }

                Console.WriteLine($"{loadProgress.Operation,-15} {loadProgress.ElapsedTime,-15:m\\:ss\\.fffffff} {projectDisplay}");
            }
        }
    }
}