[WIP] Updating MSBuild for the future

NuGet.Config

@@ -7,6 +7,7 @@
     <add key="nugetbuild" value="https://www.myget.org/F/nugetbuild/api/v3/index.json" />
     <clear/>
     <add key="buildtools" value="https://dotnet.myget.org/F/dotnet-buildtools/api/v3/index.json" />
+    <add key="cli-deps" value="https://dotnet.myget.org/F/cli-deps/api/v3/index.json" />
     <add key="NuGet" value="https://api.nuget.org/v3/index.json" />
   </packageSources>
 </configuration>

src/OmniSharp.Host/Program.cs

@@ -86,6 +86,23 @@ public static void Main(string[] args)
                 }
             }
 
+#if NET46
+            if (PlatformHelper.IsMono)
+            {
+                // Mono uses ThreadPool threads for its async/await implementation.
+                // Ensure we have an acceptable lower limit on the threadpool size to avoid deadlocks and ThreadPool starvation.
+                const int MIN_WORKER_THREADS = 8;
+
+                int currentWorkerThreads, currentCompletionPortThreads;
+                System.Threading.ThreadPool.GetMinThreads(out currentWorkerThreads, out currentCompletionPortThreads);
+
+                if (currentWorkerThreads < MIN_WORKER_THREADS)
+                {
+                    System.Threading.ThreadPool.SetMinThreads(MIN_WORKER_THREADS, currentCompletionPortThreads);
+                }
+            }
+#endif
+
             Environment = new OmnisharpEnvironment(applicationRoot, serverPort, hostPID, logLevel, transportType, otherArgs.ToArray());
 
             var config = new ConfigurationBuilder()

src/OmniSharp.Host/project.json

@@ -5,7 +5,6 @@
   },
   "dependencies": {
     "OmniSharp.Abstractions": "1.0.0",
-    "OmniSharp.Nuget": "1.0.0",
     "OmniSharp.Stdio": "1.0.0",
     "OmniSharp.Plugins": "1.0.0",
     "OmniSharp.Roslyn": "1.0.0",

src/OmniSharp.MSBuild/MSBuildProjectSystem.cs

@@ -180,6 +180,8 @@ private ProjectFileInfo AddProject(string filePath)
                 return null;
             }
 
+            _logger.LogInformation($"Add project: {fileInfo.ProjectFilePath}");
+
             _projects.Add(fileInfo);
 
             var compilationOptions = CreateCompilationOptions(fileInfo);
@@ -211,6 +213,24 @@ private static CSharpCompilationOptions CreateCompilationOptions(ProjectFileInfo
                 result = result.WithAllowUnsafe(true);
             }
 
+            var specificDiagnosticOptions = new Dictionary<string, ReportDiagnostic>(projectFileInfo.SuppressedDiagnosticIds.Count);
+
+            // Always suppress CS1701 (Assuming assembly reference 'x' used by 'y' matches identity 'z'. you may need to supply runtime policy)
+            specificDiagnosticOptions.Add("CS1701", ReportDiagnostic.Suppress);
+
+            if (projectFileInfo.SuppressedDiagnosticIds.Any())
+            {
+                foreach (var id in projectFileInfo.SuppressedDiagnosticIds)
+                {
+                    if (!specificDiagnosticOptions.ContainsKey(id))
+                    {
+                        specificDiagnosticOptions.Add(id, ReportDiagnostic.Suppress);
+                    }
+                }
+            }
+
+            result = result.WithSpecificDiagnosticOptions(specificDiagnosticOptions);
+
             if (projectFileInfo.SignAssembly && !string.IsNullOrEmpty(projectFileInfo.AssemblyOriginatorKeyFile))
             {
                 var keyFile = Path.Combine(projectFileInfo.ProjectDirectory, projectFileInfo.AssemblyOriginatorKeyFile);
@@ -330,7 +350,13 @@ private void UpdateSourceFiles(Project project, IList<string> sourceFiles)
                     continue;
                 }
 
-                // If not, add a new document.
+                // If the source file doesn't exist on disk, don't try to add it.
+                if (!File.Exists(sourceFile))
+                {
+                    continue;
+                }
+
+                // If all is OK, add a new document.
                 using (var stream = File.OpenRead(sourceFile))
                 {
                     var sourceText = SourceText.From(stream, encoding: Encoding.UTF8);
@@ -379,7 +405,10 @@ private void UpdateParseOptions(Project project, LanguageVersion languageVersion
 
         private void UpdateProjectReferences(Project project, IList<string> projectReferences)
         {
+            _logger.LogInformation($"Update project: {project.Name}");
+
             var existingProjectReferences = new HashSet<ProjectReference>(project.ProjectReferences);
+            var addedProjectReferences = new HashSet<ProjectReference>();
 
             foreach (var projectReference in projectReferences)
             {
@@ -394,7 +423,11 @@ private void UpdateProjectReferences(Project project, IList<string> projectRefer
                         continue;
                     }
 
-                    _workspace.AddProjectReference(project.Id, reference);
+                    if (!addedProjectReferences.Contains(reference))
+                    {
+                        _workspace.AddProjectReference(project.Id, reference);
+                        addedProjectReferences.Add(reference);
+                    }
                 }
                 else
                 {
@@ -411,6 +444,7 @@ private void UpdateProjectReferences(Project project, IList<string> projectRefer
         private void UpdateReferences(Project project, IList<string> references)
         {
             var existingReferences = new HashSet<MetadataReference>(project.MetadataReferences);
+            var addedReferences = new HashSet<MetadataReference>();
 
             foreach (var referencePath in references)
             {
@@ -427,8 +461,12 @@ private void UpdateReferences(Project project, IList<string> references)
                         continue;
                     }
 
-                    _logger.LogDebug($"Adding reference '{referencePath}' to '{project.Name}'.");
-                    _workspace.AddMetadataReference(project.Id, metadataReference);
+                    if (!addedReferences.Contains(metadataReference))
+                    {
+                        _logger.LogDebug($"Adding reference '{referencePath}' to '{project.Name}'.");
+                        _workspace.AddMetadataReference(project.Id, metadataReference);
+                        addedReferences.Add(metadataReference);
+                    }
                 }
             }
 

src/OmniSharp.MSBuild/ProjectFile/ProjectFileInfo.PropertyNames.cs

@@ -14,12 +14,14 @@ private static class PropertyNames
             public const string LangVersion = nameof(LangVersion);
             public const string OutputType = nameof(OutputType);
             public const string MSBuildExtensionsPath = nameof(MSBuildExtensionsPath);
+            public const string NoWarn = nameof(NoWarn);
             public const string ProjectGuid = nameof(ProjectGuid);
             public const string ProjectName = nameof(ProjectName);
             public const string _ResolveReferenceDependencies = nameof(_ResolveReferenceDependencies);
             public const string SignAssembly = nameof(SignAssembly);
             public const string SolutionDir = nameof(SolutionDir);
             public const string TargetFrameworkMoniker = nameof(TargetFrameworkMoniker);
+            public const string TargetFrameworkRootPath = nameof(TargetFrameworkRootPath);
             public const string TargetPath = nameof(TargetPath);
             public const string VisualStudioVersion = nameof(VisualStudioVersion);
         }

src/OmniSharp.MSBuild/ProjectFile/ProjectFileInfo.cs

@@ -30,6 +30,7 @@ public partial class ProjectFileInfo
         public string AssemblyOriginatorKeyFile { get; }
         public bool GenerateXmlDocumentation { get; }
         public IList<string> PreprocessorSymbolNames { get; }
+        public IList<string> SuppressedDiagnosticIds { get; }
 
         public IList<string> SourceFiles { get; }
         public IList<string> References { get; }
@@ -55,6 +56,7 @@ private ProjectFileInfo(
             string assemblyOriginatorKeyFile,
             bool generateXmlDocumentation,
             IList<string> defineConstants,
+            IList<string> suppressedDiagnosticIds,
             IList<string> sourceFiles,
             IList<string> references,
             IList<string> projectReferences,
@@ -73,6 +75,7 @@ private ProjectFileInfo(
             this.AssemblyOriginatorKeyFile = assemblyOriginatorKeyFile;
             this.GenerateXmlDocumentation = generateXmlDocumentation;
             this.PreprocessorSymbolNames = defineConstants;
+            this.SuppressedDiagnosticIds = suppressedDiagnosticIds;
             this.SourceFiles = sourceFiles;
             this.References = references;
             this.ProjectReferences = projectReferences;
@@ -101,13 +104,6 @@ public static ProjectFileInfo Create(
                 return null;
             }
 
-#if NET46
-            if (PlatformHelper.IsMono)
-            {
-                return CreateForMono(projectFilePath, solutionDirectory, options, logger, diagnostics);
-            }
-#endif
-
             var globalProperties = new Dictionary<string, string>
             {
                 { PropertyNames.DesignTimeBuild, "true" },
@@ -120,6 +116,15 @@ public static ProjectFileInfo Create(
             {
                 globalProperties.Add(PropertyNames.MSBuildExtensionsPath, options.MSBuildExtensionsPath);
             }
+            else
+            {
+                globalProperties.Add(PropertyNames.MSBuildExtensionsPath, AppContext.BaseDirectory);
+            }
+
+            if (PlatformHelper.IsMono)
+            {
+                globalProperties.Add(PropertyNames.TargetFrameworkRootPath, "/Library/Frameworks/Mono.framework/Libraries/mono/xbuild-frameworks");
+            }
 
             if (!string.IsNullOrWhiteSpace(options.VisualStudioVersion))
             {
@@ -128,12 +133,12 @@ public static ProjectFileInfo Create(
 
             var collection = new ProjectCollection(globalProperties);
 
-            logger.LogInformation($"Using toolset {options.ToolsVersion ?? collection.DefaultToolsVersion} for '{projectFilePath}'");
-
             var project = string.IsNullOrEmpty(options.ToolsVersion)
                 ? collection.LoadProject(projectFilePath)
                 : collection.LoadProject(projectFilePath, options.ToolsVersion);
 
+            logger.LogInformation($"Using tools version: {project.ToolsVersion}");
+
             var projectInstance = project.CreateProjectInstance();
             var buildResult = projectInstance.Build(TargetNames.ResolveReferences,
                 new[] { new MSBuildLogForwarder(logger, diagnostics) });
@@ -155,6 +160,7 @@ public static ProjectFileInfo Create(
             var assemblyOriginatorKeyFile = projectInstance.GetPropertyValue(PropertyNames.AssemblyOriginatorKeyFile);
             var documentationFile = projectInstance.GetPropertyValue(PropertyNames.DocumentationFile);
             var defineConstants = PropertyConverter.ToDefineConstants(projectInstance.GetPropertyValue(PropertyNames.DefineConstants));
+            var noWarn = PropertyConverter.ToSuppressDiagnostics(projectInstance.GetPropertyValue(PropertyNames.NoWarn));
 
             var sourceFiles = projectInstance
                 .GetItems(ItemNames.Compile)
@@ -180,8 +186,8 @@ public static ProjectFileInfo Create(
             return new ProjectFileInfo(
                 projectFilePath, assemblyName, name, targetFramework, specifiedLanguageVersion,
                 projectGuid, targetPath, allowUnsafe, outputKind, signAssembly, assemblyOriginatorKeyFile,
-                !string.IsNullOrWhiteSpace(documentationFile), defineConstants, sourceFiles, references,
-                projectReferences, analyzers);
+                !string.IsNullOrWhiteSpace(documentationFile), defineConstants, noWarn,
+                sourceFiles, references, projectReferences, analyzers);
         }
 
         private static bool ReferenceSourceTargetIsProjectReference(ProjectItemInstance projectItem)