Re-architect how MSBuild is loaded by OmniSharp

build.cake

@@ -245,60 +245,102 @@ Task("CreateMSBuildFolder")
 {
     DirectoryHelper.ForceCreate(env.Folders.MSBuild);
 
+    var msbuild15TargetFolder = CombinePaths(env.Folders.MSBuild, "15.0");
+    var msbuild15BinTargetFolder = CombinePaths(msbuild15TargetFolder, "Bin");
+
+    var msbuildLibraries = new []
+    {
+        "Microsoft.Build",
+        "Microsoft.Build.Framework",
+        "Microsoft.Build.Tasks.Core",
+        "Microsoft.Build.Utilities.Core"
+    };
+
     string sdkResolverTFM;
 
     if (Platform.Current.IsWindows)
     {
         Information("Copying MSBuild runtime...");
-        var msbuildRuntimeFolder = CombinePaths(env.Folders.Tools, "Microsoft.Build.Runtime", "contentFiles", "any", "net46");
-        DirectoryHelper.Copy(msbuildRuntimeFolder, env.Folders.MSBuild);
+
+        var msbuildSourceFolder = CombinePaths(env.Folders.Tools, "Microsoft.Build.Runtime", "contentFiles", "any", "net46");
+        DirectoryHelper.Copy(msbuildSourceFolder, msbuild15BinTargetFolder, copySubDirectories: false);
+
+        var msbuild15SourceFolder = CombinePaths(msbuildSourceFolder, "15.0");
+        DirectoryHelper.Copy(msbuild15SourceFolder, msbuild15TargetFolder);
+
+        Information("Copying MSBuild libraries...");
+
+        foreach (var library in msbuildLibraries)
+        {
+            var libraryFileName = library + ".dll";
+            var librarySourcePath = CombinePaths(env.Folders.Tools, library, "lib", "net46", libraryFileName);
+            var libraryTargetPath = CombinePaths(msbuild15BinTargetFolder, libraryFileName);
+            FileHelper.Copy(librarySourcePath, libraryTargetPath);
+        }
+
         sdkResolverTFM = "net46";
     }
     else
     {
         Information("Copying Mono MSBuild runtime...");
-        DirectoryHelper.Copy(env.Folders.MonoMSBuildRuntime, env.Folders.MSBuild);
+
+        var msbuildSourceFolder = env.Folders.MonoMSBuildRuntime;
+        DirectoryHelper.Copy(msbuildSourceFolder, msbuild15BinTargetFolder, copySubDirectories: false);
+
+        var msbuild15SourceFolder = CombinePaths(msbuildSourceFolder, "15.0");
+        DirectoryHelper.Copy(msbuild15SourceFolder, msbuild15TargetFolder);
+
+        Information("Copying MSBuild libraries...");
+
+        foreach (var library in msbuildLibraries)
+        {
+            var libraryFileName = library + ".dll";
+            var librarySourcePath = CombinePaths(env.Folders.MonoMSBuildLib, libraryFileName);
+            var libraryTargetPath = CombinePaths(msbuild15BinTargetFolder, libraryFileName);
+            FileHelper.Copy(librarySourcePath, libraryTargetPath);
+        }
+
         sdkResolverTFM = "netstandard1.5";
     }
 
     // Copy MSBuild SDK Resolver and DotNetHostResolver
     Information("Coping MSBuild SDK resolver...");
-    var sdkResolverFolder = CombinePaths(env.Folders.Tools, "Microsoft.DotNet.MSBuildSdkResolver", "lib", sdkResolverTFM);
-    var msbuildSdkResolverFolder = CombinePaths(env.Folders.MSBuild, "SdkResolvers", "Microsoft.DotNet.MSBuildSdkResolver");
-    DirectoryHelper.ForceCreate(msbuildSdkResolverFolder);
+    var sdkResolverSourceFolder = CombinePaths(env.Folders.Tools, "Microsoft.DotNet.MSBuildSdkResolver", "lib", sdkResolverTFM);
+    var sdkResolverTargetFolder = CombinePaths(msbuild15BinTargetFolder, "SdkResolvers", "Microsoft.DotNet.MSBuildSdkResolver");
+    DirectoryHelper.ForceCreate(sdkResolverTargetFolder);
     FileHelper.Copy(
-        source: CombinePaths(sdkResolverFolder, "Microsoft.DotNet.MSBuildSdkResolver.dll"),
-        destination: CombinePaths(msbuildSdkResolverFolder, "Microsoft.DotNet.MSBuildSdkResolver.dll"));
+        source: CombinePaths(sdkResolverSourceFolder, "Microsoft.DotNet.MSBuildSdkResolver.dll"),
+        destination: CombinePaths(sdkResolverTargetFolder, "Microsoft.DotNet.MSBuildSdkResolver.dll"));
 
     if (Platform.Current.IsWindows)
     {
-        CopyDotNetHostResolver(env, "win", "x86", "hostfxr.dll", msbuildSdkResolverFolder, copyToArchSpecificFolder: true);
-        CopyDotNetHostResolver(env, "win", "x64", "hostfxr.dll", msbuildSdkResolverFolder, copyToArchSpecificFolder: true);
+        CopyDotNetHostResolver(env, "win", "x86", "hostfxr.dll", sdkResolverTargetFolder, copyToArchSpecificFolder: true);
+        CopyDotNetHostResolver(env, "win", "x64", "hostfxr.dll", sdkResolverTargetFolder, copyToArchSpecificFolder: true);
     }
     else if (Platform.Current.IsMacOS)
     {
-        CopyDotNetHostResolver(env, "osx", "x64", "libhostfxr.dylib", msbuildSdkResolverFolder, copyToArchSpecificFolder: false);
+        CopyDotNetHostResolver(env, "osx", "x64", "libhostfxr.dylib", sdkResolverTargetFolder, copyToArchSpecificFolder: false);
     }
     else if (Platform.Current.IsLinux)
     {
-        CopyDotNetHostResolver(env, "linux", "x64", "libhostfxr.so", msbuildSdkResolverFolder, copyToArchSpecificFolder: false);
+        CopyDotNetHostResolver(env, "linux", "x64", "libhostfxr.so", sdkResolverTargetFolder, copyToArchSpecificFolder: false);
     }
 
     // Copy content of Microsoft.Net.Compilers
     Information("Copying Microsoft.Net.Compilers...");
-    var compilersFolder = CombinePaths(env.Folders.Tools, "Microsoft.Net.Compilers", "tools");
-    var msbuildRoslynFolder = CombinePaths(env.Folders.MSBuild, "Roslyn");
+    var compilersSourceFolder = CombinePaths(env.Folders.Tools, "Microsoft.Net.Compilers", "tools");
+    var compilersTargetFolder = CombinePaths(msbuild15BinTargetFolder, "Roslyn");
 
-    DirectoryHelper.Copy(compilersFolder, msbuildRoslynFolder);
+    DirectoryHelper.Copy(compilersSourceFolder, compilersTargetFolder);
 
     // Delete unnecessary files
-    FileHelper.Delete(CombinePaths(msbuildRoslynFolder, "Microsoft.CodeAnalysis.VisualBasic.dll"));
-    FileHelper.Delete(CombinePaths(msbuildRoslynFolder, "Microsoft.VisualBasic.Core.targets"));
-    FileHelper.Delete(CombinePaths(msbuildRoslynFolder, "VBCSCompiler.exe"));
-    FileHelper.Delete(CombinePaths(msbuildRoslynFolder, "VBCSCompiler.exe.config"));
-    FileHelper.Delete(CombinePaths(msbuildRoslynFolder, "vbc.exe"));
-    FileHelper.Delete(CombinePaths(msbuildRoslynFolder, "vbc.exe.config"));
-    FileHelper.Delete(CombinePaths(msbuildRoslynFolder, "vbc.rsp"));
+    FileHelper.Delete(CombinePaths(compilersTargetFolder, "Microsoft.CodeAnalysis.VisualBasic.dll"));
+    FileHelper.Delete(CombinePaths(compilersTargetFolder, "Microsoft.VisualBasic.Core.targets"));
+    FileHelper.Delete(CombinePaths(compilersTargetFolder, "VBCSCompiler.exe"));
+    FileHelper.Delete(CombinePaths(compilersTargetFolder, "VBCSCompiler.exe.config"));
+    FileHelper.Delete(CombinePaths(compilersTargetFolder, "vbc.exe"));
+    FileHelper.Delete(CombinePaths(compilersTargetFolder, "vbc.exe.config"));
+    FileHelper.Delete(CombinePaths(compilersTargetFolder, "vbc.rsp"));
 });
 
 /// <summary>
@@ -514,7 +556,6 @@ void CopyMonoBuild(BuildEnvironment env, string sourceFolder, string outputFolde
 
     // Copy MSBuild runtime and libraries
     DirectoryHelper.Copy($"{env.Folders.MSBuild}", CombinePaths(outputFolder, "msbuild"));
-    DirectoryHelper.Copy($"{env.Folders.MonoMSBuildLib}", outputFolder);
 
     // Included in Mono
     FileHelper.Delete(CombinePaths(outputFolder, "System.AppContext.dll"));

build/Packages.props

@@ -37,11 +37,14 @@
     <MicrosoftExtensionsPlatformAbstractionsVersion>1.1.0</MicrosoftExtensionsPlatformAbstractionsVersion>
     <MicrosoftNetTestSdkVersion>15.0.0</MicrosoftNetTestSdkVersion>
     <MicrosoftTestPlatformTranslationLayerVersion>15.3.0</MicrosoftTestPlatformTranslationLayerVersion>
+    <MicrosoftVisualStudioSetupConfigurationInteropVersion>1.14.114</MicrosoftVisualStudioSetupConfigurationInteropVersion>
+    <MicrosoftVisualStudioSDKEmbedInteropTypesVersion>15.0.12</MicrosoftVisualStudioSDKEmbedInteropTypesVersion>
     <NewtonsoftJsonVersion>9.0.1</NewtonsoftJsonVersion>
     <NuGetPackagingVersion>4.3.0</NuGetPackagingVersion>
     <NuGetPackagingCoreVersion>4.3.0</NuGetPackagingCoreVersion>
     <NuGetProjectModelVersion>4.3.0</NuGetProjectModelVersion>
     <NuGetVersioningVersion>4.3.0</NuGetVersioningVersion>
+    <SystemCollectionsImmutableVersion>1.4.0</SystemCollectionsImmutableVersion>
     <SystemCompositionVersion>1.0.31</SystemCompositionVersion>
     <SystemReflectionMetadataVersion>1.4.2</SystemReflectionMetadataVersion>
     <SystemThreadingTasksDataflowVersion>4.6.0</SystemThreadingTasksDataflowVersion>

scripts/runhelpers.cake

@@ -249,6 +249,32 @@ private void KillProcessTree(Process process)
     }
     else
     {
-        process.Kill();
+        foreach (var pid in GetUnixChildProcessIds(process.Id))
+        {
+            Run("kill", pid.ToString());
+        }
+
+        Run("kill", process.Id.ToString());
     }
 }
+
+int[] GetUnixChildProcessIds(int processId)
+{
+    var output = RunAndCaptureOutput("ps", "-A -o ppid,pid");
+    var lines = output.Split(new[] { System.Environment.NewLine }, System.StringSplitOptions.RemoveEmptyEntries);
+    var childPIDs = new List<int>();
+
+    foreach (var line in lines)
+    {
+        var pairs = line.Trim().Split(new[] { ' ' }, System.StringSplitOptions.RemoveEmptyEntries);
+
+        int ppid;
+        if (int.TryParse(pairs[0].Trim(), out ppid) && ppid == processId)
+        {
+            childPIDs.Add(int.Parse(pairs[1].Trim()));
+        }
+
+    }
+
+    return childPIDs.ToArray();
+}

src/OmniSharp.Abstractions/Logging/LoggerExtensions.cs

@@ -4,6 +4,11 @@ namespace Microsoft.Extensions.Logging
 {
     public static class LoggerExceptions
     {
+        public static void LogDebug(this ILogger logger, Exception ex, string message, params object[] args)
+        {
+            logger.LogDebug(0, ex, message, args);
+        }
+
         public static void LogError(this ILogger logger, Exception ex, string message, params object[] args)
         {
             logger.LogError(0, ex, message, args);

src/OmniSharp.Abstractions/MSBuild/Discovery/DiscoveryType.cs

@@ -0,0 +1,10 @@
+namespace OmniSharp.MSBuild.Discovery
+{
+    public enum DiscoveryType
+    {
+        StandAlone = 0,
+        DeveloperConsole = 1,
+        VisualStudioSetup = 2,
+        Mono = 3
+    }
+}

src/OmniSharp.Abstractions/MSBuild/Discovery/IMSBuildLocator.cs

@@ -0,0 +1,12 @@
+using System.Collections.Immutable;
+
+namespace OmniSharp.MSBuild.Discovery
+{
+    public interface IMSBuildLocator
+    {
+        MSBuildInstance RegisteredInstance { get; }
+
+        void RegisterInstance(MSBuildInstance instance);
+        ImmutableArray<MSBuildInstance> GetInstances();
+    }
+}

src/OmniSharp.Abstractions/MSBuild/Discovery/MSBuildInstance.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Immutable;
+
+namespace OmniSharp.MSBuild.Discovery
+{
+    public class MSBuildInstance
+    {
+        public string Name { get; }
+        public string MSBuildPath { get; }
+        public Version Version { get; }
+        public DiscoveryType DiscoveryType { get; }
+        public ImmutableDictionary<string, string> PropertyOverrides { get; }
+        public bool SetMSBuildExePathVariable { get; }
+
+        public MSBuildInstance(
+            string name, string msbuildPath, Version version, DiscoveryType discoveryType,
+            ImmutableDictionary<string, string> propertyOverrides = null,
+            bool setMSBuildExePathVariable = false)
+        {
+            Name = name;
+            MSBuildPath = msbuildPath;
+            Version = version ?? new Version(0, 0);
+            DiscoveryType = discoveryType;
+            PropertyOverrides = propertyOverrides ?? ImmutableDictionary<string, string>.Empty;
+            SetMSBuildExePathVariable = setMSBuildExePathVariable;
+        }
+
+        public override string ToString()
+            => $"{Name} {Version} - \"{MSBuildPath}\"";
+    }
+}

src/OmniSharp.Abstractions/OmniSharp.Abstractions.csproj

@@ -15,6 +15,7 @@
     <PackageReference Include="Microsoft.Extensions.PlatformAbstractions" Version="$(MicrosoftExtensionsPlatformAbstractionsVersion)" />
     <PackageReference Include="Newtonsoft.Json" Version="$(NewtonsoftJsonVersion)" />
     <PackageReference Include="NuGet.Versioning" Version="$(NuGetVersioningVersion)" />
+    <PackageReference Include="System.Collections.Immutable" Version="$(SystemCollectionsImmutableVersion)" />
     <PackageReference Include="System.Composition" Version="$(SystemCompositionVersion)" />
     <PackageReference Include="System.ValueTuple" Version="$(SystemValueTupleVersion)" />
   </ItemGroup>

src/OmniSharp.Abstractions/Utilities/PlatformHelper.cs

@@ -60,6 +60,32 @@ private static string RealPath(string path)
             return result;
         }
 
+        public static Version GetMonoVersion()
+        {
+            var output = ProcessHelper.RunAndCaptureOutput("mono", "--version");
+            if (output == null)
+            {
+                return null;
+            }
+
+            // The mono --version text contains several lines. We'll just walk through the first line,
+            // word by word, until we find a word that parses as a version number. Normally, this should
+            // be the *fifth* word. E.g. "Mono JIT compiler version 4.8.0"
+
+            var lines = output.Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
+            var words = lines[0].Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
+
+            foreach (var word in words)
+            {
+                if (Version.TryParse(word, out var version))
+                {
+                    return version;
+                }
+            }
+
+            return null;
+        }
+
         public static string GetMonoRuntimePath()
         {
             if (IsWindows)

src/OmniSharp.Host/AssemblyInfo.cs

@@ -1,3 +1,4 @@
 using System.Runtime.CompilerServices;
 
-[assembly: InternalsVisibleTo("TestUtility")]
+[assembly: InternalsVisibleTo("OmniSharp.Http.Tests")]
+[assembly: InternalsVisibleTo("TestUtility")]

src/OmniSharp.Host/CompositionHostBuilder.cs

@@ -12,6 +12,7 @@
 using OmniSharp.Eventing;
 using OmniSharp.FileWatching;
 using OmniSharp.Mef;
+using OmniSharp.MSBuild.Discovery;
 using OmniSharp.Options;
 using OmniSharp.Roslyn;
 using OmniSharp.Services;
@@ -49,15 +50,24 @@ public CompositionHost Build()
             var assemblyLoader = _serviceProvider.GetRequiredService<IAssemblyLoader>();
             var config = new ContainerConfiguration();
 
-            var assemblies = _assemblies
-                .Concat(new[] { typeof(OmniSharpWorkspace).GetTypeInfo().Assembly, typeof(IRequest).GetTypeInfo().Assembly })
-                .Distinct();
-
-            config = config.WithAssemblies(assemblies);
-
             var fileSystemWatcher = new ManualFileSystemWatcher();
             var metadataHelper = new MetadataHelper(assemblyLoader);
 
+            // We must register an MSBuild instance before composing MEF to ensure that
+            // our AssemblyResolve event is hooked up first.
+            var msbuildLocator = _serviceProvider.GetRequiredService<IMSBuildLocator>();
+            var instances = msbuildLocator.GetInstances();
+            var instance = instances.FirstOrDefault();
+            if (instance != null)
+            {
+                msbuildLocator.RegisterInstance(instance);
+            }
+            else
+            {
+                var logger = loggerFactory.CreateLogger<CompositionHostBuilder>();
+                logger.LogError("Could not locate MSBuild instance to register with OmniSharp");
+            }
+
             config = config
                 .WithProvider(MefValueProvider.From(_serviceProvider))
                 .WithProvider(MefValueProvider.From<IFileSystemWatcher>(fileSystemWatcher))
@@ -69,11 +79,32 @@ public CompositionHost Build()
                 .WithProvider(MefValueProvider.From(options.CurrentValue.FormattingOptions))
                 .WithProvider(MefValueProvider.From(assemblyLoader))
                 .WithProvider(MefValueProvider.From(metadataHelper))
+                .WithProvider(MefValueProvider.From(msbuildLocator))
                 .WithProvider(MefValueProvider.From(_eventEmitter ?? NullEventEmitter.Instance));
 
+            var parts = _assemblies
+                .Concat(new[] { typeof(OmniSharpWorkspace).GetTypeInfo().Assembly, typeof(IRequest).GetTypeInfo().Assembly })
+                .Distinct()
+                .SelectMany(a => SafeGetTypes(a))
+                .ToArray();
+
+            config = config.WithParts(parts);
+
             return config.CreateContainer();
         }
 
+        private static IEnumerable<Type> SafeGetTypes(Assembly a)
+        {
+            try
+            {
+                return a.DefinedTypes.Select(t => t.AsType()).ToArray();
+            }
+            catch (ReflectionTypeLoadException e)
+            {
+                return e.Types.Where(t => t != null).ToArray();
+            }
+        }
+
         public static IServiceProvider CreateDefaultServiceProvider(IConfiguration configuration, IServiceCollection services = null)
         {
             services = services ?? new ServiceCollection();
@@ -83,6 +114,12 @@ public static IServiceProvider CreateDefaultServiceProvider(IConfiguration confi
             services.AddSingleton<IAssemblyLoader, AssemblyLoader>();
             services.AddOptions();
 
+            // MSBuild
+            services.AddSingleton<IMSBuildLocator>(sp =>
+                MSBuildLocator.CreateDefault(
+                    loggerFactory: sp.GetService<ILoggerFactory>(),
+                    assemblyLoader: sp.GetService<IAssemblyLoader>()));
+
             // Setup the options from configuration
             services.Configure<OmniSharpOptions>(configuration);
             services.AddLogging();