Check for MSBuild version is higher than required by the .NET SDK

src/OmniSharp.Abstractions/Services/DotNetInfo.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Text.RegularExpressions;
 using NuGet.Versioning;
 
 namespace OmniSharp.Services
@@ -16,13 +17,15 @@ public class DotNetInfo
         public string OSPlatform { get; }
         public string RID { get; }
         public string BasePath { get; }
+        public SemanticVersion SdkVersion { get; }
+        public string SdksPath { get; }
 
         private DotNetInfo()
         {
             IsEmpty = true;
         }
 
-        private DotNetInfo(string version, string osName, string osVersion, string osPlatform, string rid, string basePath)
+        private DotNetInfo(string version, string osName, string osVersion, string osPlatform, string rid, string basePath, string sdkVersion, string sdksPath)
         {
             IsEmpty = false;
 
@@ -35,6 +38,11 @@ private DotNetInfo(string version, string osName, string osVersion, string osPla
             OSPlatform = osPlatform;
             RID = rid;
             BasePath = basePath;
+
+            SdkVersion = SemanticVersion.TryParse(sdkVersion, out var sdkValue)
+                ? sdkValue
+                : null;
+            SdksPath = sdksPath;
         }
 
         public static DotNetInfo Parse(List<string> lines)
@@ -50,6 +58,8 @@ public static DotNetInfo Parse(List<string> lines)
             var osPlatform = string.Empty;
             var rid = string.Empty;
             var basePath = string.Empty;
+            var sdkVersion = string.Empty;
+            var sdksPath = string.Empty;
 
             foreach (var line in lines)
             {
@@ -84,19 +94,32 @@ public static DotNetInfo Parse(List<string> lines)
                         basePath = value;
                     }
                 }
+                else if (string.IsNullOrEmpty(sdkVersion))
+                {
+                    var getSdkVersionAndPath = new Regex(@"^\s*(\d+\.\d+\.\d+)\s\[(.*)\]\s*$", RegexOptions.Multiline);
+                    var match = getSdkVersionAndPath.Match(line);
+
+                    if (match.Success)
+                    {
+                        sdkVersion = match.Groups[1].Value;
+                        sdksPath = match.Groups[2].Value;
+                    }
+                }
             }
 
             if (string.IsNullOrWhiteSpace(version) &&
                 string.IsNullOrWhiteSpace(osName) &&
                 string.IsNullOrWhiteSpace(osVersion) &&
                 string.IsNullOrWhiteSpace(osPlatform) &&
                 string.IsNullOrWhiteSpace(rid) &&
-                string.IsNullOrWhiteSpace(basePath))
+                string.IsNullOrWhiteSpace(basePath) &&
+                string.IsNullOrWhiteSpace(sdkVersion) &&
+                string.IsNullOrWhiteSpace(sdksPath))
             {
                 return Empty;
             }
 
-            return new DotNetInfo(version, osName, osVersion, osPlatform, rid, basePath);
+            return new DotNetInfo(version, osName, osVersion, osPlatform, rid, basePath, sdkVersion, sdksPath);
         }
     }
 }

src/OmniSharp.Host/CompositionHostBuilder.cs

@@ -40,7 +40,7 @@ public CompositionHostBuilder(
             _exportDescriptorProviders = exportDescriptorProviders ?? Array.Empty<ExportDescriptorProvider>();
         }
 
-        public CompositionHost Build()
+        public CompositionHost Build(string workingDirectory)
         {
             var options = _serviceProvider.GetRequiredService<IOptionsMonitor<OmniSharpOptions>>();
             var memoryCache = _serviceProvider.GetRequiredService<IMemoryCache>();
@@ -64,7 +64,8 @@ public CompositionHost Build()
             // This is for tests, where the MSBuild instance may be registered early.
             if (msbuildLocator.RegisteredInstance == null)
             {
-                msbuildLocator.RegisterDefaultInstance(logger);
+                var dotNetInfo = dotNetCliService.GetInfo(workingDirectory);
+                msbuildLocator.RegisterDefaultInstance(logger, dotNetInfo);
             }
 
             config = config

src/OmniSharp.Host/MSBuild/Discovery/Extensions.cs

@@ -1,13 +1,20 @@
-using System.IO;
+using System;
+using System.IO;
 using Microsoft.Extensions.Logging;
+using OmniSharp.Services;
 
 namespace OmniSharp.MSBuild.Discovery
 {
     internal static class Extensions
     {
-        public static void RegisterDefaultInstance(this IMSBuildLocator msbuildLocator, ILogger logger)
+        private static readonly Version s_minimumMSBuildVersion = new Version(16, 3);
+
+        public static void RegisterDefaultInstance(this IMSBuildLocator msbuildLocator, ILogger logger, DotNetInfo dotNetInfo = null)
         {
-            var bestInstanceFound = GetBestInstance(msbuildLocator, logger, out var invalidVSFound, out var vsWithoutSdkResolver);
+            var minimumMSBuildVersion = GetSdkMinimumMSBuildVersion(dotNetInfo, logger);
+            logger.LogDebug($".NET SDK requires MSBuild instances version {minimumMSBuildVersion} or higher");
+
+            var bestInstanceFound = GetBestInstance(msbuildLocator, minimumMSBuildVersion, logger, out var invalidVSFound, out var vsWithoutSdkResolver);
 
             if (bestInstanceFound != null)
             {
@@ -16,7 +23,7 @@ public static void RegisterDefaultInstance(this IMSBuildLocator msbuildLocator,
                 if (invalidVSFound && bestInstanceFound.DiscoveryType == DiscoveryType.StandAlone)
                 {
                     logger.LogWarning(
-                        @"It looks like you have Visual Studio lower than VS 2019 16.3 installed.
+                        $@"It looks like you have Visual Studio lower than VS 2019 {s_minimumMSBuildVersion} installed.
  Try updating Visual Studio to the most recent release to enable better MSBuild support."
                     );
                 }
@@ -29,6 +36,31 @@ Try updating Visual Studio 2019 installation with .NET Core SDK to enable better
                     );
                 }
 
+                if (bestInstanceFound.Version < minimumMSBuildVersion)
+                {
+                    if (bestInstanceFound.DiscoveryType == DiscoveryType.Mono)
+                    {
+                        logger.LogWarning(
+                            $@"It looks like you have Mono installed which contains a MSBuild lower than {minimumMSBuildVersion} which is the minimum supported by the configured .NET Core Sdk.
+ Try updating Mono to the latest stable or preview version to enable better .NET Core Sdk support."
+                        );
+                    }
+                    else if (bestInstanceFound.DiscoveryType == DiscoveryType.StandAlone)
+                    {
+                        logger.LogWarning(
+                            $@"It looks like you have Visual Studio 2019 installed which contains a MSBuild lower than {minimumMSBuildVersion} which is the minimum supported by the configured .NET Core Sdk.
+ Try updating Visual Studio to version {minimumMSBuildVersion} or higher to enable better .NET Core Sdk support."
+                        );
+                    }
+                    else if (bestInstanceFound.DiscoveryType == DiscoveryType.UserOverride)
+                    {
+                        logger.LogWarning(
+                            $@"It looks like you have overridden the version of MSBuild with a version lower than {minimumMSBuildVersion} which is the minimum supported by the configured .NET Core Sdk.
+ Try updating your MSBuild to version {minimumMSBuildVersion} or higher to enable better .NET Core Sdk support."
+                        );
+                    }
+                }
+
                 msbuildLocator.RegisterInstance(bestInstanceFound);
             }
             else
@@ -55,12 +87,12 @@ public static bool HasDotNetSdksResolvers(this MSBuildInstance instance)
         /// Checks if it is MSBuild from Visual Studio 2017 RTM that cannot be used.
         /// </summary>
         public static bool IsInvalidVisualStudio(this MSBuildInstance instance)
-            => (instance.Version.Major < 16 ||
-                (instance.Version.Major == 16 && instance.Version.Minor < 3))
+            => (instance.Version.Major < s_minimumMSBuildVersion.Major ||
+                (instance.Version.Major == s_minimumMSBuildVersion.Major && instance.Version.Minor < s_minimumMSBuildVersion.Minor))
                 && (instance.DiscoveryType == DiscoveryType.DeveloperConsole
                     || instance.DiscoveryType == DiscoveryType.VisualStudioSetup);
 
-        public static MSBuildInstance GetBestInstance(this IMSBuildLocator msbuildLocator, ILogger logger, out bool invalidVSFound, out bool vsWithoutSdkResolver)
+        public static MSBuildInstance GetBestInstance(this IMSBuildLocator msbuildLocator, Version minimumMSBuildVersion, ILogger logger, out bool invalidVSFound, out bool vsWithoutSdkResolver)
         {
             invalidVSFound = false;
             vsWithoutSdkResolver = false;
@@ -69,7 +101,7 @@ public static MSBuildInstance GetBestInstance(this IMSBuildLocator msbuildLocato
 
             foreach (var instance in msbuildLocator.GetInstances())
             {
-                var score = GetInstanceFeatureScore(instance);
+                var score = GetInstanceFeatureScore(instance, minimumMSBuildVersion);
 
                 logger.LogDebug($"MSBuild instance {instance.Name} {instance.Version} scored at {score}");
 
@@ -88,7 +120,7 @@ public static MSBuildInstance GetBestInstance(this IMSBuildLocator msbuildLocato
             return bestMatchInstance;
         }
 
-        private static int GetInstanceFeatureScore(MSBuildInstance i)
+        private static int GetInstanceFeatureScore(MSBuildInstance i, Version minimumMSBuildVersion)
         {
             var score = 0;
 
@@ -112,5 +144,28 @@ private static int GetInstanceFeatureScore(MSBuildInstance i)
 
             return score;
         }
+
+        public static Version GetSdkMinimumMSBuildVersion(DotNetInfo dotNetInfo, ILogger logger)
+        {
+            if (dotNetInfo is null
+                || string.IsNullOrWhiteSpace(dotNetInfo.SdksPath)
+                || dotNetInfo.SdkVersion is null)
+            {
+                return s_minimumMSBuildVersion;
+            }
+
+            var version = dotNetInfo.SdkVersion;
+            var sdksPath = dotNetInfo.SdksPath;
+            var minimumVersionPath = Path.Combine(sdksPath, version.ToNormalizedString(), "minimumMSBuildVersion");
+
+            if (!File.Exists(minimumVersionPath))
+            {
+                logger.LogDebug($"Unable to locate minimumMSBuildVersion file at '{minimumVersionPath}'");
+                return s_minimumMSBuildVersion;
+            }
+
+            var minimumVersionText = File.ReadAllText(minimumVersionPath);
+            return Version.Parse(minimumVersionText);
+        }
     }
 }

src/OmniSharp.Http/Startup.cs

@@ -60,7 +60,7 @@ public IServiceProvider ConfigureServices(IServiceCollection services)
             _compositionHost = new CompositionHostBuilder(serviceProvider)
                 .WithOmniSharpAssemblies()
                 .WithAssemblies(assemblyLoader.LoadByAssemblyNameOrPath(logger, plugins).ToArray())
-                .Build();
+                .Build(_environment.TargetDirectory);
 
             return serviceProvider;
         }

src/OmniSharp.LanguageServerProtocol/LanguageServerHost.cs

@@ -56,7 +56,7 @@ public LanguageServerHost(
                 .WithOutput(output)
                 .ConfigureLogging(x => x
                         .AddLanguageProtocolLogging()
-                    // .SetMinimumLevel(application.LogLevel)
+                // .SetMinimumLevel(application.LogLevel)
                 )
                 .OnInitialize(Initialize)
                 .WithServices(ConfigureServices);
@@ -202,7 +202,7 @@ IServiceCollection services
                 .WithAssemblies(typeof(LanguageServerHost).Assembly)
                 .WithAssemblies(assemblyLoader.LoadByAssemblyNameOrPath(logger, plugins.AssemblyNames).ToArray());
 
-            return (serviceProvider, compositionHostBuilder.Build());
+            return (serviceProvider, compositionHostBuilder.Build(environment.TargetDirectory));
         }
 
         internal static RequestHandlers ConfigureCompositionHost(ILanguageServer server,
@@ -241,7 +241,7 @@ internal static RequestHandlers ConfigureCompositionHost(ILanguageServer server,
 
             logger.LogTrace(
                 "Configured Document Selectors {@DocumentSelectors}",
-                documentSelectors.Select(x => new {x.language, x.selector})
+                documentSelectors.Select(x => new { x.language, x.selector })
             );
 
             var omnisharpRequestHandlers =
@@ -365,7 +365,7 @@ private static IDictionary<string, Lazy<LanguageProtocolInteropHandler>> Initial
 
             IDictionary<string, Lazy<LanguageProtocolInteropHandler>> endpointHandlers = null;
             var updateBufferEndpointHandler = new Lazy<LanguageProtocolInteropHandler<UpdateBufferRequest, object>>(
-                () => (LanguageProtocolInteropHandler<UpdateBufferRequest, object>) endpointHandlers[
+                () => (LanguageProtocolInteropHandler<UpdateBufferRequest, object>)endpointHandlers[
                     OmniSharpEndpoints.UpdateBuffer].Value);
             var languagePredicateHandler = new LanguagePredicateHandler(projectSystems);
             var projectSystemPredicateHandler = new StaticLanguagePredicateHandler("Projects");

src/OmniSharp.Stdio/Host.cs

@@ -44,7 +44,7 @@ public Host(
 
             _logger.LogInformation($"Starting OmniSharp on {Platform.Current}");
 
-            _compositionHost = compositionHostBuilder.Build();
+            _compositionHost = compositionHostBuilder.Build(_environment.TargetDirectory);
             _cachedStringBuilder = new CachedStringBuilder();
 
             var handlers = Initialize();

tests/OmniSharp.Http.Tests/EndpointMiddlewareFacts.cs

@@ -121,7 +121,7 @@ private PlugInHost CreatePlugInHost(params Assembly[] assemblies)
             var serviceProvider = TestServiceProvider.Create(this.TestOutput, new OmniSharpEnvironment());
             var compositionHost = new CompositionHostBuilder(serviceProvider)
                 .WithAssemblies(assemblies)
-                .Build();
+                .Build(workingDirectory: null);
 
             return new PlugInHost(serviceProvider, compositionHost);
         }

tests/OmniSharp.MSBuild.Tests/AbstractMSBuildTestFixture.cs

@@ -27,7 +27,7 @@ public AbstractMSBuildTestFixture(ITestOutputHelper output)
 
             // Some tests require MSBuild to be discovered early
             // to ensure that the Microsoft.Build.* assemblies can be located
-            _msbuildLocator.RegisterDefaultInstance(this.LoggerFactory.CreateLogger("MSBuildTests"));
+            _msbuildLocator.RegisterDefaultInstance(this.LoggerFactory.CreateLogger("MSBuildTests"), dotNetInfo: null);
         }
 
         public void Dispose()

tests/OmniSharp.MSBuild.Tests/MSBuildSelectionTests.cs

@@ -33,7 +33,7 @@ public void RegisterDefaultInstanceFindsTheBestInstanceAvailable()
             var logger = LoggerFactory.CreateLogger(nameof(RegisterDefaultInstanceFindsTheBestInstanceAvailable));
 
             // test
-            msbuildLocator.RegisterDefaultInstance(logger);
+            msbuildLocator.RegisterDefaultInstance(logger, dotNetInfo: null);
 
             Assert.NotNull(msbuildLocator.RegisteredInstance);
             Assert.Same(msBuildInstances[1], msbuildLocator.RegisteredInstance);
@@ -72,7 +72,7 @@ public void RegisterDefaultInstanceFindsTheBestInstanceAvailableEvenWithOtherVal
             );
 
             // test
-            msbuildLocator.RegisterDefaultInstance(logger);
+            msbuildLocator.RegisterDefaultInstance(logger, dotNetInfo: null);
 
             Assert.NotNull(msbuildLocator.RegisteredInstance);
             Assert.Same(msBuildInstances[2], msbuildLocator.RegisteredInstance);
@@ -112,7 +112,7 @@ public void RegisterDefaultInstanceFindsTheNewestInstanceAvailableEvenWithOtherV
             );
 
             // test
-            msbuildLocator.RegisterDefaultInstance(logger);
+            msbuildLocator.RegisterDefaultInstance(logger, dotNetInfo: null);
 
             Assert.NotNull(msbuildLocator.RegisteredInstance);
             Assert.Same(msBuildInstances[2], msbuildLocator.RegisteredInstance);
@@ -159,7 +159,7 @@ public void RegisterDefaultInstanceFindsUserOverrideAvailableEvenWithOtherValidI
             );
 
             // test
-            msbuildLocator.RegisterDefaultInstance(logger);
+            msbuildLocator.RegisterDefaultInstance(logger, dotNetInfo: null);
 
             Assert.NotNull(msbuildLocator.RegisteredInstance);
             Assert.Same(msBuildInstances[4], msbuildLocator.RegisteredInstance);
@@ -186,7 +186,7 @@ public void RegisterDefaultInstancePrefersSupportedVSLowerVersionInstanceOverSta
             var logger = LoggerFactory.CreateLogger(nameof(RegisterDefaultInstancePrefersSupportedVSLowerVersionInstanceOverStandAlone));
 
             // test
-            msbuildLocator.RegisterDefaultInstance(logger);
+            msbuildLocator.RegisterDefaultInstance(logger, dotNetInfo: null);
 
             Assert.NotNull(msbuildLocator.RegisteredInstance);
             Assert.Same(msBuildInstances[0], msbuildLocator.RegisteredInstance);
@@ -215,7 +215,7 @@ public void RegisterDefaultInstancePrefersStandAloneOverSupportedVSInstanceWitho
             var logger = LoggerFactory.CreateLogger(nameof(RegisterDefaultInstancePrefersStandAloneOverSupportedVSInstanceWithoutDotnetCore));
 
             // test
-            msbuildLocator.RegisterDefaultInstance(logger);
+            msbuildLocator.RegisterDefaultInstance(logger, dotNetInfo: null);
 
             Assert.NotNull(msbuildLocator.RegisteredInstance);
             Assert.Same(msBuildInstances[1], msbuildLocator.RegisteredInstance);
@@ -246,7 +246,7 @@ public void StandAloneIsPreferredOverUnsupportedVS(string vsVersion)
             var logger = LoggerFactory.CreateLogger(nameof(StandAloneIsPreferredOverUnsupportedVS));
 
             // test
-            msbuildLocator.RegisterDefaultInstance(logger);
+            msbuildLocator.RegisterDefaultInstance(logger, dotNetInfo: null);
 
             Assert.NotNull(msbuildLocator.RegisteredInstance);
             Assert.Same(msBuildInstances[1], msbuildLocator.RegisteredInstance);

tests/TestUtility/OmniSharpTestHost.cs

@@ -88,7 +88,7 @@ public static OmniSharpTestHost Create(
             [CallerMemberName] string callerName = "")
         {
             var compositionHost = new CompositionHostBuilder(serviceProvider, s_lazyAssemblies.Value, additionalExports)
-                .Build();
+                .Build(workingDirectory: null);
 
             WorkspaceInitializer.Initialize(serviceProvider, compositionHost);