Updated annotations based on code review feedback

src/Compilers/Core/MSBuildTask/CommandLineBuilderExtension.cs

@@ -6,6 +6,7 @@
 
 using System;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Text;
 using Microsoft.Build.Framework;
@@ -174,7 +175,7 @@ internal void AppendSwitchWithSplitting(string switchName, string? parameter, st
         /// even if it contains the separators and white space only
         /// Split on the characters provided.
         /// </summary>
-        internal static bool IsParameterEmpty(string parameter, params char[] splitOn)
+        internal static bool IsParameterEmpty([NotNullWhen(false)] string? parameter, params char[] splitOn)
         {
             if (parameter != null)
             {
@@ -202,12 +203,12 @@ internal void AppendSwitchIfNotNull
         (
             string switchName,
             ITaskItem[]? parameters,
-            string[] metadataNames,
+            string[]? metadataNames,
             bool[]? treatAsFlags       // May be null. In this case no metadata are treated as flags.
             )
         {
             Debug.Assert(treatAsFlags == null
-                         || (metadataNames.Length == treatAsFlags.Length),
+                         || (metadataNames?.Length == treatAsFlags.Length),
                          "metadataNames and treatAsFlags should have the same length.");
 
             if (parameters != null)

src/Compilers/Core/MSBuildTaskTests/IntegrationTests.cs

@@ -11,25 +11,20 @@
 using System.Linq;
 using Microsoft.CodeAnalysis.Test.Utilities;
 using Roslyn.Test.Utilities;
-using Roslyn.Utilities;
 using Xunit;
 
 namespace Microsoft.CodeAnalysis.BuildTasks.UnitTests
 {
     public class IntegrationTests : TestBase
     {
-        private static readonly string s_msbuildDirectory;
-        private static readonly string? s_msbuildExecutable;
+        private static readonly string? s_msbuildDirectory;
 
         static IntegrationTests()
         {
             s_msbuildDirectory = DesktopTestHelpers.GetMSBuildDirectory();
-            if (s_msbuildDirectory != null)
-            {
-                s_msbuildExecutable = Path.Combine(s_msbuildDirectory, "MSBuild.exe");
-            }
         }
 
+        private readonly string _msbuildExecutable;
         private readonly TempDirectory _tempDirectory;
         private readonly List<Process> _existingServerList = new List<Process>();
         private readonly string _buildTaskDll;
@@ -41,6 +36,7 @@ public IntegrationTests()
                 throw new InvalidOperationException("Could not locate MSBuild");
             }
 
+            _msbuildExecutable = Path.Combine(s_msbuildDirectory, "MSBuild.exe");
             _tempDirectory = Temp.CreateDirectory();
             _existingServerList = Process.GetProcessesByName(Path.GetFileNameWithoutExtension("VBCSCompiler")).ToList();
             _buildTaskDll = typeof(ManagedCompiler).Assembly.Location;
@@ -409,10 +405,8 @@ End Class
         [Fact(Skip = "https://github.com/dotnet/roslyn/issues/1445")]
         public void SimpleMSBuild()
         {
-            RoslynDebug.Assert(s_msbuildExecutable is object);
-
             string arguments = string.Format(@"/m /nr:false /t:Rebuild /p:UseSharedCompilation=false /p:UseRoslyn=1 HelloSolution.sln");
-            var result = RunCommandLineCompiler(s_msbuildExecutable, arguments, _tempDirectory, SimpleMsBuildFiles);
+            var result = RunCommandLineCompiler(_msbuildExecutable, arguments, _tempDirectory, SimpleMsBuildFiles);
 
             using (var resultFile = GetResultFile(_tempDirectory, @"bin\debug\helloproj.exe"))
             {
@@ -610,10 +604,8 @@ End Class
         [Fact(Skip = "https://github.com/dotnet/roslyn/issues/16301")]
         public void ReportAnalyzerMSBuild()
         {
-            RoslynDebug.Assert(s_msbuildExecutable is object);
-
             string arguments = string.Format(@"/m /nr:false /t:Rebuild /p:UseSharedCompilation=false /p:UseRoslyn=1 HelloSolution.sln");
-            var result = RunCommandLineCompiler(s_msbuildExecutable, arguments, _tempDirectory, ReportAnalyzerMsBuildFiles,
+            var result = RunCommandLineCompiler(_msbuildExecutable, arguments, _tempDirectory, ReportAnalyzerMsBuildFiles,
                 new Dictionary<string, string>
                 { { "MyMSBuildToolsPath", Path.GetDirectoryName(typeof(IntegrationTests).Assembly.Location) } });
 
@@ -624,8 +616,6 @@ public void ReportAnalyzerMSBuild()
         [Fact(Skip = "failing msbuild")]
         public void SolutionWithPunctuation()
         {
-            RoslynDebug.Assert(s_msbuildExecutable is object);
-
             var testDir = _tempDirectory.CreateDirectory(@"SLN;!@(goo)'^1");
             var slnFile = testDir.CreateFile("Console;!@(goo)'^(Application1.sln").WriteAllText(
     @"
@@ -790,7 +780,7 @@ public class Class1
 }
 ");
 
-            var result = RunCommandLineCompiler(s_msbuildExecutable, "/p:UseSharedCompilation=false", testDir.Path);
+            var result = RunCommandLineCompiler(_msbuildExecutable, "/p:UseSharedCompilation=false", testDir.Path);
             Assert.Equal(0, result.ExitCode);
             Assert.Equal("", result.Errors);
         }

src/Test/Utilities/Portable/Platform/Desktop/TestHelpers.cs

-#if NET472
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#nullable enable
+
+#if NET472
+
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
@@ -275,7 +282,7 @@ public override void Initialize(AnalysisContext context)
             return analyzerImage;
         }
 
-        public static string GetMSBuildDirectory()
+        public static string? GetMSBuildDirectory()
         {
             var vsVersion = Environment.GetEnvironmentVariable("VisualStudioVersion") ?? "14.0";
             using (var key = Registry.LocalMachine.OpenSubKey($@"SOFTWARE\Microsoft\MSBuild\ToolsVersions\{vsVersion}", false))