Initial attempt at removing explicit #nullable enable in source

src/Cli/Microsoft.DotNet.Cli.Utils/BlockingMemoryStream.cs

@@ -29,7 +29,7 @@ public override int Read(byte[] buffer, int offset, int count)
 
             if (_remaining.Count == 0)
             {
-                byte[] tmp;
+                byte[]? tmp;
                 if (!_buffers.TryTake(out tmp, Timeout.Infinite) || tmp.Length == 0)
                 {
                     return 0;
@@ -40,13 +40,13 @@ public override int Read(byte[] buffer, int offset, int count)
             if (_remaining.Count <= count)
             {
                 count = _remaining.Count;
-                Buffer.BlockCopy(_remaining.Array, _remaining.Offset, buffer, offset, count);
-                _remaining = default(ArraySegment<byte>);
+                Buffer.BlockCopy(_remaining.Array!, _remaining.Offset, buffer, offset, count);
+                _remaining = default;
             }
             else
             {
-                Buffer.BlockCopy(_remaining.Array, _remaining.Offset, buffer, offset, count);
-                _remaining = new ArraySegment<byte>(_remaining.Array, _remaining.Offset + count, _remaining.Count - count);
+                Buffer.BlockCopy(_remaining.Array!, _remaining.Offset, buffer, offset, count);
+                _remaining = new ArraySegment<byte>(_remaining.Array!, _remaining.Offset + count, _remaining.Count - count);
             }
             return count;
         }

src/Cli/Microsoft.DotNet.Cli.Utils/BuiltInCommand.cs

@@ -15,7 +15,7 @@ public class BuiltInCommand : ICommand
         private readonly IBuiltInCommandEnvironment _environment;
         private readonly StreamForwarder _stdOut;
         private readonly StreamForwarder _stdErr;
-        private string _workingDirectory;
+        private string? _workingDirectory;
 
         public string CommandName { get; }
         public string CommandArgs => string.Join(" ", _commandArgs);
@@ -57,7 +57,7 @@ public CommandResult Execute()
 
                     if (!string.IsNullOrEmpty(_workingDirectory))
                     {
-                        _environment.SetWorkingDirectory(_workingDirectory);
+                        _environment.SetWorkingDirectory(_workingDirectory!);
                     }
 
                     var taskOut = _stdOut.BeginRead(new StreamReader(outStream));
@@ -163,17 +163,17 @@ public ICommand CaptureStdOut()
             return this;
         }
 
-        public ICommand EnvironmentVariable(string name, string value)
+        public ICommand EnvironmentVariable(string name, string? value)
         {
             throw new NotImplementedException();
         }
 
-        public ICommand ForwardStdErr(TextWriter to = null, bool onlyIfVerbose = false, bool ansiPassThrough = true)
+        public ICommand ForwardStdErr(TextWriter? to = null, bool onlyIfVerbose = false, bool ansiPassThrough = true)
         {
             throw new NotImplementedException();
         }
 
-        public ICommand ForwardStdOut(TextWriter to = null, bool onlyIfVerbose = false, bool ansiPassThrough = true)
+        public ICommand ForwardStdOut(TextWriter? to = null, bool onlyIfVerbose = false, bool ansiPassThrough = true)
         {
             throw new NotImplementedException();
         }

src/Cli/Microsoft.DotNet.Cli.Utils/Command.cs

@@ -10,15 +10,15 @@ public class Command : ICommand
     {
         private readonly Process _process;
 
-        private StreamForwarder _stdOut;
+        private StreamForwarder? _stdOut;
 
-        private StreamForwarder _stdErr;
+        private StreamForwarder? _stdErr;
 
         private bool _running = false;
 
         private bool _trimTrailingNewlines = false;
 
-        public Command(Process process, bool trimtrailingNewlines = false)
+        public Command(Process? process, bool trimtrailingNewlines = false)
         {
             _trimTrailingNewlines = trimtrailingNewlines;
             _process = process ?? throw new ArgumentNullException(nameof(process));
@@ -28,7 +28,7 @@ public CommandResult Execute()
         {
             return Execute(null);
         }
-        public CommandResult Execute(Action<Process> processStarted)
+        public CommandResult Execute(Action<Process>? processStarted)
         {
             Reporter.Verbose.WriteLine(string.Format(
                 LocalizableStrings.RunningFileNameArguments,
@@ -98,7 +98,7 @@ public ICommand WorkingDirectory(string projectDirectory)
             return this;
         }
 
-        public ICommand EnvironmentVariable(string name, string value)
+        public ICommand EnvironmentVariable(string name, string? value)
         {
             _process.StartInfo.Environment[name] = value;
             return this;
@@ -108,19 +108,19 @@ public ICommand CaptureStdOut()
         {
             ThrowIfRunning();
             EnsureStdOut();
-            _stdOut.Capture(_trimTrailingNewlines);
+            _stdOut?.Capture(_trimTrailingNewlines);
             return this;
         }
 
         public ICommand CaptureStdErr()
         {
             ThrowIfRunning();
             EnsureStdErr();
-            _stdErr.Capture(_trimTrailingNewlines);
+            _stdErr?.Capture(_trimTrailingNewlines);
             return this;
         }
 
-        public ICommand ForwardStdOut(TextWriter to = null, bool onlyIfVerbose = false, bool ansiPassThrough = true)
+        public ICommand ForwardStdOut(TextWriter? to = null, bool onlyIfVerbose = false, bool ansiPassThrough = true)
         {
             ThrowIfRunning();
             if (!onlyIfVerbose || CommandLoggingContext.IsVerbose)
@@ -129,18 +129,18 @@ public ICommand ForwardStdOut(TextWriter to = null, bool onlyIfVerbose = false,
 
                 if (to == null)
                 {
-                    _stdOut.ForwardTo(writeLine: Reporter.Output.WriteLine);
+                    _stdOut?.ForwardTo(writeLine: Reporter.Output.WriteLine);
                     EnvironmentVariable(CommandLoggingContext.Variables.AnsiPassThru, ansiPassThrough.ToString());
                 }
                 else
                 {
-                    _stdOut.ForwardTo(writeLine: to.WriteLine);
+                    _stdOut?.ForwardTo(writeLine: to.WriteLine);
                 }
             }
             return this;
         }
 
-        public ICommand ForwardStdErr(TextWriter to = null, bool onlyIfVerbose = false, bool ansiPassThrough = true)
+        public ICommand ForwardStdErr(TextWriter? to = null, bool onlyIfVerbose = false, bool ansiPassThrough = true)
         {
             ThrowIfRunning();
             if (!onlyIfVerbose || CommandLoggingContext.IsVerbose)
@@ -149,12 +149,12 @@ public ICommand ForwardStdErr(TextWriter to = null, bool onlyIfVerbose = false,
 
                 if (to == null)
                 {
-                    _stdErr.ForwardTo(writeLine: Reporter.Error.WriteLine);
+                    _stdErr?.ForwardTo(writeLine: Reporter.Error.WriteLine);
                     EnvironmentVariable(CommandLoggingContext.Variables.AnsiPassThru, ansiPassThrough.ToString());
                 }
                 else
                 {
-                    _stdErr.ForwardTo(writeLine: to.WriteLine);
+                    _stdErr?.ForwardTo(writeLine: to.WriteLine);
                 }
             }
             return this;
@@ -165,7 +165,7 @@ public ICommand OnOutputLine(Action<string> handler)
             ThrowIfRunning();
             EnsureStdOut();
 
-            _stdOut.ForwardTo(writeLine: handler);
+            _stdOut?.ForwardTo(writeLine: handler);
             return this;
         }
 
@@ -174,7 +174,7 @@ public ICommand OnErrorLine(Action<string> handler)
             ThrowIfRunning();
             EnsureStdErr();
 
-            _stdErr.ForwardTo(writeLine: handler);
+            _stdErr?.ForwardTo(writeLine: handler);
             return this;
         }
 
@@ -210,7 +210,7 @@ private void EnsureStdErr()
             _process.StartInfo.RedirectStandardError = true;
         }
 
-        private void ThrowIfRunning([CallerMemberName] string memberName = null)
+        private void ThrowIfRunning([CallerMemberName] string? memberName = null)
         {
             if (_running)
             {

src/Cli/Microsoft.DotNet.Cli.Utils/CommandResult.cs

@@ -11,10 +11,10 @@ public struct CommandResult
 
         public ProcessStartInfo StartInfo { get; }
         public int ExitCode { get; }
-        public string StdOut { get; }
-        public string StdErr { get; }
+        public string? StdOut { get; }
+        public string? StdErr { get; }
 
-        public CommandResult(ProcessStartInfo startInfo, int exitCode, string stdOut, string stdErr)
+        public CommandResult(ProcessStartInfo startInfo, int exitCode, string? stdOut, string? stdErr)
         {
             StartInfo = startInfo;
             ExitCode = exitCode;

src/Cli/Microsoft.DotNet.Cli.Utils/DangerousFileDetector.cs

@@ -26,7 +26,7 @@ private static class InternetSecurity
             private const uint ZoneInternet = 3;
             private const uint ZoneUntrusted = 4;
             private const int REGDB_E_CLASSNOTREG = unchecked((int)0x80040154);
-            private static IInternetSecurityManager internetSecurityManager = null;
+            private static IInternetSecurityManager? internetSecurityManager = null;
 
 #if NETCOREAPP
             [SupportedOSPlatform("windows")]
@@ -38,11 +38,11 @@ public static bool IsDangerous(string filename)
                     // First check the zone, if they are not an untrusted zone, they aren't dangerous
                     if (internetSecurityManager == null)
                     {
-                        Type iismType = Type.GetTypeFromCLSID(new Guid(CLSID_InternetSecurityManager));
-                        internetSecurityManager = (IInternetSecurityManager)Activator.CreateInstance(iismType);
+                        Type iismType = Type.GetTypeFromCLSID(new Guid(CLSID_InternetSecurityManager))!;
+                        internetSecurityManager = Activator.CreateInstance(iismType!) as IInternetSecurityManager;
                     }
                     int zone = 0;
-                    internetSecurityManager.MapUrlToZone(Path.GetFullPath(filename), out zone, 0);
+                    internetSecurityManager?.MapUrlToZone(Path.GetFullPath(filename), out zone, 0);
                     if (zone < ZoneInternet)
                     {
                         return false;

src/Cli/Microsoft.DotNet.Cli.Utils/DependencyProvider.cs

@@ -72,7 +72,7 @@ public sealed class DependencyProvider
         /// <summary>
         /// The product code of the MSI associated with the dependency provider.
         /// </summary>
-        public string ProductCode => GetProductCode();
+        public string? ProductCode => GetProductCode();
 
         /// <summary>
         /// The path of the provider key, relative to the <see cref="BaseKey"/>.
@@ -143,12 +143,12 @@ public void RemoveDependent(string dependent, bool removeProvider)
                 throw new ArgumentException($"{nameof(dependent)} cannot be empty.");
             }
 
-            using RegistryKey dependentsKey = BaseKey.OpenSubKey(DependentsKeyPath, writable: true);
+            using RegistryKey? dependentsKey = BaseKey.OpenSubKey(DependentsKeyPath, writable: true);
             dependentsKey?.DeleteSubKeyTree(dependent);
 
             if ((removeProvider) && (Dependents.Count() == 0))
             {
-                using RegistryKey providerKey = BaseKey.OpenSubKey(DependenciesKeyRelativePath, writable: true);
+                using RegistryKey? providerKey = BaseKey.OpenSubKey(DependenciesKeyRelativePath, writable: true);
                 providerKey?.DeleteSubKeyTree(ProviderKeyName);
             }
         }
@@ -159,7 +159,7 @@ public void RemoveDependent(string dependent, bool removeProvider)
         /// <returns>All dependents of the provider key.</returns>
         private IEnumerable<string> GetDependents()
         {
-            using RegistryKey dependentsKey = BaseKey.OpenSubKey(DependentsKeyPath);
+            using RegistryKey? dependentsKey = BaseKey.OpenSubKey(DependentsKeyPath);
 
             return dependentsKey?.GetSubKeyNames() ?? Enumerable.Empty<string>();
         }
@@ -169,22 +169,22 @@ private IEnumerable<string> GetDependents()
         /// value.
         /// </summary>
         /// <returns>The ProductCode associated with this dependency provider or <see langword="null"/> if it does not exist.</returns>
-        private string GetProductCode()
+        private string? GetProductCode()
         {
-            using RegistryKey providerKey = BaseKey.OpenSubKey(ProviderKeyPath);
+            using RegistryKey? providerKey = BaseKey.OpenSubKey(ProviderKeyPath);
             return providerKey?.GetValue(null) as string ?? null;
         }
 
         public override string ToString() => ProviderKeyName;
 
-        public static DependencyProvider GetFromProductCode(string productCode, bool allUsers = true)
+        public static DependencyProvider? GetFromProductCode(string productCode, bool allUsers = true)
         {
             var baseKey = allUsers ? Registry.LocalMachine : Registry.CurrentUser;
-            using RegistryKey dependenciesKey = baseKey.OpenSubKey(DependenciesKeyRelativePath);
+            using RegistryKey? dependenciesKey = baseKey.OpenSubKey(DependenciesKeyRelativePath);
 
-            foreach (var providerKeyName in dependenciesKey.GetSubKeyNames())
+            foreach (var providerKeyName in dependenciesKey!.GetSubKeyNames())
             {
-                using RegistryKey providerKey = dependenciesKey.OpenSubKey(providerKeyName);
+                using RegistryKey? providerKey = dependenciesKey.OpenSubKey(providerKeyName);
                 var thisProductCode = providerKey?.GetValue(null) as string ?? null;
                 if (string.Equals(thisProductCode, productCode, StringComparison.OrdinalIgnoreCase))
                 {

src/Cli/Microsoft.DotNet.Cli.Utils/DotDefaultPathCorrector.cs

@@ -15,25 +15,22 @@ public static class DotDefaultPathCorrector
         public static void Correct()
         {
             var pathEditor = new WindowsRegistryEnvironmentPathEditor();
-            var dotDefaultPath =
-                pathEditor.Get(
-                    SdkEnvironmentVariableTarget.DotDefault);
+            var dotDefaultPath = pathEditor.Get(SdkEnvironmentVariableTarget.DotDefault);
             if (NeedCorrection(dotDefaultPath, out var correctedPath))
             {
-                pathEditor.Set(correctedPath,
-                    SdkEnvironmentVariableTarget.DotDefault);
+                pathEditor.Set(correctedPath, SdkEnvironmentVariableTarget.DotDefault);
             }
         }
 
-        internal static bool NeedCorrection(string existingPath, out string correctedPath)
+        internal static bool NeedCorrection(string? existingPath, out string correctedPath)
         {
             correctedPath = string.Empty;
             if (string.IsNullOrWhiteSpace(existingPath))
             {
                 return false;
             }
 
-            IEnumerable<string> paths = existingPath.Split(new char[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
+            IEnumerable<string> paths = existingPath!.Split(new char[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
 
             var inCorrectToolsPaths =
                 paths.Where(p => p.EndsWith(DotnetToolsSuffix, StringComparison.OrdinalIgnoreCase));

src/Cli/Microsoft.DotNet.Cli.Utils/DotnetVersionFile.cs

@@ -7,13 +7,13 @@ internal class DotnetVersionFile
     {
         public bool Exists { get; init; }
 
-        public string CommitSha { get; init; }
+        public string? CommitSha { get; init; }
 
-        public string BuildNumber { get; init; }
+        public string? BuildNumber { get; init; }
 
-        public string FullNugetVersion { get; init; }
+        public string? FullNugetVersion { get; init; }
 
-        public string SdkFeatureBand { get; init; }
+        public string? SdkFeatureBand { get; init; }
 
         /// <summary>
         /// The runtime identifier (rid) that this CLI was built for.
@@ -24,7 +24,7 @@ internal class DotnetVersionFile
         /// RuntimeInformation.RuntimeIdentifier may be for a new version of the OS that
         /// doesn't have full support yet.
         /// </remarks>
-        public string BuildRid { get; init; }
+        public string? BuildRid { get; init; }
 
         public DotnetVersionFile(string versionFilePath)
         {

src/Cli/Microsoft.DotNet.Cli.Utils/Env.cs

@@ -15,17 +15,17 @@ public static IEnumerable<string> ExecutableExtensions
             }
         }
 
-        public static string GetCommandPath(string commandName, params string[] extensions)
+        public static string? GetCommandPath(string commandName, params string[] extensions)
         {
             return _environment.GetCommandPath(commandName, extensions);
         }
 
-        public static string GetCommandPathFromRootPath(string rootPath, string commandName, params string[] extensions)
+        public static string? GetCommandPathFromRootPath(string rootPath, string commandName, params string[] extensions)
         {
             return _environment.GetCommandPathFromRootPath(rootPath, commandName, extensions);
         }
 
-        public static string GetCommandPathFromRootPath(string rootPath, string commandName, IEnumerable<string> extensions)
+        public static string? GetCommandPathFromRootPath(string rootPath, string commandName, IEnumerable<string> extensions)
         {
             return _environment.GetCommandPathFromRootPath(rootPath, commandName, extensions);
         }
@@ -40,7 +40,7 @@ public static bool GetEnvironmentVariableAsBool(string name, bool defaultValue =
             return _environment.GetEnvironmentVariableAsNullableInt(name);
         }
 
-        public static string GetEnvironmentVariable(string name)
+        public static string? GetEnvironmentVariable(string name)
         {
             return _environment.GetEnvironmentVariable(name);
         }