Enable nullable referenrce types in DebugEngineHost

build/all_projects.settings.targets

@@ -21,6 +21,8 @@
     <ToolsHome>$(MIEngineRoot)\tools</ToolsHome>
     <IntermediateOutputPath>$(MIEngineRoot)obj\$(Configuration)\$(MSBuildProjectName)\</IntermediateOutputPath>
     <NuGetExePath>$(ToolsHome)\NuGet\NuGet.exe</NuGetExePath>
+    <!--NOTE: This is the same language version that is the default for .NET 8 projects -->
+    <LangVersion>12.0</LangVersion>
   </PropertyGroup>
 
   <!-- Source Link -->

src/DebugEngineHost.Common/HostLogChannel.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft. All rights reserved.
+// Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 /*
@@ -51,18 +51,18 @@ public interface ILogChannel
     public class HostLogChannel : ILogChannel
     {
         private readonly Action<string> _log;
-        private StreamWriter _logFile;
+        private StreamWriter? _logFile;
         private LogLevel _minLevelToBeLogged;
 
         private readonly object _lock = new object();
 
-        private HostLogChannel() { }
+        private HostLogChannel() { _log = null!; }
 
-        public HostLogChannel(Action<string> logAction, string file, LogLevel logLevel)
+        public HostLogChannel(Action<string> logAction, string? file, LogLevel logLevel)
         {
             _log = logAction;
 
-            if (!string.IsNullOrEmpty(file))
+            if (!IsNullOrEmpty(file))
             {
                 _logFile = File.CreateText(file);
             }

src/DebugEngineHost.Stub/DebugEngineHost.Stub.csproj

@@ -3,6 +3,7 @@
     <!--Fix the assembly version for DebugEngineHost as all the versions of this dll must have the same assembly identity
     NOTE: Ths must be set BEFORE improting miengine.settings.targets-->
     <AssemblyVersion>1.0.0</AssemblyVersion>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <Import Project="..\..\build\miengine.settings.targets" />
   <PropertyGroup>
@@ -23,6 +24,12 @@
 
   <Import Project="..\..\build\Debugger.PIAs.Portable.Packages.settings.targets" />
 
+  <ItemGroup>
+    <Compile Include="$(MIEngineRoot)\src\Shared\NullableAttributes.cs">
+      <Link>Shared\%(Filename).cs</Link>
+    </Compile>
+  </ItemGroup>
+
   <ItemGroup Label="NuGet Packages">
     <PackageReference Include="Microsoft.VisualStudioEng.MicroBuild.Core" Version="$(Microsoft_VisualStudioEng_MicroBuild_Core_Version)" GeneratePathProperty="true"/>
   </ItemGroup>

src/DebugEngineHost.Stub/DebugEngineHost.ref.cs

@@ -1,10 +1,10 @@
-// Copyright (c) Microsoft. All rights reserved.
+// Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using Microsoft.VisualStudio.Debugger.Interop;
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
+using ConditionalAttribute = global::System.Diagnostics.ConditionalAttribute;
 using System.Threading;
 
 
@@ -88,7 +88,7 @@ public void Dispose() { }
         /// <param name="valueName">Name of the value to obtain</param>
         /// <returns>[Optional] null if the value doesn't exist, otherwise the value
         /// </returns>
-        public object GetValue(string valueName)
+        public object? GetValue(string valueName)
         {
             throw new NotImplementedException();
         }
@@ -146,7 +146,7 @@ public string RegistryRoot
         /// </summary>
         /// <param name="metric">The metric to read.</param>
         /// <returns>[Optional] value of the metric. Null if the metric is not defined.</returns>
-        public object GetEngineMetric(string metric)
+        public object? GetEngineMetric(string metric)
         {
             throw new NotImplementedException();
         }
@@ -178,7 +178,7 @@ public T GetDebuggerConfigurationSetting<T>(string settingName, T defaultValue)
         /// </summary>
         /// <param name="launcherTypeName">launch options type name</param>
         /// <returns></returns>
-        public object GetCustomLauncher(string launcherTypeName)
+        public object? GetCustomLauncher(string launcherTypeName)
         {
             throw new NotImplementedException();
         }
@@ -277,8 +277,8 @@ public static void EnableNatvisDiagnostics(Action<string> callback, LogLevel lev
         /// <summary>
         /// Sets the log file to write to.
         /// </summary>
-        /// <param name="logFile">The file to write engine logs to.</param>
-        public static void SetEngineLogFile(string logFile)
+        /// <param name="logFile">The file to write engine logs to, or null if none</param>
+        public static void SetEngineLogFile(string? logFile)
         {
             throw new NotImplementedException();
         }
@@ -287,7 +287,7 @@ public static void SetEngineLogFile(string logFile)
         /// Gets the engine log channel created by 'EnableHostLogging'
         /// </summary>
         /// <returns>A logger object if logging is enabled, or null if it is not</returns>
-        public static ILogChannel GetEngineLogChannel()
+        public static ILogChannel? GetEngineLogChannel()
         {
             throw new NotImplementedException();
         }
@@ -296,7 +296,7 @@ public static ILogChannel GetEngineLogChannel()
         /// Gets the Natvis log channel if its been created.
         /// </summary>
         /// <returns>A logger object if logging is enabled, or null if it is not</returns>
-        public static ILogChannel GetNatvisLogChannel()
+        public static ILogChannel? GetNatvisLogChannel()
         {
             throw new NotImplementedException();
         }
@@ -339,7 +339,7 @@ public static class HostLoader
         /// <param name="clsid">CLSID to CoCreate</param>
         /// <returns>[Optional] loaded object. Null if the type is not registered, or points to a type that doesn't exist</returns>
         [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Co")]
-        public static object VsCoCreateManagedObject(HostConfigurationStore configStore, Guid clsid)
+        public static object? VsCoCreateManagedObject(HostConfigurationStore configStore, Guid clsid)
         {
             throw new NotImplementedException();
         }
@@ -472,15 +472,15 @@ public static void FindNatvis(NatvisLoader loader)
         /// <summary>
         /// Enable's tracking the VS 'Natvis Diagnostic Messages (C++ only)' setting.
         /// </summary>
-        public static IDisposable WatchNatvisOptionSetting(HostConfigurationStore configStore, ILogChannel natvisLogger)
+        public static IDisposable? WatchNatvisOptionSetting(HostConfigurationStore configStore, ILogChannel natvisLogger)
         {
             throw new NotImplementedException();
         }
 
         /// <summary>
         /// Return the solution's root directory, null if no solution
         /// </summary>
-        public static string FindSolutionRoot()
+        public static string? FindSolutionRoot()
         {
             throw new NotImplementedException();
         }
@@ -663,7 +663,7 @@ public static void SendEvent(string eventName, params KeyValuePair<string, objec
         /// </summary>
         /// <param name="currentException">Exception object to report.</param>
         /// <param name="engineName">Name of the engine reporting the exception. Ex:Microsoft.MIEngine</param>
-        public static void ReportCurrentException(Exception currentException, string engineName)
+        public static void ReportCurrentException(Exception currentException, string? engineName)
         {
             throw new NotImplementedException();
         }

src/DebugEngineHost.Stub/Shared/NullableHelpers.cs

@@ -0,0 +1,151 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+global using static global::Microsoft.DebugEngineHost.NullableHelpers;
+
+namespace Microsoft.DebugEngineHost
+{
+    using System.Diagnostics.CodeAnalysis;
+    using ConditionalAttribute = System.Diagnostics.ConditionalAttribute;
+    using SysDebug = System.Diagnostics.Debug;
+
+#pragma warning disable 8763 // A method marked [DoesNotReturn] should not return.
+
+    /// <summary>
+    /// Helper class to support nullable reference work when compiling against .NET Standard / .NET Framework
+    /// </summary>
+    public static class NullableHelpers
+    {
+        /// <summary>
+        /// Wrapper around string.IsNullOrEmpty to add the `[NotNullWhen(false)]` annotation
+        /// </summary>
+        /// <param name="s">string to test</param>
+        /// <returns>True if the string is null or empty</returns>
+        static public bool IsNullOrEmpty([NotNullWhen(false)] string? s)
+        {
+            return string.IsNullOrEmpty(s);
+        }
+
+        /// <summary>
+        /// Wrapper around string.IsNullOrWhiteSpace to add the `[NotNullWhen(false)]` annotation
+        /// </summary>
+        /// <param name="s">string to test</param>
+        /// <returns>True if the string is null, empty, or only whitespace</returns>
+        static public bool IsNullOrWhiteSpace([NotNullWhen(false)] string? s)
+        {
+            return string.IsNullOrWhiteSpace(s);
+        }
+
+        /// <summary>
+        /// This is a shim on top of the <see cref="System.Diagnostics.Debug"/> class which adds attributes used
+        /// in nullability analysis. This is important because without the DoesNotReturnIf/DoesNotReturn attributes,
+        /// on Debug.Assert/Debug.Fail the C# compiler will see code like:
+        /// <code>
+        /// Debug.Assert(myArg != null, "Invalid argument")
+        /// </code>
+        /// And decide that because the code was attempting to handle 'myArg' being null, that it must be possible
+        /// for it to be null.
+        /// </summary>
+        [System.Diagnostics.DebuggerNonUserCode()]
+        public static class Debug
+        {
+            /// <summary>
+            /// Checks for a condition; if the condition is false, displays a message box that shows the call stack.
+            /// </summary>
+            /// <param name="condition">The conditional expression to evaluate. If the condition is true, a failure message is not sent and the message box is not displayed.</param>
+            [Conditional("DEBUG")]
+            public static void Assert([DoesNotReturnIf(false)] bool condition)
+            {
+                SysDebug.Assert(condition);
+            }
+
+            /// <summary>
+            /// Checks for a condition; if the condition is false, outputs a specified message and displays a message box that shows the call stack.
+            /// </summary>
+            /// <param name="condition">The conditional expression to evaluate. If the condition is true, the specified message is not sent and the message box is not displayed.</param>
+            /// <param name="message">The message to send to the <see cref="System.Diagnostics.Trace.Listeners"/> collection.</param>
+            [Conditional("DEBUG")]
+            public static void Assert([DoesNotReturnIf(false)] bool condition, string message)
+            {
+                SysDebug.Assert(condition, message);
+            }
+
+            /// <summary>
+            /// Checks for a condition; if the condition is false, outputs two specified messages and displays a message box that shows the call stack.
+            /// </summary>
+            /// <param name="condition">The conditional expression to evaluate. If the condition is true, the specified messages are not sent and the message box is not displayed.</param>
+            /// <param name="message">The message to send to the <see cref="System.Diagnostics.Trace.Listeners"/> collection.</param>
+            /// <param name="detailMessage">The detailed message to send to the <see cref="System.Diagnostics.Trace.Listeners"/> collection.</param>
+            [Conditional("DEBUG")]
+            public static void Assert([DoesNotReturnIf(false)] bool condition, string message, string detailMessage)
+            {
+                SysDebug.Assert(condition, message, detailMessage);
+            }
+
+            /// <summary>
+            /// Emits the specified error message.
+            /// </summary>
+            /// <param name="message">A message to emit.</param>
+            [Conditional("DEBUG")]
+            [DoesNotReturn]
+            public static void Fail(string message)
+            {
+                SysDebug.Fail(message);
+            }
+
+            /// <summary>
+            /// Emits an error message and a detailed error message.
+            /// </summary>
+            /// <param name="message">A message to emit.</param>
+            /// <param name="detailMessage">A detailed message to emit.</param>
+            [Conditional("DEBUG")]
+            [DoesNotReturn]
+            public static void Fail(string message, string detailMessage)
+            {
+                SysDebug.Fail(message, detailMessage);
+            }
+
+            /// <summary>
+            /// Writes a message followed by a line terminator to the debugger.
+            /// </summary>
+            /// <param name="message">A message to write.</param>
+            [Conditional("DEBUG")]
+            public static void WriteLine(string message)
+            {
+                SysDebug.WriteLine(message);
+            }
+
+            /// <summary>
+            /// Writes the value of the object's <see cref="object.ToString"/> method to the debugger.
+            /// </summary>
+            /// <param name="value">An object whose value is sent to the debugger.</param>
+            [Conditional("DEBUG")]
+            public static void WriteLine(object value)
+            {
+                SysDebug.WriteLine(value);
+            }
+
+            /// <summary>
+            /// Writes a category name and message to the debugger.
+            /// </summary>
+            /// <param name="message">A message to write.</param>
+            /// <param name="category">A category name used to organize the output.</param>
+            [Conditional("DEBUG")]
+            public static void WriteLine(string message, string category)
+            {
+                SysDebug.WriteLine(message, category);
+            }
+
+            /// <summary>
+            /// Writes a category name and the value of the object's <see cref="object.ToString"/> method to the debugger.
+            /// </summary>
+            /// <param name="value">An object whose value is sent to the debugger.</param>
+            /// <param name="category">A category name used to organize the output.</param>
+            [Conditional("DEBUG")]
+            public static void WriteLine(object value, string category)
+            {
+                SysDebug.WriteLine(value, category);
+            }
+        }
+    }
+}

src/DebugEngineHost.VSCode/DebugEngineHost.VSCode.csproj

@@ -3,6 +3,7 @@
     <!--Fix the assembly version for DebugEngineHost as all the versions of this dll must have the same assembly identity
     NOTE: Ths must be set BEFORE importing miengine.settings.targets-->
     <AssemblyVersion>1.0.0</AssemblyVersion>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <Import Project="..\..\build\miengine.settings.targets" />
   <PropertyGroup>
@@ -20,11 +21,16 @@
     <TargetFramework>netstandard2.0</TargetFramework>
   </PropertyGroup>
 
-  <ItemGroup Label="Compile Shared Interfaces">
-    <Compile Include="$(MIEngineRoot)\src\DebugEngineHost.Stub\Shared\Microsoft.VisualStudio.Debugger.Interop.DAP.cs" />
-    <Compile Include="..\DebugEngineHost.Stub\Shared\Microsoft.VisualStudio.Debugger.Interop.MI.cs" Link="Microsoft.VisualStudio.Debugger.Interop.MI.cs" />
-
-    <Compile Include="$(MIEngineRoot)\src\DebugEngineHost.Common\HostLogChannel.cs" />
+  <ItemGroup>
+    <Compile Include="$(MIEngineRoot)\src\DebugEngineHost.Stub\Shared\*.cs">
+      <Link>Shared\%(Filename).cs</Link>
+    </Compile>
+    <Compile Include="$(MIEngineRoot)\src\DebugEngineHost.Common\*.cs">
+      <Link>Shared\%(Filename).cs</Link>
+    </Compile>
+    <Compile Include="$(MIEngineRoot)\src\Shared\NullableAttributes.cs">
+      <Link>Shared\%(Filename).cs</Link>
+    </Compile>
   </ItemGroup>
 
   <ItemGroup>

src/DebugEngineHost.VSCode/HostConfigurationSection.cs

@@ -21,7 +21,7 @@ public void Dispose()
             GC.SuppressFinalize(this);
         }
 
-        public object GetValue(string valueName)
+        public object? GetValue(string valueName)
         {
             ExceptionSettings.TriggerState state;
             if (_defaultTriggers.TryGetValue(valueName, out state))

src/DebugEngineHost.VSCode/HostConfigurationStore.cs

@@ -15,11 +15,12 @@ public sealed class HostConfigurationStore
 
         public HostConfigurationStore(string adapterId)
         {
-            _config = EngineConfiguration.TryGet(adapterId);
-            if (_config == null)
+            EngineConfiguration? config = EngineConfiguration.TryGet(adapterId);
+            if (config is null)
             {
                 throw new ArgumentOutOfRangeException(nameof(adapterId));
             }
+            _config = config;
         }
 
         public void SetEngineGuid(Guid value)
@@ -35,12 +36,12 @@ public string RegistryRoot
             }
         }
 
-        public object GetCustomLauncher(string launcherTypeName)
+        public object? GetCustomLauncher(string launcherTypeName)
         {
             throw new NotImplementedException();
         }
 
-        public object GetEngineMetric(string metric)
+        public object? GetEngineMetric(string metric)
         {
             if (string.CompareOrdinal("GlobalVisualizersDirectory", metric) == 0)
             {
@@ -55,7 +56,7 @@ public object GetEngineMetric(string metric)
         public void GetExceptionCategorySettings(Guid categoryId, out HostConfigurationSection categoryConfigSection, out string categoryName)
         {
             var category = _config.ExceptionSettings.Categories.FirstOrDefault((x) => x.Id == categoryId);
-            if (category == null)
+            if (category is null)
             {
                 throw new InvalidDataException(string.Format(CultureInfo.CurrentCulture, HostResources.Error_ExceptionCategoryMissing, categoryId));
             }