Update GenerateRuntimeConfigurationFiles task to generate Hot Reload runtime options

src/Dotnet.Watch/Watch/AppModels/HotReloadAppModel.cs

@@ -64,39 +64,50 @@ internal static bool IsManagedAgentSupported(ProjectGraphNode project, ILogger l
             return false;
         }
 
-        // If property is not specified startup hook is enabled:
-        // https://github.com/dotnet/runtime/blob/4b0b7238ba021b610d3963313b4471517108d2bc/src/libraries/System.Private.CoreLib/src/System/StartupHookProvider.cs#L22
-        // Startup hooks are not used for WASM projects.
-        //
-        // TODO: Remove once implemented: https://github.com/dotnet/runtime/issues/123778
-        if (!project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.StartupHookSupport, defaultValue: true) &&
-            !project.GetCapabilities().Contains(ProjectCapability.WebAssembly))
-        {
-            // Report which property is causing lack of support for startup hooks:
-            var (propertyName, propertyValue) =
-                project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.PublishAot)
-                ? (PropertyNames.PublishAot, true)
-                : project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.PublishTrimmed)
-                ? (PropertyNames.PublishTrimmed, true)
-                : (PropertyNames.StartupHookSupport, false);
-
-            logger.Log(MessageDescriptor.ProjectDoesNotSupportHotReload_Property, propertyName, propertyValue.ToString(), PropertyNames.StartupHookSupport, "True");
-            return false;
-        }
-
-        // MetadataUpdaterSupport is the primary indicator of whether the runtime supports Hot Reload.
-        // It is however not correctly set prior to .NET 11, so we use Optimize and DebugSymbols instead for older frameworks.
-        // See https://github.com/dotnet/runtime/pull/127163
+        // Since .NET 11 the SDK generates runtimeconfig.dev.json file that configures the runtime to support
+        // startup hooks and metadata update handlers in Debug builds.
+        // The file is generated when the property EnableHotReloadInRuntimeConfigDevFile is true.
         if (project.IsNetCoreApp(Versions.Version11_0))
         {
-            if (!project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.MetadataUpdaterSupport, defaultValue: true))
+            if (!project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.EnableHotReloadInRuntimeConfigDevFile, defaultValue: true))
             {
-                logger.Log(MessageDescriptor.ProjectDoesNotSupportHotReload_Property, PropertyNames.MetadataUpdaterSupport, "False", PropertyNames.MetadataUpdaterSupport, "True");
-                return false;
+                // If runtimeconfig.dev.json file is not generated MetadataUpdaterSupport and StartupHookSupport need to be enabled.
+                var metadataUpdaterSupported = project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.MetadataUpdaterSupport, defaultValue: true);
+                if (!metadataUpdaterSupported || !StartupHookSupportedIfRequired())
+                {
+                    logger.Log(
+                        MessageDescriptor.ProjectDoesNotSupportHotReload_Property,
+                        // setting blocking Hot Reload:
+                        metadataUpdaterSupported ? PropertyNames.StartupHookSupport : PropertyNames.MetadataUpdaterSupport,
+                        "False",
+                        // recommended setting:
+                        PropertyNames.EnableHotReloadInRuntimeConfigDevFile,
+                        "True");
+
+                    return false;
+                }
             }
         }
         else
         {
+            if (!StartupHookSupportedIfRequired())
+            {
+                // Report which property is causing lack of support for startup hooks:
+                var (propertyName, propertyValue) =
+                    project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.PublishAot)
+                    ? (PropertyNames.PublishAot, true)
+                    : project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.PublishTrimmed)
+                    ? (PropertyNames.PublishTrimmed, true)
+                    : (PropertyNames.StartupHookSupport, false);
+
+                logger.Log(MessageDescriptor.ProjectDoesNotSupportHotReload_Property, propertyName, propertyValue.ToString(), PropertyNames.StartupHookSupport, "True");
+                return false;
+            }
+
+            // Not checking MetadataUpdateSupport since it's not set correctly prior .NET 11.
+            // Use Optimize and DebugSymbols instead for older frameworks.
+            // See https://github.com/dotnet/runtime/pull/127163
+
             if (project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.Optimize))
             {
                 logger.Log(MessageDescriptor.ProjectDoesNotSupportHotReload_Property, PropertyNames.Optimize, "True", PropertyNames.Optimize, "False");
@@ -111,5 +122,10 @@ internal static bool IsManagedAgentSupported(ProjectGraphNode project, ILogger l
         }
 
         return true;
+
+        bool StartupHookSupportedIfRequired()
+            => project.ProjectInstance.GetBooleanPropertyValue(PropertyNames.StartupHookSupport, defaultValue: true) ||
+               // Startup hooks are not used for WASM projects.
+               project.GetCapabilities().Contains(ProjectCapability.WebAssembly);
     }
 }

src/Dotnet.Watch/Watch/Build/BuildNames.cs

@@ -29,6 +29,7 @@ internal static class PropertyNames
     public const string DebugSymbols = nameof(DebugSymbols);
     public const string PublishTrimmed = nameof(PublishTrimmed);
     public const string PublishAot = nameof(PublishAot);
+    public const string EnableHotReloadInRuntimeConfigDevFile = nameof(EnableHotReloadInRuntimeConfigDevFile);
 }
 
 internal static class ItemNames

src/Tasks/Microsoft.NET.Build.Tasks/GenerateRuntimeConfigurationFiles.cs

@@ -53,7 +53,18 @@ public class GenerateRuntimeConfigurationFiles : TaskBase, IMultiThreadableTask
 
         public bool WriteIncludedFrameworks { get; set; }
 
-        public bool GenerateRuntimeConfigDevFile { get; set; }
+        /// <summary>
+        /// True to generate probing paths to runtimeconfig.dev.json file.
+        /// </summary>
+        public bool GenerateProbingPathsToRuntimeConfigDevFile { get; set; }
+
+        /// <summary>
+        /// True to generate switches that enable Hot Reload to runtimeconfig.dev.json file.
+        /// </summary>
+        public bool GenerateHotReloadRuntimeOptionsToRuntimeConfigDevFile { get; set; }
+
+        private bool GenerateRuntimeConfigDevFile =>
+            GenerateProbingPathsToRuntimeConfigDevFile || GenerateHotReloadRuntimeOptionsToRuntimeConfigDevFile;
 
         public bool AlwaysIncludeCoreFramework { get; set; }
 
@@ -84,7 +95,7 @@ protected override void ExecuteCore()
                 // If we want to generate the runtimeconfig.dev.json file
                 // and we have additional probing paths to add to it
                 // BUT the runtimeconfigdevpath is empty, log a warning.
-                if (GenerateRuntimeConfigDevFile && AdditionalProbingPaths?.Any() == true && string.IsNullOrEmpty(RuntimeConfigDevPath))
+                if (GenerateProbingPathsToRuntimeConfigDevFile && AdditionalProbingPaths?.Any() == true && string.IsNullOrEmpty(RuntimeConfigDevPath))
                 {
                     Log.LogWarning(Strings.SkippingAdditionalProbingPaths);
                 }
@@ -342,7 +353,17 @@ private void WriteDevRuntimeConfig(IList<LockFileItem> packageFolders)
                 RuntimeOptions = new RuntimeOptions()
             };
 
-            AddAdditionalProbingPaths(devConfig.RuntimeOptions, packageFolders);
+            if (GenerateProbingPathsToRuntimeConfigDevFile)
+            {
+                AddAdditionalProbingPaths(devConfig.RuntimeOptions, packageFolders);
+            }
+
+            if (GenerateHotReloadRuntimeOptionsToRuntimeConfigDevFile)
+            {
+                JsonObject configProperties = GetConfigProperties(devConfig.RuntimeOptions);
+                configProperties["System.Reflection.Metadata.MetadataUpdater.IsSupported"] = true;
+                configProperties["System.StartupHookProvider.IsSupported"] = true;
+            }
 
             WriteToJsonFile(TaskEnvironment.GetAbsolutePath(RuntimeConfigDevPath), devConfig);
             _filesWritten.Add(new TaskItem(RuntimeConfigDevPath));

src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.targets

@@ -74,19 +74,26 @@ Copyright (c) .NET Foundation. All rights reserved.
     <ProjectConfigurationDescription Include="TargetFramework=$(TargetFramework)" />
   </ItemGroup>
 
+  <!-- Compatibility: if GenerateRuntimeConfigDevFile was set to true prior to adding GenerateProbingPathsToRuntimeConfigDevFile switch, the additional probing paths were generated -->
+  <PropertyGroup Condition="'$(GenerateRuntimeConfigDevFile)' == 'true'">
+    <GenerateProbingPathsToRuntimeConfigDevFile Condition="'$(GenerateProbingPathsToRuntimeConfigDevFile)' == ''">true</GenerateProbingPathsToRuntimeConfigDevFile>
+  </PropertyGroup>
+
   <PropertyGroup Condition="'$(GenerateRuntimeConfigDevFile)' == ''">
-    <GenerateRuntimeConfigDevFile>true</GenerateRuntimeConfigDevFile>
     <!-- Post-net6.0, stop generating *.runtimeconfig.dev.json files to reduce probing paths. -->
     <!-- https://github.com/dotnet/sdk/issues/16818 -->
-    <GenerateRuntimeConfigDevFile Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' and $([MSBuild]::VersionGreaterThanOrEquals($(TargetFrameworkVersion), '6.0'))">false</GenerateRuntimeConfigDevFile>
+    <GenerateProbingPathsToRuntimeConfigDevFile Condition="'$(GenerateProbingPathsToRuntimeConfigDevFile)' == '' and ('$(TargetFrameworkIdentifier)' != '.NETCoreApp' or $([MSBuild]::VersionLessThan($(TargetFrameworkVersion), '6.0')))">true</GenerateProbingPathsToRuntimeConfigDevFile>
+    <EnableHotReloadInRuntimeConfigDevFile Condition="'$(EnableHotReloadInRuntimeConfigDevFile)' == '' and '$(Configuration)' == 'Debug'">true</EnableHotReloadInRuntimeConfigDevFile>
+
+    <GenerateRuntimeConfigDevFile Condition="'$(GenerateProbingPathsToRuntimeConfigDevFile)' == 'true' or '$(EnableHotReloadInRuntimeConfigDevFile)' == 'true'">true</GenerateRuntimeConfigDevFile>
   </PropertyGroup>
 
   <PropertyGroup>
     <ProjectDepsFileName Condition="'$(ProjectDepsFileName)' == ''">$(AssemblyName).deps.json</ProjectDepsFileName>
     <ProjectDepsFilePath Condition="'$(ProjectDepsFilePath)' == ''">$(TargetDir)$(ProjectDepsFileName)</ProjectDepsFilePath>
     <ProjectRuntimeConfigFileName Condition="'$(ProjectRuntimeConfigFileName)' == ''">$(AssemblyName).runtimeconfig.json</ProjectRuntimeConfigFileName>
     <ProjectRuntimeConfigFilePath Condition="'$(ProjectRuntimeConfigFilePath)' == ''">$(TargetDir)$(ProjectRuntimeConfigFileName)</ProjectRuntimeConfigFilePath>
-    <ProjectRuntimeConfigDevFilePath Condition="'$(ProjectRuntimeConfigDevFilePath)' == '' and $(GenerateRuntimeConfigDevFile) == 'true'">$(TargetDir)$(AssemblyName).runtimeconfig.dev.json</ProjectRuntimeConfigDevFilePath>
+    <ProjectRuntimeConfigDevFilePath Condition="'$(ProjectRuntimeConfigDevFilePath)' == '' and '$(GenerateRuntimeConfigDevFile)' == 'true'">$(TargetDir)$(AssemblyName).runtimeconfig.dev.json</ProjectRuntimeConfigDevFilePath>
     <IncludeMainProjectInDepsFile Condition=" '$(IncludeMainProjectInDepsFile)' == '' ">true</IncludeMainProjectInDepsFile>
     <TrimDepsJsonLibrariesWithoutAssets Condition=" '$(TrimDepsJsonLibrariesWithoutAssets)' == '' ">true</TrimDepsJsonLibrariesWithoutAssets>
   </PropertyGroup>
@@ -354,6 +361,8 @@ Copyright (c) .NET Foundation. All rights reserved.
       <_GenerateRuntimeConfigurationPropertyInputsCacheToHash Include="$(SelfContained)"/>
       <_GenerateRuntimeConfigurationPropertyInputsCacheToHash Include="$(TargetFramework)"/>
       <_GenerateRuntimeConfigurationPropertyInputsCacheToHash Include="$(UserRuntimeConfig)"/>
+      <_GenerateRuntimeConfigurationPropertyInputsCacheToHash Include="$(GenerateProbingPathsToRuntimeConfigDevFile)"/>
+      <_GenerateRuntimeConfigurationPropertyInputsCacheToHash Include="$(EnableHotReloadInRuntimeConfigDevFile)"/>
       <_GenerateRuntimeConfigurationPropertyInputsCacheToHash Include="$(_WriteIncludedFrameworks)"/>
     </ItemGroup>
 
@@ -415,7 +424,8 @@ Copyright (c) .NET Foundation. All rights reserved.
                                        AdditionalProbingPaths="@(AdditionalProbingPath)"
                                        IsSelfContained="$(SelfContained)"
                                        WriteIncludedFrameworks="$(_WriteIncludedFrameworks)"
-                                       GenerateRuntimeConfigDevFile="$(GenerateRuntimeConfigDevFile)"
+                                       GenerateProbingPathsToRuntimeConfigDevFile="$(GenerateProbingPathsToRuntimeConfigDevFile)"
+                                       GenerateHotReloadRuntimeOptionsToRuntimeConfigDevFile="$(EnableHotReloadInRuntimeConfigDevFile)"
                                        AlwaysIncludeCoreFramework="$(AlwaysIncludeCoreFrameworkInRuntimeConfig)">
 
     </GenerateRuntimeConfigurationFiles>

test/Microsoft.DotNet.HotReload.Test.Utilities/WatchableApp.cs

@@ -119,31 +119,31 @@ public async ValueTask<string> WaitUntilOutputContains(MessageDescriptor descrip
             return matchingLine;
         }
 
-        public Task<string> WaitForOutputLineContaining(string text, [CallerFilePath] string? testPath = null, [CallerLineNumber] int testLine = 0)
+        public async Task<string> WaitForOutputLineContaining(string text, [CallerFilePath] string? testPath = null, [CallerLineNumber] int testLine = 0)
         {
             LogWaitingForOutput(text, testPath, testLine);
-            var line = Process.GetRequiredOutputLineAsync(line => line.Contains(text));
+            var line = await Process.GetRequiredOutputLineAsync(line => line.Contains(text));
             LogFoundOutput(text, testPath, testLine);
             return line;
         }
 
-        public Task<string> WaitForOutputLineContaining(MessageDescriptor descriptor, string? projectDisplay = null, [CallerLineNumber] int testLine = 0, [CallerFilePath] string? testPath = null)
+        public async Task<string> WaitForOutputLineContaining(MessageDescriptor descriptor, string? projectDisplay = null, [CallerLineNumber] int testLine = 0, [CallerFilePath] string? testPath = null)
         {
             var pattern = GetPattern(descriptor, projectDisplay, out var patternDisplay);
 
             LogWaitingForOutput(patternDisplay, testPath, testLine);
-            var line = Process.GetRequiredOutputLineAsync(line => pattern.IsMatch(line));
+            var line = await Process.GetRequiredOutputLineAsync(line => pattern.IsMatch(line));
             LogFoundOutput(patternDisplay, testPath, testLine);
 
             return line;
         }
 
-        public Task<string> WaitForOutputLineContaining(Regex pattern, [CallerFilePath] string? testPath = null, [CallerLineNumber] int testLine = 0)
+        public async Task<string> WaitForOutputLineContaining(Regex pattern, [CallerFilePath] string? testPath = null, [CallerLineNumber] int testLine = 0)
         {
             var patternDisplay = pattern.ToString();
 
             LogWaitingForOutput(patternDisplay, testPath, testLine);
-            var line = Process.GetRequiredOutputLineAsync(line => pattern.IsMatch(line));
+            var line = await Process.GetRequiredOutputLineAsync(line => pattern.IsMatch(line));
             LogFoundOutput(patternDisplay, testPath, testLine);
 
             return line;