[dotnet watch] Auto-restart when project does not support Hot Reload

Directory.Packages.props

@@ -37,6 +37,7 @@
     <PackageVersion Include="Microsoft.CodeAnalysis.VisualBasic.Workspaces" Version="$(MicrosoftCodeAnalysisPackageVersion)" />
     <PackageVersion Include="Microsoft.CodeAnalysis.Workspaces.Common" Version="$(MicrosoftCodeAnalysisPackageVersion)" />
     <PackageVersion Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="$(MicrosoftCodeAnalysisWorkspacesMSBuildPackageVersion)" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.Workspaces.MSBuild.BuildHost" Version="$(MicrosoftCodeAnalysisWorkspacesMSBuildBuildHostPackageVersion)" />
     <PackageVersion Include="Microsoft.CodeAnalysis.ExternalAccess.HotReload" Version="$(MicrosoftCodeAnalysisExternalAccessHotReloadPackageVersion)" />
 
     <!-- roslyn-sdk dependencies-->

NuGet.config

@@ -35,6 +35,7 @@
     <add key="richnav" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vs-buildservices/nuget/v3/index.json" />
     <!-- mstest dependencies -->
     <add key="test-tools" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/test-tools/nuget/v3/index.json" />
+    <add key="R0" value="C:\R0\artifacts\packages\Debug\Shipping" />
   </packageSources>
   <disabledPackageSources>
     <clear />

eng/Version.Details.props

@@ -11,17 +11,18 @@ This file should be imported by eng/Versions.props
     <MicrosoftBuildLocalizationPackageVersion>18.3.0-preview-26076-108</MicrosoftBuildLocalizationPackageVersion>
     <MicrosoftBuildNuGetSdkResolverPackageVersion>7.3.0-preview.1.7708</MicrosoftBuildNuGetSdkResolverPackageVersion>
     <MicrosoftBuildTasksGitPackageVersion>10.0.300-alpha.26076.108</MicrosoftBuildTasksGitPackageVersion>
-    <MicrosoftCodeAnalysisPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisPackageVersion>
-    <MicrosoftCodeAnalysisBuildClientPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisBuildClientPackageVersion>
-    <MicrosoftCodeAnalysisCSharpPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisCSharpPackageVersion>
-    <MicrosoftCodeAnalysisCSharpCodeStylePackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisCSharpCodeStylePackageVersion>
-    <MicrosoftCodeAnalysisCSharpFeaturesPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisCSharpFeaturesPackageVersion>
-    <MicrosoftCodeAnalysisCSharpWorkspacesPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisCSharpWorkspacesPackageVersion>
-    <MicrosoftCodeAnalysisExternalAccessHotReloadPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisExternalAccessHotReloadPackageVersion>
-    <MicrosoftCodeAnalysisPublicApiAnalyzersPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisPublicApiAnalyzersPackageVersion>
+    <MicrosoftCodeAnalysisPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisPackageVersion>
+    <MicrosoftCodeAnalysisBuildClientPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisBuildClientPackageVersion>
+    <MicrosoftCodeAnalysisCSharpPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisCSharpPackageVersion>
+    <MicrosoftCodeAnalysisCSharpCodeStylePackageVersion>5.4.0-dev</MicrosoftCodeAnalysisCSharpCodeStylePackageVersion>
+    <MicrosoftCodeAnalysisCSharpFeaturesPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisCSharpFeaturesPackageVersion>
+    <MicrosoftCodeAnalysisCSharpWorkspacesPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisCSharpWorkspacesPackageVersion>
+    <MicrosoftCodeAnalysisWorkspacesMSBuildBuildHostPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisWorkspacesMSBuildBuildHostPackageVersion>
+    <MicrosoftCodeAnalysisExternalAccessHotReloadPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisExternalAccessHotReloadPackageVersion>
+    <MicrosoftCodeAnalysisPublicApiAnalyzersPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisPublicApiAnalyzersPackageVersion>
     <MicrosoftCodeAnalysisRazorToolingInternalPackageVersion>10.0.0-preview.26076.108</MicrosoftCodeAnalysisRazorToolingInternalPackageVersion>
-    <MicrosoftCodeAnalysisWorkspacesCommonPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisWorkspacesCommonPackageVersion>
-    <MicrosoftCodeAnalysisWorkspacesMSBuildPackageVersion>5.3.0-2.26076.108</MicrosoftCodeAnalysisWorkspacesMSBuildPackageVersion>
+    <MicrosoftCodeAnalysisWorkspacesCommonPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisWorkspacesCommonPackageVersion>
+    <MicrosoftCodeAnalysisWorkspacesMSBuildPackageVersion>5.4.0-dev</MicrosoftCodeAnalysisWorkspacesMSBuildPackageVersion>
     <MicrosoftDotNetArcadeSdkPackageVersion>10.0.0-beta.26076.108</MicrosoftDotNetArcadeSdkPackageVersion>
     <MicrosoftDotNetBuildTasksInstallersPackageVersion>10.0.0-beta.26076.108</MicrosoftDotNetBuildTasksInstallersPackageVersion>
     <MicrosoftDotNetBuildTasksTemplatingPackageVersion>10.0.0-beta.26076.108</MicrosoftDotNetBuildTasksTemplatingPackageVersion>
@@ -31,8 +32,8 @@ This file should be imported by eng/Versions.props
     <MicrosoftDotNetXliffTasksPackageVersion>10.0.0-beta.26076.108</MicrosoftDotNetXliffTasksPackageVersion>
     <MicrosoftDotNetXUnitExtensionsPackageVersion>10.0.0-beta.26076.108</MicrosoftDotNetXUnitExtensionsPackageVersion>
     <MicrosoftFSharpCompilerPackageVersion>15.2.300-servicing.26076.108</MicrosoftFSharpCompilerPackageVersion>
-    <MicrosoftNetCompilersToolsetPackageVersion>5.3.0-2.26076.108</MicrosoftNetCompilersToolsetPackageVersion>
-    <MicrosoftNetCompilersToolsetFrameworkPackageVersion>5.3.0-2.26076.108</MicrosoftNetCompilersToolsetFrameworkPackageVersion>
+    <MicrosoftNetCompilersToolsetPackageVersion>5.4.0-dev</MicrosoftNetCompilersToolsetPackageVersion>
+    <MicrosoftNetCompilersToolsetFrameworkPackageVersion>5.4.0-dev</MicrosoftNetCompilersToolsetFrameworkPackageVersion>
     <MicrosoftNETRuntimeEmscriptenSdkInternalPackageVersion>10.0.0-preview.7.25377.103</MicrosoftNETRuntimeEmscriptenSdkInternalPackageVersion>
     <MicrosoftNETSdkRazorSourceGeneratorsTransportPackageVersion>10.0.0-preview.26076.108</MicrosoftNETSdkRazorSourceGeneratorsTransportPackageVersion>
     <MicrosoftNETTestSdkPackageVersion>18.3.0-release-26076-108</MicrosoftNETTestSdkPackageVersion>

eng/Version.Details.xml

@@ -128,6 +128,10 @@
       <Uri>https://github.com/dotnet/dotnet</Uri>
       <Sha>3b3cc2b93b356d46a6fb36768479ea53515fc2cd</Sha>
     </Dependency>
+    <Dependency Name="Microsoft.CodeAnalysis.Workspaces.MSBuild.BuildHost" Version="5.3.0-2.25610.11">
+      <Uri>https://github.com/dotnet/roslyn</Uri>
+      <Sha>46a48b8c1dfce7c35da115308bedd6a5954fd78a</Sha>
+    </Dependency>
     <Dependency Name="NuGet.Build.Tasks" Version="7.3.0-preview.1.7708">
       <Uri>https://github.com/dotnet/dotnet</Uri>
       <Sha>3b3cc2b93b356d46a6fb36768479ea53515fc2cd</Sha>

src/BuiltInTools/HotReloadClient/DefaultHotReloadClient.cs

@@ -20,7 +20,7 @@
 
 namespace Microsoft.DotNet.HotReload
 {
-    internal sealed class DefaultHotReloadClient(ILogger logger, ILogger agentLogger, string startupHookPath, bool enableStaticAssetUpdates)
+    internal sealed class DefaultHotReloadClient(ILogger logger, ILogger agentLogger, string startupHookPath, bool handlesStaticAssetUpdates)
         : HotReloadClient(logger, agentLogger)
     {
         private readonly string _namedPipeName = Guid.NewGuid().ToString("N");
@@ -225,7 +225,7 @@ static ImmutableArray<RuntimeManagedCodeUpdate> ToRuntimeUpdates(IEnumerable<Hot
 
         public override async Task<Task<bool>> ApplyStaticAssetUpdatesAsync(ImmutableArray<HotReloadStaticAssetUpdate> updates, CancellationToken processExitedCancellationToken, CancellationToken cancellationToken)
         {
-            if (!enableStaticAssetUpdates)
+            if (!handlesStaticAssetUpdates)
             {
                 // The client has no concept of static assets.
                 return Task.FromResult(true);

src/BuiltInTools/HotReloadClient/HotReloadClients.cs

@@ -6,6 +6,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
@@ -16,13 +17,25 @@
 
 namespace Microsoft.DotNet.HotReload;
 
-internal sealed class HotReloadClients(ImmutableArray<(HotReloadClient client, string name)> clients, AbstractBrowserRefreshServer? browserRefreshServer) : IDisposable
+/// <summary>
+/// Facilitates Hot Reload updates across multiple clients/processes.
+/// </summary>
+/// <param name="clients">
+/// Clients that handle managed updates and static asset updates if <paramref name="useRefreshServerToApplyStaticAssets"/> is false.
+/// </param>
+/// <param name="browserRefreshServer">
+/// Browser refresh server used to communicate managed code update status and errors to the browser,
+/// and to apply static asset updates if <paramref name="useRefreshServerToApplyStaticAssets"/> is true.
+/// </param>
+/// <param name="useRefreshServerToApplyStaticAssets">
+/// True to use <paramref name="browserRefreshServer"/> to apply static asset updates (if available).
+/// False to use the <paramref name="clients"/> to apply static asset updates.
+/// </param>
+internal sealed class HotReloadClients(
+    ImmutableArray<(HotReloadClient client, string name)> clients,
+    AbstractBrowserRefreshServer? browserRefreshServer,
+    bool useRefreshServerToApplyStaticAssets) : IDisposable
 {
-    public HotReloadClients(HotReloadClient client, AbstractBrowserRefreshServer? browserRefreshServer)
-        : this([(client, "")], browserRefreshServer)
-    {
-    }
-
     /// <summary>
     /// Disposes all clients. Can occur unexpectedly whenever the process exits.
     /// </summary>
@@ -34,6 +47,16 @@ public void Dispose()
         }
     }
 
+    /// <summary>
+    /// True if Hot Reload is implemented via managed agents.
+    /// The update itself might not be managed code update, it may be a static asset update implemented via a managed agent.
+    /// </summary>
+    public bool IsManagedAgentSupported
+        => !clients.IsEmpty;
+
+    public bool UseRefreshServerToApplyStaticAssets
+        => useRefreshServerToApplyStaticAssets;
+
     public AbstractBrowserRefreshServer? BrowserRefreshServer
         => browserRefreshServer;
 
@@ -59,18 +82,6 @@ public event Action<int, string> OnRuntimeRudeEdit
         }
     }
 
-    /// <summary>
-    /// All clients share the same loggers.
-    /// </summary>
-    public ILogger ClientLogger
-        => clients.First().client.Logger;
-
-    /// <summary>
-    /// All clients share the same loggers.
-    /// </summary>
-    public ILogger AgentLogger
-        => clients.First().client.AgentLogger;
-
     internal void ConfigureLaunchEnvironment(IDictionary<string, string> environmentBuilder)
     {
         foreach (var (client, _) in clients)
@@ -99,6 +110,12 @@ internal async ValueTask WaitForConnectionEstablishedAsync(CancellationToken can
     /// <param name="cancellationToken">Cancellation token. The cancellation should trigger on process terminatation.</param>
     public async ValueTask<ImmutableArray<string>> GetUpdateCapabilitiesAsync(CancellationToken cancellationToken)
     {
+        if (!IsManagedAgentSupported)
+        {
+            // empty capabilities will cause rude edit ENC0097: NotSupportedByRuntime.
+            return [];
+        }
+
         if (clients is [var (singleClient, _)])
         {
             return await singleClient.GetUpdateCapabilitiesAsync(cancellationToken);
@@ -114,6 +131,9 @@ public async ValueTask<ImmutableArray<string>> GetUpdateCapabilitiesAsync(Cancel
     /// <param name="cancellationToken">Cancellation token. The cancellation should trigger on process terminatation.</param>
     public async Task<Task> ApplyManagedCodeUpdatesAsync(ImmutableArray<HotReloadManagedCodeUpdate> updates, CancellationToken applyOperationCancellationToken, CancellationToken cancellationToken)
     {
+        // shouldn't be called if there are no clients
+        Debug.Assert(IsManagedAgentSupported);
+
         // Apply to all processes.
         // The module the change is for does not need to be loaded to any of the processes, yet we still consider it successful if the application does not fail.
         // In each process we store the deltas for application when/if the module is loaded to the process later.
@@ -137,6 +157,9 @@ async Task CompleteApplyOperationAsync()
     /// <param name="cancellationToken">Cancellation token. The cancellation should trigger on process terminatation.</param>
     public async ValueTask InitialUpdatesAppliedAsync(CancellationToken cancellationToken)
     {
+        // shouldn't be called if there are no clients
+        Debug.Assert(IsManagedAgentSupported);
+
         if (clients is [var (singleClient, _)])
         {
             await singleClient.InitialUpdatesAppliedAsync(cancellationToken);
@@ -150,23 +173,26 @@ public async ValueTask InitialUpdatesAppliedAsync(CancellationToken cancellation
     /// <param name="cancellationToken">Cancellation token. The cancellation should trigger on process terminatation.</param>
     public async Task<Task> ApplyStaticAssetUpdatesAsync(IEnumerable<StaticWebAsset> assets, CancellationToken applyOperationCancellationToken, CancellationToken cancellationToken)
     {
-        if (browserRefreshServer != null)
+        if (useRefreshServerToApplyStaticAssets)
         {
+            Debug.Assert(browserRefreshServer != null);
             return browserRefreshServer.UpdateStaticAssetsAsync(assets.Select(static a => a.RelativeUrl), applyOperationCancellationToken).AsTask();
         }
 
+        // shouldn't be called if there are no clients
+        Debug.Assert(IsManagedAgentSupported);
+
         var updates = new List<HotReloadStaticAssetUpdate>();
 
         foreach (var asset in assets)
         {
             try
             {
-                ClientLogger.LogDebug("Loading asset '{Url}' from '{Path}'.", asset.RelativeUrl, asset.FilePath);
                 updates.Add(await HotReloadStaticAssetUpdate.CreateAsync(asset, cancellationToken));
             }
             catch (Exception e) when (e is not OperationCanceledException)
             {
-                ClientLogger.LogError("Failed to read file {FilePath}: {Message}", asset.FilePath, e.Message);
+                clients.First().client.Logger.LogError("Failed to read file {FilePath}: {Message}", asset.FilePath, e.Message);
                 continue;
             }
         }
@@ -177,6 +203,10 @@ public async Task<Task> ApplyStaticAssetUpdatesAsync(IEnumerable<StaticWebAsset>
     /// <param name="cancellationToken">Cancellation token. The cancellation should trigger on process terminatation.</param>
     public async ValueTask<Task> ApplyStaticAssetUpdatesAsync(ImmutableArray<HotReloadStaticAssetUpdate> updates, CancellationToken applyOperationCancellationToken, CancellationToken cancellationToken)
     {
+        // shouldn't be called if there are no clients
+        Debug.Assert(IsManagedAgentSupported);
+        Debug.Assert(!useRefreshServerToApplyStaticAssets);
+
         var applyTasks = await Task.WhenAll(clients.Select(c => c.client.ApplyStaticAssetUpdatesAsync(updates, applyOperationCancellationToken, cancellationToken)));
 
         return Task.WhenAll(applyTasks);

src/BuiltInTools/HotReloadClient/StaticAsset.cs

@@ -0,0 +1,14 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable enable
+
+namespace Microsoft.DotNet.HotReload;
+
+internal readonly struct StaticAsset(string filePath, string relativeUrl, string assemblyName, bool isApplicationProject)
+{
+    public string FilePath => filePath;
+    public string RelativeUrl => relativeUrl;
+    public string AssemblyName => assemblyName;
+    public bool IsApplicationProject => isApplicationProject;
+}

src/BuiltInTools/Watch/AppModels/BlazorWebAssemblyAppModel.cs

@@ -17,11 +17,11 @@ internal sealed class BlazorWebAssemblyAppModel(DotNetWatchContext context, Proj
 {
     public override ProjectGraphNode LaunchingProject => clientProject;
 
-    public override bool RequiresBrowserRefresh => true;
+    public override bool ManagedHotReloadRequiresBrowserRefresh => true;
 
-    protected override HotReloadClients CreateClients(ILogger clientLogger, ILogger agentLogger, BrowserRefreshServer? browserRefreshServer)
+    protected override ImmutableArray<(HotReloadClient client, string name)> CreateManagedClients(ILogger clientLogger, ILogger agentLogger, BrowserRefreshServer? browserRefreshServer)
     {
         Debug.Assert(browserRefreshServer != null);
-        return new(CreateWebAssemblyClient(clientLogger, agentLogger, browserRefreshServer, clientProject), browserRefreshServer);
+        return [(CreateWebAssemblyClient(clientLogger, agentLogger, browserRefreshServer, clientProject), "")];
     }
 }

src/BuiltInTools/Watch/AppModels/BlazorWebAssemblyHostedAppModel.cs

@@ -19,17 +19,16 @@ internal sealed class BlazorWebAssemblyHostedAppModel(DotNetWatchContext context
 {
     public override ProjectGraphNode LaunchingProject => serverProject;
 
-    public override bool RequiresBrowserRefresh => true;
+    public override bool ManagedHotReloadRequiresBrowserRefresh => true;
 
-    protected override HotReloadClients CreateClients(ILogger clientLogger, ILogger agentLogger, BrowserRefreshServer? browserRefreshServer)
+    protected override ImmutableArray<(HotReloadClient client, string name)> CreateManagedClients(ILogger clientLogger, ILogger agentLogger, BrowserRefreshServer? browserRefreshServer)
     {
         Debug.Assert(browserRefreshServer != null);
 
-        return new(
-            [
-                (CreateWebAssemblyClient(clientLogger, agentLogger, browserRefreshServer, clientProject), "client"),
-                (new DefaultHotReloadClient(clientLogger, agentLogger, GetStartupHookPath(serverProject), enableStaticAssetUpdates: false), "host")
-            ],
-            browserRefreshServer);
+        return
+        [
+            (CreateWebAssemblyClient(clientLogger, agentLogger, browserRefreshServer, clientProject), "client"),
+            (new DefaultHotReloadClient(clientLogger, agentLogger, GetStartupHookPath(serverProject), handlesStaticAssetUpdates: false), "host")
+        ];
     }
 }

src/BuiltInTools/Watch/AppModels/DefaultAppModel.cs

@@ -12,6 +12,11 @@ namespace Microsoft.DotNet.Watch;
 /// </summary>
 internal sealed class DefaultAppModel(ProjectGraphNode project) : HotReloadAppModel
 {
-    public override ValueTask<HotReloadClients?> TryCreateClientsAsync(ILogger clientLogger, ILogger agentLogger, CancellationToken cancellationToken)
-        => new(new HotReloadClients(new DefaultHotReloadClient(clientLogger, agentLogger, GetStartupHookPath(project), enableStaticAssetUpdates: true), browserRefreshServer: null));
+    public override ValueTask<HotReloadClients> CreateClientsAsync(ILogger clientLogger, ILogger agentLogger, CancellationToken cancellationToken)
+        => new(new HotReloadClients(
+            clients: IsManagedAgentSupported(project, clientLogger)
+                ? [(new DefaultHotReloadClient(clientLogger, agentLogger, GetStartupHookPath(project), handlesStaticAssetUpdates: true), "")]
+                : [],
+            browserRefreshServer: null,
+            useRefreshServerToApplyStaticAssets: false));
 }