Implements target framework selection for multi-targeted projects

src/Dotnet.Watch/HotReloadClient/Logging/LogEvents.cs

@@ -76,5 +76,6 @@ public static void Log<TArg1, TArg2, TArg3>(this ILogger logger, LogEvent<(TArg1
     public static readonly LogEvent<string> SendingStaticAssetUpdateRequest = Create<string>(LogLevel.Debug, "Sending static asset update request to connected browsers: '{0}'.");
     public static readonly LogEvent<string> RefreshServerRunningAt = Create<string>(LogLevel.Debug, "Refresh server running at {0}.");
     public static readonly LogEvent<None> ConnectedToRefreshServer = Create(LogLevel.Debug, "Connected to refresh server.");
+    public static readonly LogEvent<string> ManifestFileNotFound = Create<string>(LogLevel.Debug, "Manifest file '{0}' not found.");
 }
 

src/Dotnet.Watch/HotReloadClient/Web/StaticWebAssetsManifest.cs

@@ -92,7 +92,7 @@ public bool TryGetBundleFilePath(string bundleFileName, [NotNullWhen(true)] out
         }
         catch (FileNotFoundException)
         {
-            logger.LogDebug("File '{FilePath}' does not exist.", path);
+            logger.Log(LogEvents.ManifestFileNotFound, path);
             return null;
         }
         catch (Exception e)

src/Dotnet.Watch/Watch.Aspire/Server/AspireWatcherLauncher.cs

@@ -31,7 +31,6 @@ protected async Task<int> LaunchWatcherAsync(
             EnvironmentOptions = EnvironmentOptions,
             MainProjectOptions = null,
             BuildArguments = [],
-            TargetFramework = null,
             RootProjects = rootProjects,
             BrowserRefreshServerFactory = new BrowserRefreshServerFactory(),
             BrowserLauncher = new BrowserLauncher(logger, Reporter, EnvironmentOptions),

src/Dotnet.Watch/Watch/Build/EvaluationResult.cs

@@ -17,39 +17,26 @@ internal sealed class EvaluationResult(
     IReadOnlyDictionary<ProjectInstanceId, StaticWebAssetsManifest> staticWebAssetsManifests,
     ProjectBuildManager buildManager)
 {
-    public readonly IReadOnlyDictionary<string, FileItem> Files = files;
-    public readonly LoadedProjectGraph ProjectGraph = projectGraph;
-    public readonly ProjectBuildManager BuildManager = buildManager;
+    public IReadOnlyDictionary<string, FileItem> Files => files;
+    public LoadedProjectGraph ProjectGraph => projectGraph;
+    public ProjectBuildManager BuildManager => buildManager;
 
     public readonly FilePathExclusions ItemExclusions
         = projectGraph != null ? FilePathExclusions.Create(projectGraph.Graph) : FilePathExclusions.Empty;
 
-    private readonly Lazy<IReadOnlySet<string>> _lazyBuildFiles
-        = new(() => projectGraph != null ? CreateBuildFileSet(projectGraph.Graph) : new HashSet<string>());
-
-    private static IReadOnlySet<string> CreateBuildFileSet(ProjectGraph projectGraph)
-        => projectGraph.ProjectNodes.SelectMany(p => p.ProjectInstance.ImportPaths)
-            .Concat(projectGraph.ProjectNodes.Select(p => p.ProjectInstance.FullPath))
-            .ToHashSet(PathUtilities.OSSpecificPathComparer);
-
-    public IReadOnlySet<string> BuildFiles
-        => _lazyBuildFiles.Value;
-
     public IReadOnlyDictionary<ProjectInstanceId, StaticWebAssetsManifest> StaticWebAssetsManifests
         => staticWebAssetsManifests;
 
     public IReadOnlyDictionary<ProjectInstanceId, ProjectInstance> RestoredProjectInstances
         => restoredProjectInstances;
 
-    public void WatchFiles(FileWatcher fileWatcher)
+    public void WatchFileItems(FileWatcher fileWatcher)
     {
         fileWatcher.WatchContainingDirectories(Files.Keys, includeSubdirectories: true);
 
         fileWatcher.WatchContainingDirectories(
             StaticWebAssetsManifests.Values.SelectMany(static manifest => manifest.DiscoveryPatterns.Select(static pattern => pattern.Directory)),
             includeSubdirectories: true);
-
-        fileWatcher.WatchFiles(BuildFiles);
     }
 
     public static ImmutableDictionary<string, string> GetGlobalBuildProperties(IEnumerable<string> buildArguments, EnvironmentOptions environmentOptions)
@@ -70,31 +57,24 @@ public static ImmutableDictionary<string, string> GetGlobalBuildProperties(IEnum
     /// Loads project graph and performs design-time build.
     /// </summary>
     public static async ValueTask<EvaluationResult?> TryCreateAsync(
-        ProjectGraphFactory factory,
+        LoadedProjectGraph projectGraph,
+        ILogger logger,
         GlobalOptions globalOptions,
         EnvironmentOptions environmentOptions,
+        string? mainProjectTargetFramework,
         bool restore,
         CancellationToken cancellationToken)
     {
-        var logger = factory.Logger;
-        var stopwatch = Stopwatch.StartNew();
+        logger.Log(MessageDescriptor.LoadingProjects);
 
-        var projectGraph = factory.TryLoadProjectGraph(projectGraphRequired: true, cancellationToken);
-
-        if (projectGraph == null)
-        {
-            return null;
-        }
+        var projectLoadingStopwatch = Stopwatch.StartNew();
+        var stopwatch = Stopwatch.StartNew();
 
         var buildReporter = new BuildReporter(projectGraph.Logger, globalOptions, environmentOptions);
         var buildManager = new ProjectBuildManager(projectGraph.ProjectCollection, buildReporter);
 
-        logger.LogDebug("Project graph loaded in {Time}s.", stopwatch.Elapsed.TotalSeconds.ToString("0.0"));
-
         if (restore)
         {
-            stopwatch.Restart();
-
             var restoreRequests = projectGraph.Graph.GraphRoots.Select(node => BuildRequest.Create(node.ProjectInstance, [TargetNames.Restore])).ToArray();
 
             if (await buildManager.BuildAsync(
@@ -128,7 +108,17 @@ public static ImmutableDictionary<string, string> GetGlobalBuildProperties(IEnum
 
         var buildRequests =
            (from node in projectGraph.Graph.ProjectNodesTopologicallySorted
-            where node.ProjectInstance.GetPropertyValue(PropertyNames.TargetFramework) != ""
+            let targetFramework = node.ProjectInstance.GetTargetFramework()
+
+            // skip outer-build projects
+            where targetFramework != ""
+
+            // skip root projects that do not match main project TFM, if specified:
+            where mainProjectTargetFramework == null ||
+                  targetFramework == mainProjectTargetFramework ||
+                  node.ReferencingProjects.Count != 1 ||
+                  !node.ReferencingProjects.First().IsRoot
+
             let targets = GetBuildTargets(node.ProjectInstance, environmentOptions)
             where targets is not []
             select BuildRequest.Create(node.ProjectInstance, [.. targets])).ToArray();
@@ -151,6 +141,7 @@ where targets is not []
         }
 
         logger.LogDebug("Design-time build completed in {Time}s.", stopwatch.Elapsed.TotalSeconds.ToString("0.0"));
+        logger.Log(MessageDescriptor.LoadedProjects, projectGraph.Graph.ProjectNodes.Count, projectLoadingStopwatch.Elapsed.TotalSeconds);
 
         ProcessBuildResults(buildResults, logger, out var fileItems, out var staticWebAssetManifests);
 

src/Dotnet.Watch/Watch/Build/LoadedProjectGraph.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics;
 using Microsoft.Build.Evaluation;
 using Microsoft.Build.Graph;
 using Microsoft.Extensions.Logging;
@@ -9,21 +10,28 @@ namespace Microsoft.DotNet.Watch
 {
     internal sealed class LoadedProjectGraph(ProjectGraph graph, ProjectCollection collection, ILogger logger)
     {
-        // full path of proj file to list of nodes representing all target frameworks of the project:
-        public readonly IReadOnlyDictionary<string, IReadOnlyList<ProjectGraphNode>> Map = 
-            graph.ProjectNodes.GroupBy(n => n.ProjectInstance.FullPath).ToDictionary(
+        // full path of proj file to list of nodes representing all target frameworks of the project (excluding outer build nodes):
+        private readonly IReadOnlyDictionary<string, IReadOnlyList<ProjectGraphNode>> _innerBuildNodes = 
+            graph.ProjectNodes.Where(n => n.ProjectInstance.GetTargetFramework() != "").GroupBy(n => n.ProjectInstance.FullPath).ToDictionary(
                 keySelector: static g => g.Key,
                 elementSelector: static g => (IReadOnlyList<ProjectGraphNode>)[.. g]);
 
+        private readonly Lazy<IReadOnlySet<string>> _lazyBuildFiles = new(() =>
+            graph.ProjectNodes.SelectMany(p => p.ProjectInstance.ImportPaths)
+                .Concat(graph.ProjectNodes.Select(p => p.ProjectInstance.FullPath))
+                .ToHashSet(PathUtilities.OSSpecificPathComparer));
+
         public ProjectGraph Graph => graph;
         public ILogger Logger => logger;
         public ProjectCollection ProjectCollection => collection;
 
+        public IReadOnlySet<string> BuildFiles => _lazyBuildFiles.Value;
+
         public IReadOnlyList<ProjectGraphNode> GetProjectNodes(string projectPath)
         {
-            if (Map.TryGetValue(projectPath, out var rootProjectNodes))
+            if (_innerBuildNodes.TryGetValue(projectPath, out var nodes))
             {
-                return rootProjectNodes;
+                return nodes;
             }
 
             logger.LogError("Project '{ProjectPath}' not found in the project graph.", projectPath);
@@ -52,7 +60,7 @@ public IReadOnlyList<ProjectGraphNode> GetProjectNodes(string projectPath)
             ProjectGraphNode? candidate = null;
             foreach (var node in projectNodes)
             {
-                if (node.ProjectInstance.GetPropertyValue("TargetFramework") == targetFramework)
+                if (node.ProjectInstance.GetTargetFramework() == targetFramework)
                 {
                     if (candidate != null)
                     {

src/Dotnet.Watch/Watch/Build/ProjectGraphFactory.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Immutable;
+using System.Diagnostics;
 using System.Reflection;
 using System.Runtime.Versioning;
 using Microsoft.Build.Evaluation;
@@ -15,7 +16,7 @@ namespace Microsoft.DotNet.Watch;
 
 internal sealed class ProjectGraphFactory(
     ImmutableArray<ProjectRepresentation> rootProjects,
-    string? targetFramework,
+    string? virtualProjectTargetFramework,
     ImmutableDictionary<string, string> buildProperties,
     ILogger logger)
 {
@@ -36,7 +37,7 @@ internal sealed class ProjectGraphFactory(
         useAsynchronousLogging: false,
         reuseProjectRootElementCache: true);
 
-    private readonly string _targetFramework = targetFramework ?? GetProductTargetFramework();
+    private readonly string _virtualProjectTargetFramework = virtualProjectTargetFramework ?? GetProductTargetFramework();
 
     public ILogger Logger => logger;
 
@@ -55,10 +56,14 @@ private static string GetProductTargetFramework()
         var entryPoints = rootProjects.Select(p => new ProjectGraphEntryPoint(p.ProjectGraphPath, buildProperties));
         try
         {
-            return new LoadedProjectGraph(
+            var stopwatch = Stopwatch.StartNew();
+            var graph = new LoadedProjectGraph(
                 new ProjectGraph(entryPoints, _collection, (path, globalProperties, collection) => CreateProjectInstance(path, globalProperties, collection, logger), cancellationToken),
                 _collection,
                 logger);
+
+            logger.LogDebug("Project graph loaded in {Time}s.", stopwatch.Elapsed.TotalSeconds.ToString("0.0"));
+            return graph;
         }
         catch (ProjectCreationFailedException)
         {
@@ -120,7 +125,7 @@ private ProjectInstance CreateProjectInstance(string projectPath, Dictionary<str
 
             var projectInstance = VirtualProjectBuilder.CreateProjectInstance(
                 entryPointFilePath,
-                _targetFramework,
+                _virtualProjectTargetFramework,
                 projectCollection,
                 (path, line, message) =>
                 {

src/Dotnet.Watch/Watch/Build/ProjectGraphUtilities.cs

@@ -9,16 +9,22 @@ namespace Microsoft.DotNet.Watch;
 
 internal static class ProjectGraphUtilities
 {
-    public static string GetDisplayName(this ProjectGraphNode projectNode)
-        => projectNode.ProjectInstance.GetDisplayName();
+    extension(ProjectGraphNode projectNode)
+    {
+        public string GetDisplayName()
+            => projectNode.ProjectInstance.GetDisplayName();
+
+        public bool IsRoot
+            => projectNode.ReferencingProjects.Count == 0;
+    }
 
     public static string GetDisplayName(this ProjectInstance project)
         => $"{Path.GetFileNameWithoutExtension(project.FullPath)} ({project.GetTargetFramework()})";
 
     public static string GetTargetFramework(this ProjectInstance project)
         => project.GetPropertyValue(PropertyNames.TargetFramework);
 
-    public static IEnumerable<string> GetTargetFrameworks(this ProjectInstance project)
+    public static IReadOnlyList<string> GetTargetFrameworks(this ProjectInstance project)
         => project.GetStringListPropertyValue(PropertyNames.TargetFrameworks);
 
     public static Version? GetTargetFrameworkVersion(this ProjectGraphNode projectNode)
@@ -69,13 +75,13 @@ public static bool IsAutoRestartEnabled(this ProjectGraphNode projectNode)
     public static bool AreDefaultItemsEnabled(this ProjectGraphNode projectNode)
         => projectNode.GetBooleanPropertyValue(PropertyNames.EnableDefaultItems);
 
-    public static IEnumerable<string> GetDefaultItemExcludes(this ProjectGraphNode projectNode)
+    public static IReadOnlyList<string> GetDefaultItemExcludes(this ProjectGraphNode projectNode)
         => projectNode.GetStringListPropertyValue(PropertyNames.DefaultItemExcludes);
 
-    public static IEnumerable<string> GetStringListPropertyValue(this ProjectGraphNode projectNode, string propertyName)
+    public static IReadOnlyList<string> GetStringListPropertyValue(this ProjectGraphNode projectNode, string propertyName)
         => projectNode.ProjectInstance.GetStringListPropertyValue(propertyName);
 
-    public static IEnumerable<string> GetStringListPropertyValue(this ProjectInstance project, string propertyName)
+    public static IReadOnlyList<string> GetStringListPropertyValue(this ProjectInstance project, string propertyName)
         => project.GetPropertyValue(propertyName).Split(';', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries);
 
     public static bool GetBooleanPropertyValue(this ProjectGraphNode projectNode, string propertyName, bool defaultValue = false)
@@ -87,15 +93,27 @@ public static bool GetBooleanPropertyValue(this ProjectInstance project, string
     public static bool GetBooleanMetadataValue(this ProjectItemInstance item, string metadataName, bool defaultValue = false)
         => item.GetMetadataValue(metadataName) is { Length: > 0 } value ? bool.TryParse(value, out var result) && result : defaultValue;
 
+    /// <summary>
+    /// Yields the project itself and all its ancestors, excluding outer build nodes.
+    /// </summary>
     public static IEnumerable<ProjectGraphNode> GetAncestorsAndSelf(this ProjectGraphNode project)
         => GetAncestorsAndSelf([project]);
 
+    /// <summary>
+    /// Yields the given projects and all their ancestors, excluding outer build nodes.
+    /// </summary>
     public static IEnumerable<ProjectGraphNode> GetAncestorsAndSelf(this IEnumerable<ProjectGraphNode> projects)
         => GetTransitiveProjects(projects, static project => project.ReferencingProjects);
 
+    /// <summary>
+    /// Yields the project itself and all transitively referenced projects, excluding outer build nodes.
+    /// </summary>
     public static IEnumerable<ProjectGraphNode> GetDescendantsAndSelf(this ProjectGraphNode project)
         => GetDescendantsAndSelf([project]);
 
+    /// <summary>
+    /// Yields the given projects and all transitively referenced projects, excluding outer build nodes.
+    /// </summary>
     public static IEnumerable<ProjectGraphNode> GetDescendantsAndSelf(this IEnumerable<ProjectGraphNode> projects)
         => GetTransitiveProjects(projects, static project => project.ProjectReferences);
 
@@ -113,7 +131,10 @@ private static IEnumerable<ProjectGraphNode> GetTransitiveProjects(IEnumerable<P
             var project = queue.Dequeue();
             if (visited.Add(project))
             {
-                yield return project;
+                if (project.ProjectInstance.GetTargetFramework() != "")
+                {
+                    yield return project;
+                }
 
                 foreach (var referencingProject in getEdges(project))
                 {

src/Dotnet.Watch/Watch/Context/DotNetWatchContext.cs

@@ -29,11 +29,6 @@ internal sealed class DotNetWatchContext : IDisposable
         /// </summary>
         public required ProjectOptions? MainProjectOptions { get; init; }
 
-        /// <summary>
-        /// Default target framework.
-        /// </summary>
-        public required string? TargetFramework { get; init; }
-
         /// <summary>
         /// Additional arguments passed to `dotnet build` when building projects.
         /// </summary>

src/Dotnet.Watch/Watch/Context/ProjectOptions.cs

@@ -14,6 +14,14 @@ internal sealed record ProjectOptions
 
     public required string WorkingDirectory { get; init; }
 
+    /// <summary>
+    /// Target framework to use to launch the project.
+    /// If the project multi-targets and <see cref="TargetFramework"/> is null
+    /// the user will be prompted for the framework in interactive mode
+    /// or an error is reported in non-interactive mode.
+    /// </summary>
+    public string? TargetFramework { get; init; }
+
     /// <summary>
     /// No value indicates that no launch profile should be used.
     /// Null value indicates that the default launch profile should be used.