File-based programs live directive diagnostics

eng/Packages.props

@@ -324,6 +324,7 @@
     <PackageVersion Include="vswhere" Version="$(vswhereVersion)" />
     <PackageVersion Include="CliWrap" Version="3.8.2" />
     <PackageVersion Include="Microsoft.DotNet.DarcLib" Version="$(MicrosoftDotNetDarcLibPackageVersion)" />
+    <PackageVersion Include="Microsoft.DotNet.FileBasedPrograms" Version="$(MicrosoftDotNetFileBasedProgramsPackageVersion)" />
     <PackageVersion Include="Spectre.Console" Version="0.51.1" />
     <!--
       The version of Roslyn we build Source Generators against that are built in this

eng/Version.Details.props

@@ -45,6 +45,8 @@ This file should be imported by eng/Versions.props
     <MicrosoftDiaSymReaderPackageVersion>2.0.0</MicrosoftDiaSymReaderPackageVersion>
     <!-- dotnet/arcade-services dependencies -->
     <MicrosoftDotNetDarcLibPackageVersion>1.1.0-beta.25503.1</MicrosoftDotNetDarcLibPackageVersion>
+    <!-- dotnet/sdk dependencies -->
+    <MicrosoftDotNetFileBasedProgramsPackageVersion>10.0.200-preview.0.25556.104</MicrosoftDotNetFileBasedProgramsPackageVersion>
     <!-- dotnet/roslyn-analyzers dependencies -->
     <MicrosoftCodeAnalysisAnalyzersPackageVersion>3.11.0</MicrosoftCodeAnalysisAnalyzersPackageVersion>
     <MicrosoftCodeAnalysisAnalyzerUtilitiesPackageVersion>3.3.0</MicrosoftCodeAnalysisAnalyzerUtilitiesPackageVersion>

src/Analyzers/Core/Analyzers/AbstractCodeQualityDiagnosticAnalyzer.cs

@@ -44,15 +44,17 @@ protected static DiagnosticDescriptor CreateDescriptor(
         bool isUnnecessary,
         bool isEnabledByDefault = true,
         bool isConfigurable = true,
-        LocalizableString? description = null)
+        LocalizableString? description = null,
+        DiagnosticSeverity defaultSeverity = DiagnosticSeverity.Info,
+        string? helpLinkUri = null)
 #pragma warning disable RS0030 // Do not use banned APIs
         => new(
                 id, title, messageFormat,
                 DiagnosticCategory.CodeQuality,
-                DiagnosticSeverity.Info,
+                defaultSeverity,
                 isEnabledByDefault,
                 description,
-                helpLinkUri: DiagnosticHelper.GetHelpLinkForDiagnosticId(id),
+                helpLinkUri: helpLinkUri ?? DiagnosticHelper.GetHelpLinkForDiagnosticId(id),
                 customTags: DiagnosticCustomTags.Create(isUnnecessary, isConfigurable, isCustomConfigurable: hasAnyCodeStyleOption, enforceOnBuild));
 #pragma warning restore RS0030 // Do not use banned APIs
 }

src/EditorFeatures/Test/Diagnostics/IDEDiagnosticIDConfigurationTests.cs

@@ -81,12 +81,18 @@ private static void ValidateHelpLinkForDiagnostic(string diagnosticId, string he
             return;
         }
 
-        if (diagnosticId == "EnableGenerateDocumentationFile")
+        if (diagnosticId == FileBasedPrograms.FileLevelDirectiveDiagnosticAnalyzer.DiagnosticId)
         {
             Assert.Equal("https://github.com/dotnet/roslyn/issues/41640", helpLinkUri);
             return;
         }
 
+        if (diagnosticId == "FileBasedPrograms")
+        {
+            Assert.Equal("https://learn.microsoft.com/dotnet/csharp/language-reference/preprocessor-directives#file-based-apps", helpLinkUri);
+            return;
+        }
+
         if (helpLinkUri != $"https://learn.microsoft.com/dotnet/fundamentals/code-analysis/style-rules/{diagnosticId.ToLowerInvariant()}")
         {
             Assert.True(false, $"Invalid help link for {diagnosticId}");

src/Features/CSharp/Portable/Diagnostics/Analyzers/FileBasedPrograms/ExternalHelpers.cs

@@ -0,0 +1,22 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#if !NET
+using Roslyn.Utilities;
+
+namespace Microsoft.DotNet.FileBasedPrograms;
+
+/// <summary>Provides implementations of certain methods to the FileBasedPrograms source package.</summary>
+internal partial class ExternalHelpers
+{
+    public static partial int CombineHashCodes(int value1, int value2)
+        => Hash.Combine(value1, value2);
+
+    public static partial string GetRelativePath(string relativeTo, string path)
+        => PathUtilities.GetRelativePath(relativeTo, path);
+
+    public static partial bool IsPathFullyQualified(string path)
+        => PathUtilities.IsAbsolute(path);
+}
+#endif

src/Features/CSharp/Portable/Diagnostics/Analyzers/FileBasedPrograms/FileLevelDirectiveDiagnosticAnalyzer.cs

@@ -0,0 +1,68 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.CodeAnalysis.CodeQuality;
+using Microsoft.CodeAnalysis.CodeStyle;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.DotNet.FileBasedPrograms;
+
+namespace Microsoft.CodeAnalysis.FileBasedPrograms;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+internal sealed class FileLevelDirectiveDiagnosticAnalyzer()
+    : AbstractCodeQualityDiagnosticAnalyzer(
+        descriptors: [s_descriptor],
+        generatedCodeAnalysisFlags: GeneratedCodeAnalysisFlags.Analyze | GeneratedCodeAnalysisFlags.ReportDiagnostics)
+{
+    public const string DiagnosticId = "FileBasedPrograms";
+
+    private static readonly DiagnosticDescriptor s_descriptor = CreateDescriptor(
+                id: DiagnosticId,
+                enforceOnBuild: EnforceOnBuild.Never,
+                title: DiagnosticId,
+                messageFormat: "{0}",
+                hasAnyCodeStyleOption: false,
+                isUnnecessary: false,
+                isEnabledByDefault: true,
+                isConfigurable: false,
+                defaultSeverity: DiagnosticSeverity.Error,
+                helpLinkUri: "https://learn.microsoft.com/dotnet/csharp/language-reference/preprocessor-directives#file-based-apps");
+
+    public override DiagnosticAnalyzerCategory GetAnalyzerCategory()
+        => DiagnosticAnalyzerCategory.SyntaxTreeWithoutSemanticsAnalysis;
+
+    protected override void InitializeWorker(AnalysisContext context)
+    {
+        context.RegisterSyntaxTreeAction(context =>
+        {
+            var cancellationToken = context.CancellationToken;
+            var tree = context.Tree;
+            if (!tree.Options.Features.ContainsKey("FileBasedProgram"))
+                return;
+
+            var root = tree.GetRoot(cancellationToken);
+            if (!root.ContainsDirectives)
+                return;
+
+            // The compiler already reports an error on all the directives past the first token in the file.
+            // Therefore, the analyzer only deals with the directives on the first token.
+            //     Console.WriteLine("Hello World!");
+            //     #:property foo=bar // error CS9297: '#:' directives cannot be after first token in file
+            var diagnosticBag = DiagnosticBag.Collect(out var diagnosticsBuilder);
+            FileLevelDirectiveHelpers.FindLeadingDirectives(
+                new SourceFile(tree.FilePath, tree.GetText(cancellationToken)),
+                root.GetLeadingTrivia(),
+                diagnosticBag,
+                builder: null);
+
+            foreach (var simpleDiagnostic in diagnosticsBuilder)
+            {
+                context.ReportDiagnostic(Diagnostic.Create(
+                    s_descriptor,
+                    location: Location.Create(tree, simpleDiagnostic.Location.TextSpan),
+                    simpleDiagnostic.Message));
+            }
+        });
+    }
+}

src/Features/CSharp/Portable/ExternalAccess/Pythia/.editorconfig

@@ -0,0 +1,3 @@
+[*.cs]
+dotnet_diagnostic.RS0051.severity = none # Symbol is not part of the declared API
+dotnet_diagnostic.RS0056.severity = none # InternalAPI.txt is missing '#nullable enable', so the nullability annotations of API isn't recorded. It is recommended to enable this tracking.

src/Features/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.Features.csproj

@@ -67,7 +67,15 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Humanizer.Core" PrivateAssets="compile" />
+    <PackageReference Include="Microsoft.DotNet.FileBasedPrograms" GeneratePathProperty="true" />
+    <EmbeddedResource
+      Include="$(PkgMicrosoft_DotNet_FileBasedPrograms)\contentFiles\cs\any\FileBasedProgramsResources.resx"
+      GenerateSource="true"
+      Namespace="Microsoft.DotNet.FileBasedPrograms" />
   </ItemGroup>
+  <PropertyGroup>
+    <DefineConstants>$(DefineConstants);FILE_BASED_PROGRAMS_SOURCE_PACKAGE_GRACEFUL_EXCEPTION</DefineConstants>
+  </PropertyGroup>
   <Import Project="..\..\..\Analyzers\CSharp\Analyzers\CSharpAnalyzers.projitems" Label="Shared" />
   <Import Project="..\..\..\Analyzers\CSharp\CodeFixes\CSharpCodeFixes.projitems" Label="Shared" />
   <Import Project="..\..\..\Compilers\CSharp\CSharpAnalyzerDriver\CSharpAnalyzerDriver.projitems" Label="Shared" />

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/FileBasedPrograms/FileBasedProgramsProjectSystem.cs

@@ -193,9 +193,9 @@ public async ValueTask<bool> TryRemoveMiscellaneousDocumentAsync(DocumentUri uri
         };
     }
 
-    protected override async ValueTask OnProjectUnloadedAsync(string projectFilePath)
+    protected override ValueTask OnProjectUnloadedAsync(string projectFilePath)
     {
-        await _projectXmlProvider.UnloadCachedDiagnosticsAsync(projectFilePath);
+        return ValueTask.CompletedTask;
     }
 
     protected override async ValueTask TransitionPrimordialProjectToLoadedAsync(

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/FileBasedPrograms/VirtualProjectXmlProvider.cs

@@ -22,63 +22,9 @@ namespace Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms;
 [Export(typeof(VirtualProjectXmlProvider)), Shared]
 [method: ImportingConstructor]
 [method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
-internal class VirtualProjectXmlProvider(IDiagnosticsRefresher diagnosticRefresher, DotnetCliHelper dotnetCliHelper)
+internal class VirtualProjectXmlProvider(DotnetCliHelper dotnetCliHelper)
 {
-    private readonly SemaphoreSlim _gate = new(initialCount: 1);
-    private readonly Dictionary<string, ImmutableArray<SimpleDiagnostic>> _diagnosticsByFilePath = [];
-
-    internal async ValueTask<ImmutableArray<SimpleDiagnostic>> GetCachedDiagnosticsAsync(string path, CancellationToken cancellationToken)
-    {
-        using (await _gate.DisposableWaitAsync(cancellationToken))
-        {
-            _diagnosticsByFilePath.TryGetValue(path, out var diagnostics);
-            return diagnostics;
-        }
-    }
-
-    internal async ValueTask UnloadCachedDiagnosticsAsync(string path)
-    {
-        using (await _gate.DisposableWaitAsync(CancellationToken.None))
-        {
-            _diagnosticsByFilePath.Remove(path);
-        }
-    }
-
     internal async Task<(string VirtualProjectXml, ImmutableArray<SimpleDiagnostic> Diagnostics)?> GetVirtualProjectContentAsync(string documentFilePath, ILogger logger, CancellationToken cancellationToken)
-    {
-        var result = await GetVirtualProjectContentImplAsync(documentFilePath, logger, cancellationToken);
-        if (result is { } project)
-        {
-            using (await _gate.DisposableWaitAsync(cancellationToken))
-            {
-                _diagnosticsByFilePath.TryGetValue(documentFilePath, out var previousCachedDiagnostics);
-                _diagnosticsByFilePath[documentFilePath] = project.Diagnostics;
-
-                // check for difference, and signal to host to update if so.
-                if (previousCachedDiagnostics.IsDefault || !project.Diagnostics.SequenceEqual(previousCachedDiagnostics))
-                    diagnosticRefresher.RequestWorkspaceRefresh();
-            }
-        }
-        else
-        {
-            using (await _gate.DisposableWaitAsync(CancellationToken.None))
-            {
-                if (_diagnosticsByFilePath.TryGetValue(documentFilePath, out var diagnostics))
-                {
-                    _diagnosticsByFilePath.Remove(documentFilePath);
-                    if (!diagnostics.IsDefaultOrEmpty)
-                    {
-                        // diagnostics have changed from "non-empty" to "unloaded". refresh.
-                        diagnosticRefresher.RequestWorkspaceRefresh();
-                    }
-                }
-            }
-        }
-
-        return result;
-    }
-
-    private async Task<(string VirtualProjectXml, ImmutableArray<SimpleDiagnostic> Diagnostics)?> GetVirtualProjectContentImplAsync(string documentFilePath, ILogger logger, CancellationToken cancellationToken)
     {
         var workingDirectory = Path.GetDirectoryName(documentFilePath);
         var process = dotnetCliHelper.Run(["run-api"], workingDirectory, shouldLocalizeOutput: true, keepStandardInputOpen: true);