Add code actions

.editorconfig

@@ -0,0 +1,11 @@
+root = true
+
+[*]
+indent_style = space
+
+[*.{csproj,vbproj,vcxproj,vcxproj.filters,proj,projitems,shproj,props,targets,ruleset,config,nuspec,resx,vsixmanifest,vsct}]
+indent_size = 2
+
+[*.{cs,csx,vb,vbx}]
+indent_size = 4
+insert_final_newline = true

.globalconfig

@@ -1,2 +1,5 @@
-# CA2025: Do not pass 'IDisposable' instances into unawaited tasks
+# CA2016: Forward the 'CancellationToken' parameter to methods
+dotnet_diagnostic.CA2016.severity = warning
+
+# CA2025: Do not pass 'IDisposable' instances into unawaited tasks
 dotnet_diagnostic.CA2025.severity = suggestion

Directory.Build.props

@@ -10,6 +10,12 @@
     <CompressionEnabled>false</CompressionEnabled>
     <LangVersion>preview</LangVersion>
 
+    <!--
+        Needed to get diagnostics inside XML doc comments.
+    -->
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    <NoWarn>$(NoWarn);1573;1591;0419</NoWarn>
+
     <!--
       Cannot trim because we dynamically execute programs
       which might depend on methods unreferenced at compile time.

Directory.Packages.props

@@ -24,6 +24,7 @@
     <PackageVersion Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" Version="$(AspNetCoreVersion)" />
     <PackageVersion Include="Microsoft.AspNetCore.Components.WebAssembly.Server" Version="$(AspNetCoreVersion)" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="$(RoslynVersion)" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.CodeStyle" Version="$(RoslynVersion)" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.Features" Version="$(RoslynVersion)" />
     <PackageVersion Include="Microsoft.DotNet.Arcade.Sdk" Version="9.0.0-beta.24372.7" />
     <PackageVersion Include="Microsoft.Extensions.Logging" Version="$(NetCoreVersion)" />
@@ -42,5 +43,6 @@
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.1" />
     <!-- Pinned transitive dependencies -->
     <PackageVersion Include="System.Data.SqlClient" Version="4.9.0" />
+    <PackageVersion Include="Microsoft.Bcl.AsyncInterfaces" Version="$(NetCoreVersion)" />
   </ItemGroup>
 </Project>

DotNetLab.slnx

@@ -8,6 +8,7 @@
     <Project Path="src/Compiler/Compiler.csproj" />
     <Project Path="src/RazorAccess/RazorAccess.csproj" />
     <Project Path="src/RoslynAccess/RoslynAccess.csproj" />
+    <Project Path="src/RoslynCodeStyleAccess/RoslynCodeStyleAccess.csproj" />
     <Project Path="src/RoslynWorkspaceAccess/RoslynWorkspaceAccess.csproj" />
     <Project Path="src/Server/Server.csproj" />
     <Project Path="src/Shared/Shared.csproj" />
@@ -18,6 +19,7 @@
     <Project Path="test/UnitTests/UnitTests.csproj" />
   </Folder>
   <Folder Name="/_/">
+    <File Path=".editorconfig" />
     <File Path=".gitignore" />
     <File Path=".globalconfig" />
     <File Path="Directory.Build.props" />

README.md

@@ -16,7 +16,7 @@ C# and Razor compiler playground in the browser via Blazor WebAssembly. https://
 - Offline support (PWA).
 - VSCode Monaco Editor.
 - Multiple input sources (especially useful for interlinked Razor components).
-- C# Language Services (completions, live diagnostics).
+- C# Language Services (completions, live diagnostics, code fixes).
 - Configuring any C# options (e.g., LangVersion, Features, OptimizationLevel, AllowUnsafe).
 
 ## Development
@@ -33,6 +33,7 @@ To hit breakpoints, it is recommended to turn off the worker (in app settings).
   which does not depend on Roslyn/Razor from elsewhere (e.g., `Shared.csproj`).
 - `src/RazorAccess`: `internal` access to Razor DLLs (via fake assembly name).
 - `src/RoslynAccess`: `internal` access to Roslyn Compiler DLLs (via fake assembly name).
+- `src/RoslynCodeStyleAccess`: `internal` access to Roslyn CodeStyle DLLs (via fake assembly name).
 - `src/RoslynWorkspaceAccess`: `internal` access to Roslyn Workspace DLLs (via fake assembly name).
 - `src/Server`: a Blazor Server entrypoint for easier development of the App
   (it has better tooling support for hot reload and debugging).

eng/CopyDotNetDTs.targets

@@ -1,14 +1,14 @@
 <Project>
 
-	<ItemGroup>
-		<Content Remove="**\*.d.ts" />
-	</ItemGroup>
+  <ItemGroup>
+    <Content Remove="**\*.d.ts" />
+  </ItemGroup>
 
-	<Target Name="CopyDotNetDTs" AfterTargets="ProcessFrameworkReferences">
-		<ItemGroup>
-			<_DotnetDTsPath Include="%(RuntimePack.PackageDirectory)\runtimes\browser-wasm\native\dotnet.d.ts" Condition="'%(RuntimePack.Identity)' == 'Microsoft.NETCore.App.Runtime.Mono.browser-wasm'" />
-		</ItemGroup>
-		<Copy SourceFiles="@(_DotnetDTsPath)" DestinationFolder="$(MSBuildProjectDirectory)\wwwroot" />
-	</Target>
+  <Target Name="CopyDotNetDTs" AfterTargets="ProcessFrameworkReferences">
+    <ItemGroup>
+      <_DotnetDTsPath Include="%(RuntimePack.PackageDirectory)\runtimes\browser-wasm\native\dotnet.d.ts" Condition="'%(RuntimePack.Identity)' == 'Microsoft.NETCore.App.Runtime.Mono.browser-wasm'" />
+    </ItemGroup>
+    <Copy SourceFiles="@(_DotnetDTsPath)" DestinationFolder="$(MSBuildProjectDirectory)\wwwroot" />
+  </Target>
 
 </Project>

src/App/App.csproj

@@ -1,58 +1,58 @@
 <Project Sdk="Microsoft.NET.Sdk.BlazorWebAssembly">
 
-	<PropertyGroup>
-		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-		<ServiceWorkerAssetsManifest>service-worker-assets.js</ServiceWorkerAssetsManifest>
-	</PropertyGroup>
-
-	<ItemGroup>
-		<PackageReference Include="Blazored.LocalStorage" />
-		<PackageReference Include="BlazorMonaco" />
-		<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" />
-		<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" PrivateAssets="all" />
-		<PackageReference Include="Microsoft.FluentUI.AspNetCore.Components" />
-		<PackageReference Include="Microsoft.FluentUI.AspNetCore.Components.Icons" />
-		<PackageReference Include="Microsoft.Net.Compilers.Razor.Toolset">
-			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-			<PrivateAssets>all</PrivateAssets>
-		</PackageReference>
-		<PackageReference Include="protobuf-net" />
-		<PackageReference Include="System.IO.Hashing" />
-	</ItemGroup>
-
-	<ItemGroup>
-		<ProjectReference Include="..\Worker\Worker.csproj" />
-	</ItemGroup>
-
-	<ItemGroup>
-		<Using Include="Microsoft.AspNetCore.Components" />
-	</ItemGroup>
-
-	<ItemGroup>
-		<ServiceWorker Include="wwwroot\service-worker.js" PublishedContent="wwwroot\service-worker.published.js" />
-	</ItemGroup>
-
-	<ItemGroup>
-		<NpmInput Include="Npm\**" Exclude="Npm\node_modules\**;Npm\package-lock.json" />
-		<NpmOutput Include="wwwroot\js\jslib.js" />
-
-		<!-- Mark as Content so it's included in `service-worker-assets.js`. -->
-		<None Remove="@(NpmOutput)" />
-		<Content Remove="@(NpmOutput)" />
-		<Content Include="@(NpmOutput)" />
-	</ItemGroup>
-
-	<Target Name="NpmBuild" BeforeTargets="PreBuildEvent" Inputs="@(NpmInput)" Outputs="@(NpmOutput)">
-		<Exec Command="npm install" WorkingDirectory="Npm" />
-		<Exec Command="npm run build" WorkingDirectory="Npm" />
-		<!--
-			Ensure the outputs are modified (even if Webpack did not touch them
-			because the input changes were irrelevant to build output)
-			so this target does not re-run unnecessarily.
-		-->
-		<Touch Files="@(NpmOutput)" AlwaysCreate="true" />
-	</Target>
-
-	<Import Project="..\..\eng\CopyDotNetDTs.targets" />
+  <PropertyGroup>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <ServiceWorkerAssetsManifest>service-worker-assets.js</ServiceWorkerAssetsManifest>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Blazored.LocalStorage" />
+    <PackageReference Include="BlazorMonaco" />
+    <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" />
+    <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.FluentUI.AspNetCore.Components" />
+    <PackageReference Include="Microsoft.FluentUI.AspNetCore.Components.Icons" />
+    <PackageReference Include="Microsoft.Net.Compilers.Razor.Toolset">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="protobuf-net" />
+    <PackageReference Include="System.IO.Hashing" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Worker\Worker.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Microsoft.AspNetCore.Components" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ServiceWorker Include="wwwroot\service-worker.js" PublishedContent="wwwroot\service-worker.published.js" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <NpmInput Include="Npm\**" Exclude="Npm\node_modules\**;Npm\package-lock.json" />
+    <NpmOutput Include="wwwroot\js\jslib.js" />
+
+    <!-- Mark as Content so it's included in `service-worker-assets.js`. -->
+    <None Remove="@(NpmOutput)" />
+    <Content Remove="@(NpmOutput)" />
+    <Content Include="@(NpmOutput)" />
+  </ItemGroup>
+
+  <Target Name="NpmBuild" BeforeTargets="PreBuildEvent" Inputs="@(NpmInput)" Outputs="@(NpmOutput)">
+    <Exec Command="npm install" WorkingDirectory="Npm" />
+    <Exec Command="npm run build" WorkingDirectory="Npm" />
+    <!--
+      Ensure the outputs are modified (even if Webpack did not touch them
+      because the input changes were irrelevant to build output)
+      so this target does not re-run unnecessarily.
+    -->
+    <Touch Files="@(NpmOutput)" AlwaysCreate="true" />
+  </Target>
+
+  <Import Project="..\..\eng\CopyDotNetDTs.targets" />
 
 </Project>

src/App/Lab/LanguageServicesClient.cs

@@ -14,10 +14,11 @@ internal sealed class LanguageServicesClient(
     BlazorMonacoInterop blazorMonacoInterop)
 {
     private Dictionary<string, string> modelUrlToFileName = [];
-    private IDisposable? completionProvider, semanticTokensProvider;
+    private IDisposable? completionProvider, semanticTokensProvider, codeActionProvider;
     private string? currentModelUrl;
     private DebounceInfo completionDebounce = new(new CancellationTokenSource());
     private DebounceInfo diagnosticsDebounce = new(new CancellationTokenSource());
+    private (string ModelUri, string? RangeJson, Task<string?> Result)? lastCodeActions;
 
     public bool Enabled => completionProvider != null;
 
@@ -87,7 +88,7 @@ private async Task RegisterAsync()
         }
 
         var cSharpLanguageSelector = new LanguageSelector("csharp");
-        completionProvider = await blazorMonacoInterop.RegisterCompletionProviderAsync(cSharpLanguageSelector, new(loggerFactory.CreateLogger<CompletionItemProviderAsync>())
+        completionProvider = await blazorMonacoInterop.RegisterCompletionProviderAsync(cSharpLanguageSelector, new(loggerFactory)
         {
             TriggerCharacters = [" ", "(", "=", "#", ".", "<", "[", "{", "\"", "/", ":", ">", "~"],
             ProvideCompletionItemsFunc = (modelUri, position, context, cancellationToken) =>
@@ -96,29 +97,35 @@ private async Task RegisterAsync()
                     ref completionDebounce,
                     (worker, modelUri, position, context),
                     """{"suggestions":[],"isIncomplete":true}""",
-                    static (args, cancellationToken) => args.worker.ProvideCompletionItemsAsync(args.modelUri, args.position, args.context),
+                    static (args, cancellationToken) => args.worker.ProvideCompletionItemsAsync(args.modelUri, args.position, args.context, cancellationToken),
                     cancellationToken);
             },
-            ResolveCompletionItemFunc = (completionItem, cancellationToken) => worker.ResolveCompletionItemAsync(completionItem),
+            ResolveCompletionItemFunc = worker.ResolveCompletionItemAsync,
         });
 
-        semanticTokensProvider = await blazorMonacoInterop.RegisterSemanticTokensProviderAsync(cSharpLanguageSelector, new SemanticTokensProvider
+        semanticTokensProvider = await blazorMonacoInterop.RegisterSemanticTokensProviderAsync(cSharpLanguageSelector, new(loggerFactory)
         {
             Legend = new SemanticTokensLegend
             {
                 TokenTypes = SemanticTokensUtil.TokenTypes.LspValues,
                 TokenModifiers = SemanticTokensUtil.TokenModifiers.LspValues,
             },
-            ProvideSemanticTokens = (modelUri, rangeJson, debug, cancellationToken) =>
+            ProvideSemanticTokens = worker.ProvideSemanticTokensAsync,
+        });
+
+        codeActionProvider = await blazorMonacoInterop.RegisterCodeActionProviderAsync(cSharpLanguageSelector, new(loggerFactory)
+        {
+            ProvideCodeActions = (modelUri, rangeJson, cancellationToken) =>
             {
-                return DebounceAsync(
-                    ref diagnosticsDebounce,
-                    (worker, modelUri, debug, rangeJson),
-                    // Fallback value when cancelled is `null` which causes an exception to be thrown
-                    // instead of returning empty tokens which would cause the semantic colorization to disappear.
-                    null,
-                    static (args, cancellationToken) => args.worker.ProvideSemanticTokensAsync(args.modelUri, args.rangeJson, args.debug),
-                    cancellationToken);
+                if (lastCodeActions is { } cached &&
+                    cached.ModelUri == modelUri && cached.RangeJson == rangeJson)
+                {
+                    return cached.Result;
+                }
+
+                var result = worker.ProvideCodeActionsAsync(modelUri, rangeJson, cancellationToken);
+                lastCodeActions = (modelUri, rangeJson, result);
+                return result;
             },
         });
     }
@@ -129,6 +136,14 @@ private void Unregister()
         completionProvider = null;
         semanticTokensProvider?.Dispose();
         semanticTokensProvider = null;
+        codeActionProvider?.Dispose();
+        codeActionProvider = null;
+        InvalidateCaches();
+    }
+
+    private void InvalidateCaches()
+    {
+        lastCodeActions = null;
     }
 
     public void OnDidChangeWorkspace(ImmutableArray<ModelInfo> models, bool updateDiagnostics = true)
@@ -138,6 +153,7 @@ public void OnDidChangeWorkspace(ImmutableArray<ModelInfo> models, bool updateDi
             return;
         }
 
+        InvalidateCaches();
         modelUrlToFileName = models.ToDictionary(m => m.Uri, m => m.FileName);
         worker.OnDidChangeWorkspace(models);
 
@@ -166,6 +182,7 @@ public void OnDidChangeModelContent(ModelContentChangedEvent args)
             return;
         }
 
+        InvalidateCaches();
         worker.OnDidChangeModelContent(args);
         UpdateDiagnostics();
     }