Update Semantic Search to work when ServiceHub is disabled

eng/Directory.Packages.props

@@ -181,6 +181,7 @@
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies.net472" Version="1.0.3" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies.net461" Version="1.0.3" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies.net451" Version="1.0.3" />
+    <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies.net45" Version="1.0.3" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies.net40" Version="1.0.3" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies.net20" Version="1.0.3" />
     <PackageVersion Include="System.Buffers" Version="4.5.1" />

src/Features/CSharp/Portable/SemanticSearch/CSharpSemanticSearchService.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-#if NET6_0_OR_GREATER
-
 using System;
 using System.Collections.Generic;
 using System.Composition;
@@ -48,5 +46,3 @@ internal sealed class CSharpSemanticSearchService() : AbstractSemanticSearchServ
             CSharpSemanticSearchUtilities.CompilationOptions);
     }
 }
-
-#endif

src/Features/CSharpTest/Microsoft.CodeAnalysis.CSharp.Features.UnitTests.csproj

@@ -21,7 +21,7 @@
 
     <CopyPublishedOutputProjectReference Include="..\..\Tools\SemanticSearch\ReferenceAssemblies\SemanticSearch.ReferenceAssemblies.csproj">
       <OutputItemType>SemanticSearch_RefAssemblies</OutputItemType>
-      <SetTargetFramework>TargetFramework=$(NetRoslyn)</SetTargetFramework>
+      <SetTargetFramework>TargetFramework=netstandard2.0</SetTargetFramework>
     </CopyPublishedOutputProjectReference>
   </ItemGroup>
   <ItemGroup>

src/Features/Core/Portable/FeaturesResources.resx

@@ -3240,9 +3240,6 @@ Zero-width positive lookbehind assertions are typically used at the beginning of
   <data name="Query" xml:space="preserve">
     <value>Query</value>
   </data>
-  <data name="Semantic_search_only_supported_on_net_core" xml:space="preserve">
-    <value>Semantic search is only supported when code analysis runs in a separate process on the latest .NET (see Tools > Options > Text Editor > C# > Advanced).</value>
-  </data>
   <data name="Semantic_search_query_terminated_with_exception" xml:space="preserve">
     <value>Semantic search query terminated with exception</value>
   </data>

src/Features/Core/Portable/SemanticSearch/AbstractSemanticSearchService.cs

@@ -1,42 +1,38 @@
 // 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 NET6_0_OR_GREATER
 
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.Composition;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
-using System.Linq;
 using System.Reflection;
-using System.Runtime.Loader;
 using System.Text;
-using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Classification;
-using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Emit;
 using Microsoft.CodeAnalysis.ErrorReporting;
 using Microsoft.CodeAnalysis.FindSymbols;
 using Microsoft.CodeAnalysis.FindUsages;
 using Microsoft.CodeAnalysis.Host;
-using Microsoft.CodeAnalysis.Host.Mef;
-using Microsoft.CodeAnalysis.Internal.Log;
 using Microsoft.CodeAnalysis.PooledObjects;
-using Microsoft.CodeAnalysis.Shared.Collections;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Tags;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
 
+#if NET6_0_OR_GREATER
+using System.Runtime.Loader;
+#endif
+
 namespace Microsoft.CodeAnalysis.SemanticSearch;
 
 internal abstract partial class AbstractSemanticSearchService : ISemanticSearchService
 {
+#if NET6_0_OR_GREATER
     internal sealed class LoadContext() : AssemblyLoadContext("SemanticSearchLoadContext", isCollectible: true)
     {
         private readonly AssemblyLoadContext _current = GetLoadContext(typeof(LoadContext).Assembly)!;
@@ -47,6 +43,22 @@ internal sealed class LoadContext() : AssemblyLoadContext("SemanticSearchLoadCon
         protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
             => IntPtr.Zero;
     }
+#else
+    internal sealed class LoadContext
+    {
+        [SuppressMessage("Performance", "CA1822:Mark members as static", Justification = "Signature needs to match AssemblyLoadContext")]
+        public Assembly LoadFromStream(Stream assembly, Stream? assemblySymbols)
+        {
+            return Assembly.Load(assembly.ReadAllBytes(), assemblySymbols?.ReadAllBytes());
+        }
+
+        [SuppressMessage("Performance", "CA1822:Mark members as static", Justification = "Signature needs to match AssemblyLoadContext")]
+        public void Unload()
+        {
+            // No action to take
+        }
+    }
+#endif
 
     private static readonly FindReferencesSearchOptions s_findReferencesSearchOptions = new()
     {
@@ -63,7 +75,7 @@ protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
         string referenceAssembliesDir,
         ISemanticSearchResultsObserver observer,
         OptionsProvider<ClassificationOptions> classificationOptions,
-        TraceSource traceSource,
+        TraceSource? traceSource,
         CancellationToken cancellationToken)
     {
         try
@@ -108,7 +120,7 @@ protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
                 {
                     if (diagnostic.Severity == DiagnosticSeverity.Error)
                     {
-                        traceSource.TraceInformation($"Semantic search query compilation failed: {diagnostic}");
+                        traceSource?.TraceInformation($"Semantic search query compilation failed: {diagnostic}");
                     }
                 }
 
@@ -136,7 +148,7 @@ protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
 
                 if (!TryGetFindMethod(queryAssembly, out var findMethod, out var errorMessage, out var errorMessageArgs))
                 {
-                    traceSource.TraceInformation($"Semantic search failed: {errorMessage}");
+                    traceSource?.TraceInformation($"Semantic search failed: {errorMessage}");
                     return CreateResult(errorMessage, errorMessageArgs);
                 }
 
@@ -208,7 +220,7 @@ protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
 
                         await observer.OnUserCodeExceptionAsync(new UserCodeExceptionInfo(projectDisplay, e.Message, exceptionNameTaggedText, stackTraceTaggedText, span), cancellationToken).ConfigureAwait(false);
 
-                        traceSource.TraceInformation($"Semantic query execution failed due to user code exception: {e}");
+                        traceSource?.TraceInformation($"Semantic query execution failed due to user code exception: {e}");
                         return CreateResult(FeaturesResources.Semantic_search_query_terminated_with_exception);
                     }
 
@@ -289,7 +301,7 @@ private static void FormatStackTrace(Exception e, Assembly queryAssembly, out Li
 
                 // display last StackDisplayDepthLimit frames preceding the host frame:
                 skippedFrameCount = Math.Max(0, displayFramesEnd - StackDisplayDepthLimit);
-                displayFrames = frames[skippedFrameCount..displayFramesEnd];
+                displayFrames = frames.AsSpan()[skippedFrameCount..displayFramesEnd].ToArray();
             }
             catch
             {
@@ -433,4 +445,3 @@ private static bool TryGetFindMethod(Assembly queryAssembly, [NotNullWhen(true)]
         }
     }
 }
-#endif

src/Features/Core/Portable/SemanticSearch/IRemoteSemanticSearchService.cs

@@ -8,7 +8,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Classification;
-using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.ErrorReporting;
 using Microsoft.CodeAnalysis.FindUsages;
 using Microsoft.CodeAnalysis.Host.Mef;
@@ -131,19 +130,28 @@ public async ValueTask<ClassificationOptions> GetClassificationOptionsAsync(stri
     public static async ValueTask<ExecuteQueryResult> ExecuteQueryAsync(Solution solution, string language, string query, string referenceAssembliesDir, ISemanticSearchResultsObserver results, OptionsProvider<ClassificationOptions> classificationOptions, CancellationToken cancellationToken)
     {
         var client = await RemoteHostClient.TryGetClientAsync(solution.Services, cancellationToken).ConfigureAwait(false);
-        if (client == null)
+        if (client != null)
         {
-            return new ExecuteQueryResult(FeaturesResources.Semantic_search_only_supported_on_net_core);
-        }
+            var serverCallback = new ServerCallback(solution, results, classificationOptions);
 
-        var serverCallback = new ServerCallback(solution, results, classificationOptions);
+            var result = await client.TryInvokeAsync<IRemoteSemanticSearchService, ExecuteQueryResult>(
+                solution,
+                (service, solutionInfo, callbackId, cancellationToken) => service.ExecuteQueryAsync(solutionInfo, callbackId, language, query, referenceAssembliesDir, cancellationToken),
+                callbackTarget: serverCallback,
+                cancellationToken).ConfigureAwait(false);
 
-        var result = await client.TryInvokeAsync<IRemoteSemanticSearchService, ExecuteQueryResult>(
-            solution,
-            (service, solutionInfo, callbackId, cancellationToken) => service.ExecuteQueryAsync(solutionInfo, callbackId, language, query, referenceAssembliesDir, cancellationToken),
-            callbackTarget: serverCallback,
-            cancellationToken).ConfigureAwait(false);
+            if (result.HasValue)
+            {
+                return result.Value;
+            }
+        }
 
-        return result.Value;
+        return await ExecuteQueryInCurrentProcessAsync(solution, language, query, referenceAssembliesDir, results, classificationOptions, cancellationToken).ConfigureAwait(false);
+    }
+
+    public static async ValueTask<ExecuteQueryResult> ExecuteQueryInCurrentProcessAsync(Solution solution, string language, string query, string referenceAssembliesDir, ISemanticSearchResultsObserver results, OptionsProvider<ClassificationOptions> classificationOptions, CancellationToken cancellationToken)
+    {
+        var service = solution.Services.GetLanguageServices(language).GetRequiredService<ISemanticSearchService>();
+        return await service.ExecuteQueryAsync(solution, query, referenceAssembliesDir, results, classificationOptions, traceSource: null, cancellationToken).ConfigureAwait(false);
     }
 }

src/Features/Core/Portable/SemanticSearch/ISemanticSearchService.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Diagnostics;
-using System.Runtime.Serialization;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Classification;
@@ -29,6 +28,6 @@ internal interface ISemanticSearchService : ILanguageService
         string referenceAssembliesDir,
         ISemanticSearchResultsObserver observer,
         OptionsProvider<ClassificationOptions> classificationOptions,
-        TraceSource traceSource,
+        TraceSource? traceSource,
         CancellationToken cancellationToken);
 }

src/Features/Core/Portable/SemanticSearch/SemanticSearchUtilities.cs

@@ -5,12 +5,12 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Text;
 using Microsoft.CodeAnalysis.ErrorReporting;
 using Microsoft.CodeAnalysis.Host;
-using Microsoft.CodeAnalysis.Text;
 using Microsoft.CodeAnalysis.Shared.Extensions;
-using System.Linq;
+using Microsoft.CodeAnalysis.Text;
 
 namespace Microsoft.CodeAnalysis.SemanticSearch;
 

src/Features/Core/Portable/SemanticSearch/SemanticSearchWorkspace.cs

@@ -6,8 +6,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Host;
-using Microsoft.CodeAnalysis.Options;
-using Microsoft.CodeAnalysis.SolutionCrawler;
 using Microsoft.CodeAnalysis.Text;
 
 namespace Microsoft.CodeAnalysis.SemanticSearch;