Add analyzer redirecting API

src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerFileReference.cs

@@ -106,6 +106,9 @@ public bool Equals(AnalyzerReference? other)
         public override int GetHashCode()
             => Hash.Combine(RuntimeHelpers.GetHashCode(_assemblyLoader), FullPath.GetHashCode());
 
+        public override string ToString()
+            => $"{nameof(AnalyzerFileReference)}({nameof(FullPath)} = {FullPath})";
+
         public override ImmutableArray<DiagnosticAnalyzer> GetAnalyzersForAllLanguages()
         {
             // This API returns duplicates of analyzers that support multiple languages.

src/Compilers/Core/Portable/PublicAPI.Unshipped.txt

@@ -17,6 +17,7 @@ Microsoft.CodeAnalysis.IPropertySymbol.PartialImplementationPart.get -> Microsof
 Microsoft.CodeAnalysis.IPropertySymbol.IsPartialDefinition.get -> bool
 Microsoft.CodeAnalysis.ITypeParameterSymbol.AllowsRefLikeType.get -> bool
 Microsoft.CodeAnalysis.RuntimeCapability.ByRefLikeGenerics = 8 -> Microsoft.CodeAnalysis.RuntimeCapability
+override Microsoft.CodeAnalysis.Diagnostics.AnalyzerFileReference.ToString() -> string!
 static Microsoft.CodeAnalysis.GeneratorExtensions.AsIncrementalGenerator(this Microsoft.CodeAnalysis.ISourceGenerator! sourceGenerator) -> Microsoft.CodeAnalysis.IIncrementalGenerator!
 static Microsoft.CodeAnalysis.GeneratorExtensions.GetGeneratorType(this Microsoft.CodeAnalysis.IIncrementalGenerator! generator) -> System.Type!
 Microsoft.CodeAnalysis.Compilation.CreatePreprocessingSymbol(string! name) -> Microsoft.CodeAnalysis.IPreprocessingSymbol!

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/LanguageServerWorkspaceFactory.cs

@@ -43,7 +43,8 @@ public LanguageServerWorkspaceFactory(
         var razorSourceGenerator = serverConfigurationFactory?.ServerConfiguration?.RazorSourceGenerator;
         ProjectSystemHostInfo = new ProjectSystemHostInfo(
             DynamicFileInfoProviders: [.. dynamicFileInfoProviders],
-            new HostDiagnosticAnalyzerProvider(razorSourceGenerator));
+            new HostDiagnosticAnalyzerProvider(razorSourceGenerator),
+            AnalyzerAssemblyRedirectors: []);
 
         TargetFrameworkManager = projectTargetFrameworkManager;
     }

src/VisualStudio/Core/Def/ProjectSystem/VisualStudioProjectFactory.cs

@@ -12,6 +12,7 @@
 using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Host.Mef;
+using Microsoft.CodeAnalysis.Workspaces.AnalyzerRedirecting;
 using Microsoft.CodeAnalysis.Workspaces.ProjectSystem;
 using Microsoft.VisualStudio.LanguageServices.ExternalAccess.VSTypeScript.Api;
 using Microsoft.VisualStudio.LanguageServices.Implementation.Diagnostics;
@@ -33,6 +34,7 @@ internal sealed class VisualStudioProjectFactory : IVsTypeScriptVisualStudioProj
     private readonly VisualStudioWorkspaceImpl _visualStudioWorkspaceImpl;
     private readonly ImmutableArray<Lazy<IDynamicFileInfoProvider, FileExtensionsMetadata>> _dynamicFileInfoProviders;
     private readonly IVisualStudioDiagnosticAnalyzerProviderFactory _vsixAnalyzerProviderFactory;
+    private readonly ImmutableArray<IAnalyzerAssemblyRedirector> _analyzerAssemblyRedirectors;
     private readonly IVsService<SVsSolution, IVsSolution2> _solution2;
 
     [ImportingConstructor]
@@ -42,12 +44,14 @@ public VisualStudioProjectFactory(
         VisualStudioWorkspaceImpl visualStudioWorkspaceImpl,
         [ImportMany] IEnumerable<Lazy<IDynamicFileInfoProvider, FileExtensionsMetadata>> fileInfoProviders,
         IVisualStudioDiagnosticAnalyzerProviderFactory vsixAnalyzerProviderFactory,
+        [ImportMany] IEnumerable<IAnalyzerAssemblyRedirector> analyzerAssemblyRedirectors,
         IVsService<SVsSolution, IVsSolution2> solution2)
     {
         _threadingContext = threadingContext;
         _visualStudioWorkspaceImpl = visualStudioWorkspaceImpl;
         _dynamicFileInfoProviders = fileInfoProviders.AsImmutableOrEmpty();
         _vsixAnalyzerProviderFactory = vsixAnalyzerProviderFactory;
+        _analyzerAssemblyRedirectors = analyzerAssemblyRedirectors.AsImmutableOrEmpty();
         _solution2 = solution2;
     }
 
@@ -93,7 +97,7 @@ public async Task<ProjectSystemProject> CreateAndAddToWorkspaceAsync(
         _visualStudioWorkspaceImpl.ProjectSystemProjectFactory.SolutionPath = solutionFilePath;
         _visualStudioWorkspaceImpl.ProjectSystemProjectFactory.SolutionTelemetryId = GetSolutionSessionId();
 
-        var hostInfo = new ProjectSystemHostInfo(_dynamicFileInfoProviders, vsixAnalyzerProvider);
+        var hostInfo = new ProjectSystemHostInfo(_dynamicFileInfoProviders, vsixAnalyzerProvider, _analyzerAssemblyRedirectors);
         var project = await _visualStudioWorkspaceImpl.ProjectSystemProjectFactory.CreateAndAddToWorkspaceAsync(projectSystemName, language, creationInfo, hostInfo);
 
         _visualStudioWorkspaceImpl.AddProjectToInternalMaps(project, creationInfo.Hierarchy, creationInfo.ProjectGuid, projectSystemName);

src/VisualStudio/Core/Test/ProjectSystemShim/VisualStudioProjectTests/AnalyzerReferenceTests.vb

@@ -2,13 +2,13 @@
 ' The .NET Foundation licenses this file to you under the MIT license.
 ' See the LICENSE file in the project root for more information.
 
-Imports System.Collections.Immutable
+Imports System.ComponentModel.Composition
 Imports System.IO
 Imports System.Threading
 Imports Microsoft.CodeAnalysis
-Imports Microsoft.CodeAnalysis.Diagnostics
-Imports Microsoft.CodeAnalysis.[Shared].TestHooks
+Imports Microsoft.CodeAnalysis.Host.Mef
 Imports Microsoft.CodeAnalysis.Test.Utilities
+Imports Microsoft.CodeAnalysis.Workspaces.AnalyzerRedirecting
 Imports Microsoft.VisualStudio.LanguageServices.Implementation.Diagnostics
 Imports Microsoft.VisualStudio.LanguageServices.UnitTests.Diagnostics
 Imports Microsoft.VisualStudio.LanguageServices.UnitTests.ProjectSystemShim.Framework
@@ -285,5 +285,43 @@ Namespace Microsoft.VisualStudio.LanguageServices.UnitTests.ProjectSystemShim
                 Assert.False(project.HasSdkCodeStyleAnalyzers)
             End Using
         End Function
+
+        <WpfFact>
+        Public Async Function RedirectedAnalyzers_CSharp() As Task
+            Using environment = New TestEnvironment(GetType(Redirector))
+                Dim project = Await environment.ProjectFactory.CreateAndAddToWorkspaceAsync(
+                    "Project", LanguageNames.CSharp, CancellationToken.None)
+
+                ' Add analyzers
+                project.AddAnalyzerReference(Path.Combine(TempRoot.Root, "Sdks", "Microsoft.NET.Sdk", "analyzers", "Microsoft.CodeAnalysis.NetAnalyzers.dll"))
+                project.AddAnalyzerReference(Path.Combine(TempRoot.Root, "Sdks", "Microsoft.NET.Sdk", "analyzers", "Microsoft.CodeAnalysis.CSharp.NetAnalyzers.dll"))
+                project.AddAnalyzerReference(Path.Combine(TempRoot.Root, "Dir", "File.dll"))
+
+                ' Ensure the SDK ones are redirected
+                AssertEx.Equal(
+                {
+                    Path.Combine(TempRoot.Root, "Sdks", "Microsoft.NET.Sdk", "analyzers", "Microsoft.CodeAnalysis.NetAnalyzers.redirected.dll"),
+                    Path.Combine(TempRoot.Root, "Sdks", "Microsoft.NET.Sdk", "analyzers", "Microsoft.CodeAnalysis.CSharp.NetAnalyzers.redirected.dll"),
+                    Path.Combine(TempRoot.Root, "Dir", "File.dll")
+                }, environment.Workspace.CurrentSolution.Projects.Single().AnalyzerReferences.Select(Function(r) r.FullPath))
+            End Using
+        End Function
+
+        <Export(GetType(IAnalyzerAssemblyRedirector))>
+        Private Class Redirector
+            Implements IAnalyzerAssemblyRedirector
+
+            <ImportingConstructor, Obsolete(MefConstruction.ImportingConstructorMessage, True)>
+            Public Sub New()
+            End Sub
+
+            Public Function RedirectPath(fullPath As String) As String Implements IAnalyzerAssemblyRedirector.RedirectPath
+                If fullPath.Contains("Microsoft.NET.Sdk") Then
+                    Return Path.ChangeExtension(fullPath, ".redirected.dll")
+                End If
+
+                Return Nothing
+            End Function
+        End Class
     End Class
 End Namespace

src/Workspaces/Core/Portable/Microsoft.CodeAnalysis.Workspaces.csproj

@@ -146,6 +146,7 @@
     <RestrictedInternalsVisibleTo Include="Microsoft.VisualStudio.IntelliCode" Partner="Pythia" Key="$(IntelliCodeKey)" />
     <RestrictedInternalsVisibleTo Include="Microsoft.VisualStudio.IntelliCode.CSharp" Partner="Pythia" Key="$(IntelliCodeCSharpKey)" />
     <RestrictedInternalsVisibleTo Include="Microsoft.VisualStudio.IntelliCode.CSharp.Extraction" Partner="Pythia" Key="$(IntelliCodeCSharpKey)" />
+    <RestrictedInternalsVisibleTo Include="Microsoft.Net.Sdk.AnalyzerRedirecting" Namespace="Microsoft.CodeAnalysis.Workspaces.AnalyzerRedirecting" />
   </ItemGroup>
   <ItemGroup>
     <!-- TODO: Remove the below IVTs to CodeStyle Unit test projects once all analyzer/code fix tests are switched to Microsoft.CodeAnalysis.Testing -->

src/Workspaces/Core/Portable/Workspace/ProjectSystem/IAnalyzerAssemblyRedirector.cs

@@ -0,0 +1,33 @@
+// 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.
+
+namespace Microsoft.CodeAnalysis.Workspaces.AnalyzerRedirecting;
+
+/// <summary>
+/// Any MEF component implementing this interface will be used to redirect analyzer assemblies.
+/// </summary>
+/// <remarks>
+/// The redirected path is passed to the compiler where it is processed in the standard way,
+/// e.g., the redirected assembly is shadow copied before it's loaded
+/// (this could be improved in the future since shadow copying redirected assemblies is usually unnecessary).
+/// </remarks>
+internal interface IAnalyzerAssemblyRedirector
+{
+    /// <param name="fullPath">
+    /// Original full path of the analyzer assembly.
+    /// </param>
+    /// <returns>
+    /// The redirected full path of the analyzer assembly
+    /// or <see langword="null"/> if this instance cannot redirect the given assembly.
+    /// </returns>
+    /// <remarks>
+    /// <para>
+    /// If two redirectors return different paths for the same assembly, no redirection will be performed.
+    /// </para>
+    /// <para>
+    /// No thread switching inside this method is allowed.
+    /// </para>
+    /// </remarks>
+    string? RedirectPath(string fullPath);
+}

src/Workspaces/Core/Portable/Workspace/ProjectSystem/ProjectSystemProject.cs

@@ -14,6 +14,7 @@
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Collections;
 using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.ErrorReporting;
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Internal.Log;
 using Microsoft.CodeAnalysis.PooledObjects;
@@ -1126,9 +1127,43 @@ private OneOrMany<string> GetMappedAnalyzerPaths(string fullPath)
             return GetMappedRazorSourceGenerator(fullPath);
         }
 
+        if (TryRedirectAnalyzerAssembly(fullPath) is { } redirectedPath)
+        {
+            return OneOrMany.Create(redirectedPath);
+        }
+
         return OneOrMany.Create(fullPath);
     }
 
+    private string? TryRedirectAnalyzerAssembly(string fullPath)
+    {
+        string? redirectedPath = null;
+
+        foreach (var redirector in _hostInfo.AnalyzerAssemblyRedirectors)
+        {
+            try
+            {
+                if (redirector.RedirectPath(fullPath) is { } currentlyRedirectedPath)
+                {
+                    if (redirectedPath == null)
+                    {
+                        redirectedPath = currentlyRedirectedPath;
+                    }
+                    else if (redirectedPath != currentlyRedirectedPath)
+                    {
+                        throw new InvalidOperationException($"Multiple redirectors disagree on the path to redirect '{fullPath}' to ('{redirectedPath}' vs '{currentlyRedirectedPath}').");
+                    }
+                }
+            }
+            catch (Exception ex) when (FatalError.ReportAndCatch(ex, ErrorSeverity.General))
+            {
+                // Ignore if the external redirector throws.
+            }
+        }
+
+        return redirectedPath;
+    }
+
     private static readonly string s_csharpCodeStyleAnalyzerSdkDirectory = CreateDirectoryPathFragment("Sdks", "Microsoft.NET.Sdk", "codestyle", "cs");
     private static readonly string s_visualBasicCodeStyleAnalyzerSdkDirectory = CreateDirectoryPathFragment("Sdks", "Microsoft.NET.Sdk", "codestyle", "vb");
 

src/Workspaces/Core/Portable/Workspace/ProjectSystem/ProjectSystemProjectHostInfo.cs

@@ -6,9 +6,11 @@
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Host.Mef;
+using Microsoft.CodeAnalysis.Workspaces.AnalyzerRedirecting;
 
 namespace Microsoft.CodeAnalysis.Workspaces.ProjectSystem;
 
 internal record ProjectSystemHostInfo(
     ImmutableArray<Lazy<IDynamicFileInfoProvider, FileExtensionsMetadata>> DynamicFileInfoProviders,
-    IHostDiagnosticAnalyzerProvider HostDiagnosticAnalyzerProvider);
+    IHostDiagnosticAnalyzerProvider HostDiagnosticAnalyzerProvider,
+    ImmutableArray<IAnalyzerAssemblyRedirector> AnalyzerAssemblyRedirectors);