Validate binding redirects

src/MSBuild/MSBuild.csproj

@@ -330,4 +330,14 @@
 
   </Target>
 
+  <UsingTask TaskName="ValidateMSBuildPackageDependencyVersions" TaskFactory="RoslynCodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll">
+    <Task>
+      <Code Source="ValidateMSBuildPackageDependencyVersions.cs" Language="cs" />
+    </Task>
+  </UsingTask>
+
+  <Target Name="ValidateMSBuildPackageDependencyVersions" BeforeTargets="AfterBuild" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" >
+    <ValidateMSBuildPackageDependencyVersions AppConfig="@(AppConfigWithTargetPath)" AssemblyPath="$(OutputPath)" />
+  </Target>
+
 </Project>

src/MSBuild/ValidateMSBuildPackageDependencyVersions.cs

@@ -0,0 +1,64 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+using System;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Xml;
+namespace MSBuild
+{
+    public class ValidateMSBuildPackageDependencyVersions : Task
+    {
+        [Required]
+        public string AppConfig { get; set; }
+        [Required]
+        public string AssemblyPath { get; set; }
+
+        // Microsoft.Build.Conversion.Core and Microsoft.Build.Engine are deprecated, but they're still used in VS for now. This project doesn't directly reference them, so they don't appear in its output directory.
+        // Microsoft.NET.StringTools uses API not available in net35, but since we need it to work for TaskHosts as well, there are simpler versions implemented for that. Ensure it's the right version.
+        // Microsoft.Activities.Build and XamlBuildTask are loaded within an AppDomain in the XamlBuildTask after having been loaded from the GAC elsewhere. See https://github.com/dotnet/msbuild/pull/856
+        private string[] assembliesToIgnore = { "Microsoft.Build.Conversion.Core", "Microsoft.NET.StringTools.net35", "Microsoft.Build.Engine", "Microsoft.Activities.Build", "XamlBuildTask" };
+
+        public override bool Execute()
+        {
+            XmlDocument doc = new XmlDocument();
+            doc.Load(AppConfig);
+            XmlNamespaceManager namespaceManager = new(doc.NameTable);
+            namespaceManager.AddNamespace("asm", "urn:schemas-microsoft-com:asm.v1");
+            bool foundSystemValueTuple = false;
+            foreach (XmlElement dependentAssemblyElement in doc.DocumentElement.SelectNodes("/configuration/runtime/asm:assemblyBinding/asm:dependentAssembly[asm:assemblyIdentity][asm:bindingRedirect]", namespaceManager))
+            {
+                string name = (dependentAssemblyElement.SelectSingleNode("asm:assemblyIdentity", namespaceManager) as XmlElement).GetAttribute("name");
+                string version = (dependentAssemblyElement.SelectSingleNode("asm:bindingRedirect", namespaceManager) as XmlElement).GetAttribute("newVersion");
+                if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(version) && !assembliesToIgnore.Contains(name, StringComparer.OrdinalIgnoreCase))
+                {
+                    string path = Path.Combine(AssemblyPath, name + ".dll");
+                    string assemblyVersion = AssemblyName.GetAssemblyName(path).Version.ToString();
+                    if (!version.Equals(assemblyVersion))
+                    {
+                        // Ensure that the binding redirect is to the GAC version, but
+                        // we still ship the version we explicitly reference to let
+                        // API consumers bind to it at runtime.
+                        // See https://github.com/dotnet/msbuild/issues/6976.
+                        if (String.Equals(name, "System.ValueTuple", StringComparison.OrdinalIgnoreCase) && String.Equals(version, "4.0.0.0") && String.Equals(assemblyVersion, "4.0.3.0"))
+                        {
+                            foundSystemValueTuple = true;
+                        }
+                        else
+                        {
+                            Log.LogError($"Binding redirect for '{name}' redirects to a different version ({version}) than MSBuild ships ({assemblyVersion}).");
+                        }
+                    }
+                }
+            }
+            if (!foundSystemValueTuple)
+            {
+                Log.LogError("Binding redirect for 'System.ValueTuple' missing.");
+            }
+            return !Log.HasLoggedErrors;
+        }
+    }
+}

src/MSBuild/app.amd64.config

@@ -54,7 +54,7 @@
         <!-- Redirects for assemblies redistributed by MSBuild (in the .vsix). -->
         <dependentAssembly>
           <assemblyIdentity name="Microsoft.Bcl.AsyncInterfaces" publicKeyToken="cc7b13ffcd2ddd51" culture="neutral" />
-          <bindingRedirect oldVersion="0.0.0.0-1.0.0.0" newVersion="1.0.0.0" />
+          <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
         </dependentAssembly>
         <dependentAssembly>
           <assemblyIdentity name="Microsoft.NET.StringTools" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />

src/MSBuild/app.config

@@ -45,7 +45,7 @@
         <!-- Redirects for assemblies redistributed by MSBuild (in the .vsix). -->
         <dependentAssembly>
           <assemblyIdentity name="Microsoft.Bcl.AsyncInterfaces" publicKeyToken="cc7b13ffcd2ddd51" culture="neutral" />
-          <bindingRedirect oldVersion="0.0.0.0-1.0.0.0" newVersion="1.0.0.0" />
+          <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
         </dependentAssembly>
         <dependentAssembly>
           <assemblyIdentity name="Microsoft.NET.StringTools" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />