Workaround for System.ValueTuple loading issue

build/Targets/Packages.props

@@ -183,7 +183,8 @@
 
     <SystemTextEncodingCodePagesVersion>4.3.0</SystemTextEncodingCodePagesVersion>
     <SystemThreadingTasksDataflowVersion>4.5.24</SystemThreadingTasksDataflowVersion>
-    <SystemValueTupleVersion>4.3.0</SystemValueTupleVersion>
+    <!-- We need SVT assembly version at least 4.0.3.0 on net47 to make F5 work - see https://github.com/dotnet/roslyn/issues/29705 -->
+    <SystemValueTupleVersion>4.5.0</SystemValueTupleVersion>
     <SystemThreadingTasksExtensionsVersion>4.3.0</SystemThreadingTasksExtensionsVersion>
     <SQLitePCLRawbundle_greenVersion>1.1.2</SQLitePCLRawbundle_greenVersion>
     <UIAComWrapperVersion>1.1.0.14</UIAComWrapperVersion>

src/VisualStudio/Setup.Dependencies/AssemblyRedirects.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using Microsoft.VisualStudio.Shell;
 using Roslyn.VisualStudio.Setup;
 
 [assembly: ProvideDependencyBindingRedirection("Microsoft.DiaSymReader.dll")]

src/VisualStudio/Setup.Dependencies/Roslyn.VisualStudio.Setup.Dependencies.ValueTuple.pkgdef

 [$RootKey$\RuntimeConfiguration\dependentAssembly\bindingRedirection\{579ACE4E-FC58-4993-9F23-EE7079F03FE9}]

src/VisualStudio/Setup.Dependencies/Roslyn.VisualStudio.Setup.Dependencies.csproj

@@ -59,4 +59,24 @@
   <ItemGroup>
     <ProjectReference Include="..\..\Setup\DevDivPackages\Debugger\DevDivPackagesDebugger_DoNotUse.csproj" />
   </ItemGroup>
+
+  <!--
+    Workaround to make Roslyn work on Dev15. Deploys System.ValueTuple 4.0.3.0 and binding redirects to override System.ValueTuple 4.0.1.0 in PrivateAssemblies.
+    
+    Roslyn binaries are compiled against net472 and netstandard2.0. They reference ValueTuple types from mscorlib.dll and netstandard.dll, respectively.
+    netstandard.dll forwards to System.ValueTuple.dll 4.0.0.0, which in turn forwards to an implementation in mscorlib.dll.
+    System.ValueTuple.dll 4.0.1.0, which ships in PrivateAssemblies, also has an implementation of ValueTuple types (it does not forward to mscorlib.dll).
+    We need to prevent this assembly from loading since that would result in two different ValueTuple types loaded by different Roslyn components.
+    
+    The binding redirects are specified manually since ProvideDependencyBindingRedirection attribute doesn't generate the right version for some reason.
+    Using System.ValueTuple.dll from Framework directory does not work since we'd need a downgrading redirect 0.0.0.0-4.0.1.0 -> 4.0.0.0, which VS doesn't apply
+    since it already has a redirect 0.0.0.0-4.0.1.0 -> 4.0.1.0.
+    
+    TODO: Remove once we move to Dev16 (https://github.com/dotnet/roslyn/issues/29705)
+  -->
+  <ItemGroup>
+    <PackageReference Include="System.ValueTuple" Version="$(SystemValueTupleVersion)" />
+    <NuGetPackageToIncludeInVsix Include="System.ValueTuple" />
+    <Content Include="Roslyn.VisualStudio.Setup.Dependencies.ValueTuple.pkgdef" IncludeInVSIX="true" />
+  </ItemGroup>
 </Project>
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