Link the same IsExternalInit.cs into every project rather than copying it

Directory.Build.props

@@ -48,6 +48,7 @@
 
   <ItemGroup>
     <AdditionalFiles Include="$(MSBuildThisFileDirectory)eng\BannedSymbols.txt" />
+    <Compile Include="$(MSBuildThisFileDirectory)\src\Shared\LanguageSupport\*.cs" Link="LanguageSupport\%(Filename).%(Extension)" />
   </ItemGroup>
 
   <PropertyGroup Label="Package and Assembly Metadata">

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer.Protocol/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a net472 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a net472 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a netstandard2.0 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a net472 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Razor/src/Microsoft.VisualStudio.LanguageServerClient.Razor/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a net472 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a net472 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test.Common/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a net472 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Razor/test/Microsoft.VisualStudio.LanguageServerClient.Razor.Test/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a net472 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/IsExternalInit.cs

@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-namespace System.Runtime.CompilerServices
-{
-    // Used to compile against C# 9 in a net472 app.
-    internal class IsExternalInit
-    {
-    }
-}

src/Shared/LanguageSupport/IsExternalInit.cs

@@ -0,0 +1,20 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+#if !NET5_0_OR_GREATER
+
+using System.ComponentModel;
+
+namespace System.Runtime.CompilerServices;
+
+/// <summary>
+/// Reserved to be used by the compiler for tracking metadata.
+/// This class should not be used by developers in source code.
+/// This dummy class is required to compile records when targeting .NET Standard
+/// </summary>
+[EditorBrowsable(EditorBrowsableState.Never)]
+internal class IsExternalInit
+{
+}
+
+#endif