Allow Razor cohosting to work with non-Razor SDK projects (#12118)

Part of #11834

Author: davidwengier

src/Razor/src/Microsoft.VisualStudioCode.RazorExtension/Microsoft.VisualStudioCode.RazorExtension.csproj

@@ -43,8 +43,21 @@
   </ItemGroup>
 
   <ItemGroup>
-      <!-- Need to make sure ObjectPool is in the bin folder for local development scenarios -->
-      <None Include="$(PkgMicrosoft_Extensions_ObjectPool)\lib\net8.0\Microsoft.Extensions.ObjectPool.dll" CopyToOutputDirectory="PreserveNewest" Visible="false" />
+    <!-- Need to make sure ObjectPool is in the bin folder for local development scenarios -->
+    <None Include="$(PkgMicrosoft_Extensions_ObjectPool)\lib\net8.0\Microsoft.Extensions.ObjectPool.dll" CopyToOutputDirectory="PreserveNewest" Visible="false" />
+
+    <Content Include="..\rzls\Targets\**\*.*">
+      <LinkBase>Targets</LinkBase>
+      <Pack>true</Pack>
+      <PackagePath>content\Targets</PackagePath>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+
+    <Content Include=".\Targets\**\*.targets">
+      <Pack>true</Pack>
+      <PackagePath>content\Targets</PackagePath>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
   </ItemGroup>
 
   <Target Name="PackPublishContent" DependsOnTargets="Publish">

src/Razor/src/Microsoft.VisualStudioCode.RazorExtension/Targets/Microsoft.CSharpExtension.DesignTime.targets

@@ -0,0 +1,52 @@
+<!--
+***********************************************************************************************
+Microsoft.CSharpExtension.DesignTime.targets
+
+A polyfill for the real Microsoft.CSharp.DesignTime.targets file that is supplied by the .NET
+project system in Visual Studio and the C# Dev Kit extension.
+https://github.com/dotnet/project-system/blob/8ba13c7fa917b86462e0ff32a07ef3e15eb8dfa6/src/Microsoft.VisualStudio.ProjectSystem.Managed/ProjectSystem/DesignTimeTargets/Microsoft.CSharp.DesignTime.targets
+
+WARNING:  DO NOT MODIFY this file unless you are knowledgeable about MSBuild and have
+          created a backup copy.  Incorrect changes to this file will make it
+          impossible to load or build your projects from the command-line or the IDE.
+
+Copyright (c) .NET Foundation. All rights reserved.
+***********************************************************************************************
+-->
+
+<Project>
+
+  <!-- Razor cohosting support for projects that don't use the Razor SDK -->
+
+  <!--
+    If there are any .razor or .cshtml files in this project we want to do three things:
+
+      1. Add a 'RazorWithoutSdk' capability to the project so tooling can light up as necessary
+      2. Reference the Razor source generator
+      3. Add each .razor and .cshtml file to the project as an AdditionalFiles item so the source generator can see it
+  -->
+
+  <!-- .NET Framework uses a different editor in VS -->
+ <Target Name="DetectRazorOrCshtmlFiles" BeforeTargets="AssignProjectConfiguration" Condition="'$(UsingMicrosoftNETSdkRazor)' != 'true'">
+    <ItemGroup>
+      <!-- Collect all Razor and CSHTML files -->
+      <_RazorOrCshtmlFiles Include="**\*.razor;**\*.cshtml" />
+    </ItemGroup>
+
+    <!-- Add a capability to control initialization of Razor in the IDE -->
+    <ItemGroup Condition="'@(_RazorOrCshtmlFiles)' != ''">
+      <ProjectCapability Include="RazorWithoutSdk" />
+    </ItemGroup>
+
+    <!-- As a get out of jail card, we let users turn off anything impactful, but their IDE won't really work. -->
+    <ItemGroup Condition="'$(DisableAllRazorFilesAsAdditionalFiles)' != 'true' And '@(_RazorOrCshtmlFiles)' != ''">
+      <AdditionalFiles Include="@(_RazorOrCshtmlFiles)" />
+    </ItemGroup>
+
+    <ItemGroup Condition="'$(DisableAutomaticRazorSourceGeneratorReference)' != 'true' And '@(_RazorOrCshtmlFiles)' != ''">
+      <!-- Our analyzer loader will redirect DLL loads to the right place for tooling, as long as the right filename is referenced -->
+      <Analyzer Include="Microsoft.CodeAnalysis.Razor.Compiler.dll" />
+    </ItemGroup>
+  </Target>
+
+</Project>