From 7f2a64e32beb9d08cfcb5e2158605ce84a886c95 Mon Sep 17 00:00:00 2001
From: Pranav K <prkrishn@hotmail.com>
Date: Fri, 29 Jun 2018 09:41:41 -0700
Subject: [PATCH] Razor runtime compilation produces errors if running on a
 shared runtime that's rolled forward

Do not provide compilation references from runtime MVC assemblies. This avoids cases where the app is compiled
against an older MVC but running against a newer one (e.g. shared fx roll forward) resulting in compiling against multiple
versions of MVC assemblies

Fixes #7969
---
 .../MvcServiceCollectionExtensions.cs         | 23 +++++++++++++++----
 .../Controllers/HomeController.cs             |  2 +-
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/Microsoft.AspNetCore.Mvc/MvcServiceCollectionExtensions.cs b/src/Microsoft.AspNetCore.Mvc/MvcServiceCollectionExtensions.cs
index b7baee8634..037bcdd2d3 100644
--- a/src/Microsoft.AspNetCore.Mvc/MvcServiceCollectionExtensions.cs
+++ b/src/Microsoft.AspNetCore.Mvc/MvcServiceCollectionExtensions.cs
@@ -2,6 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Reflection;
 using Microsoft.AspNetCore.Mvc;
@@ -59,15 +61,15 @@ public static IMvcBuilder AddMvc(this IServiceCollection services)
         private static void AddDefaultFrameworkParts(ApplicationPartManager partManager)
         {
             var mvcTagHelpersAssembly = typeof(InputTagHelper).GetTypeInfo().Assembly;
-            if(!partManager.ApplicationParts.OfType<AssemblyPart>().Any(p => p.Assembly == mvcTagHelpersAssembly))
+            if (!partManager.ApplicationParts.OfType<AssemblyPart>().Any(p => p.Assembly == mvcTagHelpersAssembly))
             {
-                partManager.ApplicationParts.Add(new AssemblyPart(mvcTagHelpersAssembly));
+                partManager.ApplicationParts.Add(new FrameworkAssemblyPart(mvcTagHelpersAssembly));
             }
-            
+
             var mvcRazorAssembly = typeof(UrlResolutionTagHelper).GetTypeInfo().Assembly;
-            if(!partManager.ApplicationParts.OfType<AssemblyPart>().Any(p => p.Assembly == mvcRazorAssembly))
+            if (!partManager.ApplicationParts.OfType<AssemblyPart>().Any(p => p.Assembly == mvcRazorAssembly))
             {
-                partManager.ApplicationParts.Add(new AssemblyPart(mvcRazorAssembly));
+                partManager.ApplicationParts.Add(new FrameworkAssemblyPart(mvcRazorAssembly));
             }
         }
 
@@ -94,5 +96,16 @@ public static IMvcBuilder AddMvc(this IServiceCollection services, Action<MvcOpt
 
             return builder;
         }
+
+        [DebuggerDisplay("{Name}")]
+        private class FrameworkAssemblyPart : AssemblyPart, ICompilationReferencesProvider
+        {
+            public FrameworkAssemblyPart(Assembly assembly)
+                : base(assembly)
+            {
+            }
+
+            IEnumerable<string> ICompilationReferencesProvider.GetReferencePaths() => Enumerable.Empty<string>();
+        }
     }
 }
diff --git a/test/WebSites/BasicWebSite/Controllers/HomeController.cs b/test/WebSites/BasicWebSite/Controllers/HomeController.cs
index 454aca34b8..5d5fb11525 100644
--- a/test/WebSites/BasicWebSite/Controllers/HomeController.cs
+++ b/test/WebSites/BasicWebSite/Controllers/HomeController.cs
@@ -129,7 +129,7 @@ public IActionResult GetAssemblyPartData([FromServices] ApplicationPartManager a
             // Ensures that the entry assembly part is marked correctly.
             var assemblyPartMetadata = applicationPartManager
                 .ApplicationParts
-                .Where(part => part.GetType() == typeof(AssemblyPart))
+                .OfType<AssemblyPart>()
                 .Select(part => part.Name)
                 .ToArray();