aspnetcore/modules/Razor

commit 5b28c06d6453696e98fb7bf32abe3aef09a5c26b
Author: Ryan Nowak <[email protected]>
Date:   Fri Feb 2 17:41:14 2018 -0800

    Add prelimianry support for extensions to Razor (#2012)
    
    * Add prelimianry support for extensions to Razor
    
    This PR adds MSBuild insfrastructure to the SDK that can understand
    concepts we need to expose to the project, code generator and runtime
    like:
    - Language version
    - Configuration
    - Extensions (plugins)
    
    As an example of how this works, I've done the wireup for MVC. This will
    now generate assembly attributes in your application that can act as a
    source-of-truth for what should be included in runtime compilation, and
    it's all based on the project-file. This means that it can be delivered
    and configured by packages.
    
    The next step here is to implement a loader for RazorProjectEngine based
    on these primitives, and then use it in our CLI tools and MVC.
    
    The next step after that is to expose it in VS and VS4Mac through the
    project system.

diff --git a/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/Microsoft.AspNetCore.Mvc.Razor.Extensions.csproj b/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/Microsoft.AspNetCore.Mvc.Razor.Extensions.csproj
index 37eafe0684a..401d07c0308 100644
--- a/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/Microsoft.AspNetCore.Mvc.Razor.Extensions.csproj
+++ b/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/Microsoft.AspNetCore.Mvc.Razor.Extensions.csproj
@@ -12,6 +12,11 @@
     </Compile>
   </ItemGroup>
 
+  <ItemGroup>
+    <Content Include="build\**\*.props" PackagePath="build\" />
+    <Content Include="build\**\*.targets" PackagePath="build\" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="../Microsoft.AspNetCore.Razor.Language/Microsoft.AspNetCore.Razor.Language.csproj" />
     <ProjectReference Include="../Microsoft.CodeAnalysis.Razor/Microsoft.CodeAnalysis.Razor.csproj" />
diff --git a/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/build/netstandard2.0/Microsoft.AspNetCore.Mvc.Razor.props b/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/build/netstandard2.0/Microsoft.AspNetCore.Mvc.Razor.props
new file mode 100644
index 00000000000..8d2ac3b630a
--- /dev/null
+++ b/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/build/netstandard2.0/Microsoft.AspNetCore.Mvc.Razor.props
@@ -0,0 +1,32 @@
+<Project>
+  <!-- 
+      MSBuild support for Razor code generation that targets ASP.NET Core MVC 2.X
+
+      The properties and items here are designed to be read by CPS so they should be just simple evaluation-time values
+      and should not require targets to initialize. 
+  -->
+  <PropertyGroup>
+    <!-- 
+      Set the primary configuration supported by this pacakge as the default configuration for Razor. 
+    -->
+    <RazorDefaultConfiguration Condition="'$(RazorDefaultConfiguration)'==''">MVC-2.1</RazorDefaultConfiguration>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <!--
+      While technically the assembly in this package can provide support for the MVC-2.0 configuration, don't declare
+      it here. The IDE is hardcoded to inject 2.0 support when needed. The settings flowing through MSBuild should reflect
+      the project's runtime.
+    -->
+    <RazorConfiguration Include="MVC-2.1">
+      <Extensions>MVC-2.1;$(CustomRazorExtension)</Extensions>
+    </RazorConfiguration>
+  </ItemGroup>
+
+  <ItemGroup>
+    <RazorExtension Include="MVC-2.1">
+      <AssemblyName>Microsoft.AspNetCore.Mvc.Razor.Extensions</AssemblyName>
+      <AssemblyFilePath>$(MSBuildThisFileDirectory)..\..\lib\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.Extensions.dll</AssemblyFilePath>
+    </RazorExtension>
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/build/netstandard2.0/Microsoft.AspNetCore.Mvc.Razor.targets b/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/build/netstandard2.0/Microsoft.AspNetCore.Mvc.Razor.targets
new file mode 100644
index 00000000000..61a0e7a8dc5
--- /dev/null
+++ b/src/Microsoft.AspNetCore.Mvc.Razor.Extensions/build/netstandard2.0/Microsoft.AspNetCore.Mvc.Razor.targets
@@ -0,0 +1,9 @@
+<Project>
+  <PropertyGroup>
+
+    <!--
+      MVC will generally want to add support for runtime compilation, but only for applications. 
+    -->
+    <GenerateRazorAssemblyInfo Condition="'$(GenerateRazorAssemblyInfo)'=='' and '$(OutputType)'=='Exe'">true</GenerateRazorAssemblyInfo>
+  </PropertyGroup>
+</Project>
\ No newline at end of file
diff --git a/src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.props b/src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.props
index 6549731539e..c25a2ab1748 100644
--- a/src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.props
+++ b/src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.props
@@ -1,15 +1,29 @@
 <Project ToolsVersion="14.0" TreatAsLocalProperty="_RazorTaskFolder;_RazorTaskAssembly">
   <PropertyGroup>
     <!--
-    Used by the Web SDK if the Razor SDK can be used for compilation. This needs to live in a nuget package (not in the SDK)
-    so that it only shows up in supported versions.
+      Used by the Web SDK if the Razor SDK can be used for compilation. This needs to live in a nuget package (not in the SDK)
+      so that it only shows up in supported versions.
     -->
     <IsRazorCompilerReferenced>true</IsRazorCompilerReferenced>
 
     <!-- 
-    Location of the CodeGeneration targets. The SDK uses this to import the file ensuring deterministic import order.
+      Location of the CodeGeneration targets. The SDK uses this to import the file ensuring deterministic import order.
     -->
     <RazorCodeGenerationTargetsPath>$(MSBuildThisFileDirectory)Microsoft.AspNetCore.Razor.Design.CodeGeneration.targets</RazorCodeGenerationTargetsPath>
+
+    <!--
+      Configures the language version of Razor. Supported and default values differ depending on the version of
+      the packages in use.
+
+      Supported:
+        2.0
+        2.1
+        Latest = 2.1
+      
+      Default:
+        2.1
+    -->
+    <RazorLangVersion Condition="'$(RazorLangVersion)'==''">2.1</RazorLangVersion>
   </PropertyGroup>
 
   <PropertyGroup>
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Properties/Resources.Designer.cs b/src/Microsoft.AspNetCore.Razor.Language/Properties/Resources.Designer.cs
index 6193fcb066e..13c56c698e4 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Properties/Resources.Designer.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Properties/Resources.Designer.cs
@@ -1856,6 +1856,20 @@ namespace Microsoft.AspNetCore.Razor.Language
         internal static string FormatRazorProjectEngineMissingFeatureDependency(object p0, object p1)
             => string.Format(CultureInfo.CurrentCulture, GetString("RazorProjectEngineMissingFeatureDependency"), p0, p1);
 
+        /// <summary>
+        /// The Razor language version '{0}' is unrecognized or not supported by this version of Razor.
+        /// </summary>
+        internal static string RazorLanguageVersion_InvalidVersion
+        {
+            get => GetString("RazorLanguageVersion_InvalidVersion");
+        }
+
+        /// <summary>
+        /// The Razor language version '{0}' is unrecognized or not supported by this version of Razor.
+        /// </summary>
+        internal static string FormatRazorLanguageVersion_InvalidVersion(object p0)
+            => string.Format(CultureInfo.CurrentCulture, GetString("RazorLanguageVersion_InvalidVersion"), p0);
+
         private static string GetString(string name, params string[] formatterNames)
         {
             var value = _resourceManager.GetString(name);
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorConfiguration.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorConfiguration.cs
index 103c3fbec51..0f00751497e 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/RazorConfiguration.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/RazorConfiguration.cs
@@ -2,24 +2,58 @@
 // 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.Linq;
 
 namespace Microsoft.AspNetCore.Razor.Language
 {
     public sealed class RazorConfiguration
     {
-        public static readonly RazorConfiguration Default = new RazorConfiguration(RazorLanguageVersion.Latest, designTime: false);
+        public static readonly RazorConfiguration Default = new RazorConfiguration(
+            RazorLanguageVersion.Latest, 
+            "unnamed",
+            Array.Empty<RazorExtension>(),
+            designTime: false);
 
-        public RazorConfiguration(RazorLanguageVersion languageVersion, bool designTime)
+        // This is used only in some back-compat scenarios. We don't expose it because there's no
+        // use case for anyone else to use it.
+        internal static readonly RazorConfiguration DefaultDesignTime = new RazorConfiguration(
+            RazorLanguageVersion.Latest,
+            "unnamed",
+            Array.Empty<RazorExtension>(),
+            designTime: true);
+
+        public RazorConfiguration(
+            RazorLanguageVersion languageVersion, 
+            string configurationName,
+            IEnumerable<RazorExtension> extensions,
+            bool designTime)
         {
             if (languageVersion == null)
             {
                 throw new ArgumentNullException(nameof(languageVersion));
             }
 
+            if (configurationName == null)
+            {
+                throw new ArgumentNullException(nameof(configurationName));
+            }
+
+            if (extensions == null)
+            {
+                throw new ArgumentNullException(nameof(extensions));
+            }
+
             LanguageVersion = languageVersion;
+            ConfigurationName = configurationName;
+            Extensions = extensions.ToArray();
             DesignTime = designTime;
         }
 
+        public string ConfigurationName { get; }
+
+        public IReadOnlyList<RazorExtension> Extensions { get; }
+
         public RazorLanguageVersion LanguageVersion { get; }
 
         public bool DesignTime { get; }
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorEngine.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorEngine.cs
index 184afd70ace..a48c31893a0 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/RazorEngine.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/RazorEngine.cs
@@ -24,8 +24,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             return CreateDesignTime(configure: null);
         }
 
-        public static RazorEngine CreateDesignTime(Action<IRazorEngineBuilder> configure)
-            => CreateCore(new RazorConfiguration(RazorLanguageVersion.Latest, designTime: true), configure);
+        public static RazorEngine CreateDesignTime(Action<IRazorEngineBuilder> configure) => CreateCore(RazorConfiguration.DefaultDesignTime, configure);
 
         // Internal since RazorEngine APIs are going to be obsolete.
         internal static RazorEngine CreateCore(RazorConfiguration configuration, Action<IRazorEngineBuilder> configure)
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorExtension.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorExtension.cs
new file mode 100644
index 00000000000..feb94b0edef
--- /dev/null
+++ b/src/Microsoft.AspNetCore.Razor.Language/RazorExtension.cs
@@ -0,0 +1,10 @@
+// Copyright(c) .NET Foundation.All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Razor.Language
+{
+    public abstract class RazorExtension
+    {
+        public abstract string ExtensionName { get; }
+    }
+}
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorLanguageVersion.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorLanguageVersion.cs
index 721c84ff00e..c2002908782 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/RazorLanguageVersion.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/RazorLanguageVersion.cs
@@ -2,10 +2,12 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics;
 
 namespace Microsoft.AspNetCore.Razor.Language
 {
-    public sealed class RazorLanguageVersion : IEquatable<RazorLanguageVersion>
+    [DebuggerDisplay("{" + nameof(DebuggerToString) + "(),nq}")]
+    public sealed class RazorLanguageVersion : IEquatable<RazorLanguageVersion>, IComparable<RazorLanguageVersion>
     {
         public static readonly RazorLanguageVersion Version_1_0 = new RazorLanguageVersion(1, 0);
 
@@ -17,6 +19,60 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public static readonly RazorLanguageVersion Latest = Version_2_1;
 
+        public static bool TryParse(string languageVersion, out RazorLanguageVersion version)
+        {
+            if (languageVersion == null)
+            {
+                throw new ArgumentNullException(nameof(languageVersion));
+            }
+
+            if (string.Equals(languageVersion, "latest", StringComparison.OrdinalIgnoreCase))
+            {
+                version = Version_2_1;
+                return true;
+            }
+            else if (languageVersion == "2.1")
+            {
+                version = Version_2_1;
+                return true; 
+            }
+            else if (languageVersion == "2.0")
+            {
+                version = Version_2_0;
+                return true;
+            }
+            else if (languageVersion == "1.1")
+            {
+                version = Version_1_1;
+                return true;
+            }
+            else if (languageVersion == "1.0")
+            {
+                version = Version_1_0;
+                return true;
+            }
+
+            version = null;
+            return false;
+        }
+
+        public static RazorLanguageVersion Parse(string languageVersion)
+        {
+            if (languageVersion == null)
+            {
+                throw new ArgumentNullException(nameof(languageVersion));
+            }
+
+            if (TryParse(languageVersion, out var parsed))
+            {
+                return parsed;
+            }
+
+            throw new ArgumentException(
+                Resources.FormatRazorLanguageVersion_InvalidVersion(languageVersion), 
+                nameof(languageVersion));
+        }
+
         // Don't want anyone else constructing language versions.
         private RazorLanguageVersion(int major, int minor)
         {
@@ -28,6 +84,22 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public int Minor { get; }
 
+        public int CompareTo(RazorLanguageVersion other)
+        {
+            if (other == null)
+            {
+                throw new ArgumentNullException(nameof(other));
+            }
+
+            var result = Major.CompareTo(other.Major);
+            if (result != 0)
+            {
+                return result;
+            }
+
+            return Minor.CompareTo(other.Minor);
+        }
+
         public bool Equals(RazorLanguageVersion other)
         {
             if (other == null)
@@ -44,7 +116,9 @@ namespace Microsoft.AspNetCore.Razor.Language
             // We don't need to do anything special for our hash code since reference equality is what we're going for.
             return base.GetHashCode();
         }
+        
+        public override string ToString() => $"{Major}.{Minor}";
 
-        public override string ToString() => $"Razor '{Major}.{Minor}'";
+        private string DebuggerToString() => $"Razor '{Major}.{Minor}'";
     }
 }
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorParserFeatureFlags.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorParserFeatureFlags.cs
index 19b1d54e80b..0629eb9af86 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/RazorParserFeatureFlags.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/RazorParserFeatureFlags.cs
@@ -9,8 +9,9 @@ namespace Microsoft.AspNetCore.Razor.Language
         {
             var allowMinimizedBooleanTagHelperAttributes = false;
 
-            if (version == RazorLanguageVersion.Version_2_1)
+            if (version.CompareTo(RazorLanguageVersion.Version_2_1) >= 0)
             {
+                // Added in 2.1
                 allowMinimizedBooleanTagHelperAttributes = true;
             }
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Resources.resx b/src/Microsoft.AspNetCore.Razor.Language/Resources.resx
index d2810420469..6413f1038b9 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Resources.resx
+++ b/src/Microsoft.AspNetCore.Razor.Language/Resources.resx
@@ -533,4 +533,7 @@ Instead, wrap the contents of the block in "{{}}":
   <data name="RazorProjectEngineMissingFeatureDependency" xml:space="preserve">
     <value>The '{0}' is missing feature '{1}'.</value>
   </data>
+  <data name="RazorLanguageVersion_InvalidVersion" xml:space="preserve">
+    <value>The Razor language version '{0}' is unrecognized or not supported by this version of Razor.</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorConfigurationNameAttribute.cs b/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorConfigurationNameAttribute.cs
new file mode 100644
index 00000000000..034e64c3093
--- /dev/null
+++ b/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorConfigurationNameAttribute.cs
@@ -0,0 +1,38 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNetCore.Razor.Hosting
+{
+    /// <summary>
+    /// Specifies the name of a Razor configuration as defined by the Razor SDK.
+    /// </summary>
+    /// <remarks>
+    /// This attribute is applied to an application's entry point assembly by the Razor SDK during the build, 
+    /// so that the Razor configuration can be loaded at runtime based on the settings provided by the project
+    /// file.
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = false, Inherited = false)]
+    public sealed class RazorConfigurationNameAttribute : Attribute
+    {
+        /// <summary>
+        /// Creates a new instance of <see cref="RazorConfigurationNameAttribute"/>.
+        /// </summary>
+        /// <param name="configurationName">The name of the Razor configuration.</param>
+        public RazorConfigurationNameAttribute(string configurationName)
+        {
+            if (configurationName == null)
+            {
+                throw new ArgumentNullException(nameof(configurationName));
+            }
+
+            ConfigurationName = configurationName;
+        }
+
+        /// <summary>
+        /// Gets the name of the Razor configuration.
+        /// </summary>
+        public string ConfigurationName { get; }
+    }
+}
\ No newline at end of file
diff --git a/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorExtensionAssemblyNameAttribute.cs b/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorExtensionAssemblyNameAttribute.cs
new file mode 100644
index 00000000000..92a9d1c6ec7
--- /dev/null
+++ b/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorExtensionAssemblyNameAttribute.cs
@@ -0,0 +1,50 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNetCore.Razor.Hosting
+{
+    /// <summary>
+    /// Specifies the name of a Razor extension as defined by the Razor SDK.
+    /// </summary>
+    /// <remarks>
+    /// This attribute is applied to an application's entry point assembly by the Razor SDK during the build, 
+    /// so that the Razor configuration can be loaded at runtime based on the settings provided by the project
+    /// file.
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true, Inherited = false)]
+    public sealed class RazorExtensionAssemblyNameAttribute : Attribute
+    {
+        /// <summary>
+        /// Creates a new instance of <see cref="RazorExtensionAssemblyNameAttribute"/>.
+        /// </summary>
+        /// <param name="extensionName">The name of the extension.</param>
+        /// <param name="assemblyName">The assembly name of the extension.</param>
+        public RazorExtensionAssemblyNameAttribute(string extensionName, string assemblyName)
+        {
+            if (extensionName == null)
+            {
+                throw new ArgumentNullException(nameof(extensionName));
+            }
+
+            if (assemblyName == null)
+            {
+                throw new ArgumentNullException(nameof(assemblyName));
+            }
+
+            ExtensionName = extensionName;
+            AssemblyName = assemblyName;
+        }
+
+        /// <summary>
+        /// Gets the assembly name of the extension.
+        /// </summary>
+        public string AssemblyName { get; }
+
+        /// <summary>
+        /// Gets the name of the extension.
+        /// </summary>
+        public string ExtensionName { get; }
+    }
+}
\ No newline at end of file
diff --git a/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorLanguageVersionAttribute.cs b/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorLanguageVersionAttribute.cs
new file mode 100644
index 00000000000..8f261143d04
--- /dev/null
+++ b/src/Microsoft.AspNetCore.Razor.Runtime/Hosting/RazorLanguageVersionAttribute.cs
@@ -0,0 +1,38 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNetCore.Razor.Hosting
+{
+    /// <summary>
+    /// Specifies the name of a Razor configuration as defined by the Razor SDK.
+    /// </summary>
+    /// <remarks>
+    /// This attribute is part of a set of metadata attributes that can be applied to an assembly at build
+    /// time by the Razor SDK. These attributes allow the Razor configuration to be loaded at runtime based 
+    /// on the settings originally provided by the project file.
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = false, Inherited = false)]
+    public sealed class RazorLanguageVersionAttribute : Attribute
+    {
+        /// <summary>
+        /// Creates a new instance of <see cref="RazorLanguageVersionAttribute"/>.
+        /// </summary>
+        /// <param name="languageVersion">The language version of Razor</param>
+        public RazorLanguageVersionAttribute(string languageVersion)
+        {
+            if (languageVersion == null)
+            {
+                throw new ArgumentNullException(nameof(languageVersion));
+            }
+
+            LanguageVersion = languageVersion;
+        }
+
+        /// <summary>
+        /// Gets the Razor language version.
+        /// </summary>
+        public string LanguageVersion { get; }
+    }
+}
\ No newline at end of file
diff --git a/src/Microsoft.NET.Sdk.Razor/build/netstandard2.0/Sdk.Razor.CurrentVersion.targets b/src/Microsoft.NET.Sdk.Razor/build/netstandard2.0/Sdk.Razor.CurrentVersion.targets
index a081f46aaf8..99109a78d4f 100644
--- a/src/Microsoft.NET.Sdk.Razor/build/netstandard2.0/Sdk.Razor.CurrentVersion.targets
+++ b/src/Microsoft.NET.Sdk.Razor/build/netstandard2.0/Sdk.Razor.CurrentVersion.targets
@@ -161,6 +161,46 @@ Copyright (c) .NET Foundation. All rights reserved.
   <Target Name="RazorCompile" DependsOnTargets="$(RazorCompileDependsOn)">
   </Target>
 
+  <!--
+    Generates assembly attributes in support for Razor runtime code generation. This is a set of standard
+    metadata attributes (defined in Microsoft.AspNetCore.Razor.Runtime) that capture the build-time
+    Razor configuration of an application to be used at runtime.
+    
+    This allows the project file to act as the source of truth for the applicable Razor configuration regardless 
+    of how Razor is used.
+
+    The SDK expects configurations that use runtime compilation to set $(GenerateRazorAssemblyInfo) to true,
+    it will be unset by default.
+  -->
+  <Target 
+    Name="RazorGetAssemblyAttributes" 
+    AfterTargets="GetAssemblyAttributes"
+    Condition="'$(GenerateRazorAssemblyInfo)'=='true' and '$(RazorDefaultConfiguration)'!=''">
+
+    <ItemGroup>
+      <_ResolvedRazorConfiguration Include="@(RazorConfiguration)" Condition="'%(RazorConfiguration.Identity)'=='$(RazorDefaultConfiguration)'" />
+      <_ResolvedRazorExtensionName Include="%(_ResolvedRazorConfiguration.Extensions)"/>
+    </ItemGroup>
+
+    <FindInList List="@(RazorExtension)" ItemSpecToFind="%(_ResolvedRazorExtensionName.Identity)">
+      <Output TaskParameter="ItemFound" ItemName="_ResolvedRazorExtension" />
+    </FindInList>
+
+    <ItemGroup>
+      <AssemblyAttribute Include="Microsoft.AspNetCore.Razor.Hosting.RazorLanguageVersionAttribute">
+        <_Parameter1>$(RazorLangVersion)</_Parameter1>
+      </AssemblyAttribute>
+      <AssemblyAttribute Include="Microsoft.AspNetCore.Razor.Hosting.RazorConfigurationNameAttribute">
+        <_Parameter1>$(RazorDefaultConfiguration)</_Parameter1>
+      </AssemblyAttribute>
+      <AssemblyAttribute Include="Microsoft.AspNetCore.Razor.Hosting.RazorExtensionAssemblyNameAttribute" Condition="'%(_ResolvedRazorExtension.AssemblyName)'!=''">
+        <_Parameter1>%(_ResolvedRazorExtension.Identity)</_Parameter1>
+        <_Parameter2>%(_ResolvedRazorExtension.AssemblyName)</_Parameter2>
+      </AssemblyAttribute>
+    </ItemGroup>
+
+  </Target>
+
   <!--
     Gathers input source files for code generation. This is a separate target so that we can avoid
     lots of work when there are no inputs for code generation.
diff --git a/src/Microsoft.VisualStudio.Editor.Razor/DefaultTemplateEngineFactoryService.cs b/src/Microsoft.VisualStudio.Editor.Razor/DefaultTemplateEngineFactoryService.cs
index a82d1b8e94c..ab5518bb463 100644
--- a/src/Microsoft.VisualStudio.Editor.Razor/DefaultTemplateEngineFactoryService.cs
+++ b/src/Microsoft.VisualStudio.Editor.Razor/DefaultTemplateEngineFactoryService.cs
@@ -43,7 +43,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
             var project = FindProject(projectPath);
             var configuration = (project?.Configuration as MvcExtensibilityConfiguration) ?? DefaultConfiguration;
             var razorLanguageVersion = configuration.LanguageVersion;
-            var razorConfiguration = new RazorConfiguration(razorLanguageVersion, designTime: true);
+            var razorConfiguration = new RazorConfiguration(razorLanguageVersion, "unnamed", Array.Empty<RazorExtension>(), designTime: true);
 
             RazorEngine engine;
             if (razorLanguageVersion.Major == 1)
diff --git a/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/Assert.cs b/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/Assert.cs
index 35cb880c1af..1cf20d0e817 100644
--- a/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/Assert.cs
+++ b/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/Assert.cs
@@ -100,6 +100,50 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
             throw new BuildOutputMissingException(result, match);
         }
 
+        public static void FileContainsLine(MSBuildResult result, string filePath, string match)
+        {
+            if (result == null)
+            {
+                throw new ArgumentNullException(nameof(result));
+            }
+
+            filePath = Path.Combine(result.Project.DirectoryPath, filePath);
+            FileExists(result, filePath);
+            
+            var lines = File.ReadAllLines(filePath);
+            for (var i = 0; i < lines.Length; i++)
+            {
+                var line = lines[i].Trim();
+                if (line == match)
+                {
+                    return;
+                }
+            }
+
+            throw new FileContentMissingException(result, filePath, File.ReadAllText(filePath), match);
+        }
+
+        public static void FileDoesNotContainLine(MSBuildResult result, string filePath, string match)
+        {
+            if (result == null)
+            {
+                throw new ArgumentNullException(nameof(result));
+            }
+
+            filePath = Path.Combine(result.Project.DirectoryPath, filePath);
+            FileExists(result, filePath);
+
+            var lines = File.ReadAllLines(filePath);
+            for (var i = 0; i < lines.Length; i++)
+            {
+                var line = lines[i].Trim();
+                if (line == match)
+                {
+                    throw new FileContentFoundException(result, filePath, File.ReadAllText(filePath), match);
+                }
+            }
+        }
+
         public static void FileExists(MSBuildResult result, params string[] paths)
         {
             if (result == null)
@@ -304,6 +348,66 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
             protected override string Heading => $"Build did not contain the line: '{Match}'.";
         }
 
+        private class FileContentFoundException : MSBuildXunitException
+        {
+            public FileContentFoundException(MSBuildResult result, string filePath, string content, string match)
+                : base(result)
+            {
+                FilePath = filePath;
+                Content = content;
+                Match = match;
+            }
+
+            public string Content { get; }
+
+            public string FilePath { get; }
+
+            public string Match { get; }
+
+            protected override string Heading
+            {
+                get
+                {
+                    var builder = new StringBuilder();
+                    builder.AppendFormat("File content of '{0}' should not contain line: '{1}'.", FilePath, Match);
+                    builder.AppendLine();
+                    builder.AppendLine();
+                    builder.AppendLine(Content);
+                    return builder.ToString();
+                }
+            }
+        }
+
+        private class FileContentMissingException : MSBuildXunitException
+        {
+            public FileContentMissingException(MSBuildResult result, string filePath, string content, string match)
+                : base(result)
+            {
+                FilePath = filePath;
+                Content = content;
+                Match = match;
+            }
+
+            public string Content { get; }
+
+            public string FilePath { get; }
+
+            public string Match { get; }
+
+            protected override string Heading
+            {
+                get
+                {
+                    var builder = new StringBuilder();
+                    builder.AppendFormat("File content of '{0}' did not contain the line: '{1}'.", FilePath, Match);
+                    builder.AppendLine();
+                    builder.AppendLine();
+                    builder.AppendLine(Content);
+                    return builder.ToString();
+                }
+            }
+        }
+
         private class FileMissingException : MSBuildXunitException
         {
             public FileMissingException(MSBuildResult result, string filePath)
diff --git a/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/ConfigurationMetadataIntegrationTest.cs b/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/ConfigurationMetadataIntegrationTest.cs
new file mode 100644
index 00000000000..f527157a89a
--- /dev/null
+++ b/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/ConfigurationMetadataIntegrationTest.cs
@@ -0,0 +1,90 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.IO;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
+{
+    public class ConfigurationMetadataIntegrationTest : MSBuildIntegrationTestBase
+    {
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task Build_WithMvc_AddsConfigurationMetadata()
+        {
+            var result = await DotnetMSBuild("Build", $"/p:RazorCompileOnBuild=true");
+
+            Assert.BuildPassed(result);
+
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.PrecompiledViews.dll");
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.PrecompiledViews.pdb");
+
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.AssemblyInfo.cs");
+            Assert.FileContainsLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "SimpleMvc.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorLanguageVersionAttribute(\"2.1\")]");
+            Assert.FileContainsLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "SimpleMvc.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorConfigurationNameAttribute(\"MVC-2.1\")]");
+            Assert.FileContainsLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "SimpleMvc.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorExtensionAssemblyNameAttribute(\"MVC-2.1\", \"Microsoft.AspNetCore.Mvc.Razor.Extensions\")]");
+        }
+
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task Build_WithGenerateRazorAssemblyInfo_False_SuppressesConfigurationMetadata()
+        {
+            var result = await DotnetMSBuild("Build", $"/p:RazorCompileOnBuild=true /p:GenerateRazorAssemblyInfo=false");
+
+            Assert.BuildPassed(result);
+
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.PrecompiledViews.dll");
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.PrecompiledViews.pdb");
+
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.AssemblyInfo.cs");
+            Assert.FileDoesNotContainLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "SimpleMvc.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorLanguageVersionAttribute(\"2.1\")]");
+            Assert.FileDoesNotContainLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "SimpleMvc.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorConfigurationNameAttribute(\"MVC-2.1\")]");
+            Assert.FileDoesNotContainLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "SimpleMvc.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorExtensionAssemblyNameAttribute(\"MVC-2.1\", \"Microsoft.AspNetCore.Razor.Extensions\")]");
+        }
+
+        [Fact]
+        [InitializeTestProject("ClassLibrary")]
+        public async Task Build_ForClassLibrary_SuppressesConfigurationMetadata()
+        {
+            var result = await DotnetMSBuild("Build", $"/p:RazorCompileOnBuild=true");
+
+            Assert.BuildPassed(result);
+
+            Assert.FileExists(result, IntermediateOutputPath, "ClassLibrary.PrecompiledViews.dll");
+            Assert.FileExists(result, IntermediateOutputPath, "ClassLibrary.PrecompiledViews.pdb");
+
+            Assert.FileExists(result, IntermediateOutputPath, "ClassLibrary.AssemblyInfo.cs");
+            Assert.FileDoesNotContainLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "ClassLibrary.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorLanguageVersionAttribute(\"2.1\")]");
+            Assert.FileDoesNotContainLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "ClassLibrary.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorConfigurationNameAttribute(\"MVC-2.1\")]");
+            Assert.FileDoesNotContainLine(
+                result,
+                Path.Combine(IntermediateOutputPath, "ClassLibrary.AssemblyInfo.cs"),
+                "[assembly: Microsoft.AspNetCore.Razor.Hosting.RazorExtensionAssemblyNameAttribute(\"MVC-2.1\", \"Microsoft.AspNetCore.Razor.Extensions\")]");
+        }
+    }
+}
diff --git a/test/testapps/AppWithP2PReference/AppWithP2PReference.csproj b/test/testapps/AppWithP2PReference/AppWithP2PReference.csproj
index ac5bb850141..2dc2432d05c 100644
--- a/test/testapps/AppWithP2PReference/AppWithP2PReference.csproj
+++ b/test/testapps/AppWithP2PReference/AppWithP2PReference.csproj
@@ -1,10 +1,13 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project>
+
+  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk.Web" />
+  
   <PropertyGroup>
     <_RazorMSBuildRoot>$(SolutionRoot)src\Microsoft.AspNetCore.Razor.Design\bin\$(Configuration)\netstandard2.0\</_RazorMSBuildRoot>
   </PropertyGroup>
-
   <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.props" />
   <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Razor.Design\build\netstandard2.0\Microsoft.AspNetCore.Razor.Design.props" />
+  <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Mvc.Razor.Extensions\build\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.props" />
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.0</TargetFramework>
@@ -18,4 +21,9 @@
   <ItemGroup>
     <ProjectReference Include="..\ClassLibrary\ClassLibrary.csproj"/>
   </ItemGroup>
+
+  <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Mvc.Razor.Extensions\build\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.targets" />
+
+  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk.Web" />
+  <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.targets" />
 </Project>
diff --git a/test/testapps/ClassLibrary/ClassLibrary.csproj b/test/testapps/ClassLibrary/ClassLibrary.csproj
index 86cb453382a..f4e970b76f5 100644
--- a/test/testapps/ClassLibrary/ClassLibrary.csproj
+++ b/test/testapps/ClassLibrary/ClassLibrary.csproj
@@ -1,10 +1,14 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project>
+
+  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk" />
+  
   <PropertyGroup>
     <_RazorMSBuildRoot>$(SolutionRoot)src\Microsoft.AspNetCore.Razor.Design\bin\$(Configuration)\netstandard2.0\</_RazorMSBuildRoot>
   </PropertyGroup>
 
   <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.props" />
   <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Razor.Design\build\netstandard2.0\Microsoft.AspNetCore.Razor.Design.props" />
+  <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Mvc.Razor.Extensions\build\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.props" />
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.0</TargetFramework>
@@ -20,4 +24,10 @@
       <Pack>false</Pack>
     </Content>
   </ItemGroup>
+
+  <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Mvc.Razor.Extensions\build\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.targets" />
+
+  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />
+  <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.targets" />
+
 </Project>
diff --git a/test/testapps/Directory.Build.targets b/test/testapps/Directory.Build.targets
index 4f2e91835cc..8c119d5413b 100644
--- a/test/testapps/Directory.Build.targets
+++ b/test/testapps/Directory.Build.targets
@@ -1,3 +1,2 @@
 <Project>
-  <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.targets" />
 </Project>
diff --git a/test/testapps/SimpleMvc/SimpleMvc.csproj b/test/testapps/SimpleMvc/SimpleMvc.csproj
index 4525726119d..d2f6e05d851 100644
--- a/test/testapps/SimpleMvc/SimpleMvc.csproj
+++ b/test/testapps/SimpleMvc/SimpleMvc.csproj
@@ -1,10 +1,14 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project>
+
+  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk.Web" />
+  
   <PropertyGroup>
     <_RazorMSBuildRoot>$(SolutionRoot)src\Microsoft.AspNetCore.Razor.Design\bin\$(Configuration)\netstandard2.0\</_RazorMSBuildRoot>
   </PropertyGroup>
 
   <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.props" />
   <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Razor.Design\build\netstandard2.0\Microsoft.AspNetCore.Razor.Design.props" />
+  <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Mvc.Razor.Extensions\build\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.props" />
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.0</TargetFramework>
@@ -15,4 +19,9 @@
 
   <!-- Test Placeholder -->
 
+  <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Mvc.Razor.Extensions\build\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.targets" />
+
+  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk.Web" />
+  <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.targets" />
+
 </Project>
diff --git a/test/testapps/SimplePages/SimplePages.csproj b/test/testapps/SimplePages/SimplePages.csproj
index 4525726119d..12865d018c4 100644
--- a/test/testapps/SimplePages/SimplePages.csproj
+++ b/test/testapps/SimplePages/SimplePages.csproj
@@ -1,10 +1,14 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project>
+
+  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk.Web" />
+  
   <PropertyGroup>
     <_RazorMSBuildRoot>$(SolutionRoot)src\Microsoft.AspNetCore.Razor.Design\bin\$(Configuration)\netstandard2.0\</_RazorMSBuildRoot>
   </PropertyGroup>
 
   <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.props" />
   <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Razor.Design\build\netstandard2.0\Microsoft.AspNetCore.Razor.Design.props" />
+  <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Mvc.Razor.Extensions\build\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.props" />
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.0</TargetFramework>
@@ -15,4 +19,9 @@
 
   <!-- Test Placeholder -->
 
+  <Import Project="$(SolutionRoot)src\Microsoft.AspNetCore.Mvc.Razor.Extensions\build\netstandard2.0\Microsoft.AspNetCore.Mvc.Razor.targets" />
+
+  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk.Web" />
+  <Import Project="$(SolutionRoot)src\Microsoft.NET.Sdk.Razor\SDK\Sdk.targets" />
+  
 </Project>