Design update.

\n\nCommit migrated from c9e0d2a60f

src/Razor/Microsoft.AspNetCore.Mvc.Razor.Extensions/test/InjectTargetExtensionTest.cs

@@ -56,12 +56,14 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             target.WriteInjectProperty(context, node);
 
             // Assert
-            Assert.Equal(
+            Assert.Equal(Environment.NewLine +
+                "#nullable restore" + Environment.NewLine +
                 "#line 2 \"test-path\"" + Environment.NewLine +
                 "[global::Microsoft.AspNetCore.Mvc.Razor.Internal.RazorInjectAttribute]" + Environment.NewLine +
                 "public PropertyType<ModelType> PropertyName { get; private set; }" + Environment.NewLine + Environment.NewLine +
                 "#line default" + Environment.NewLine +
-                "#line hidden" + Environment.NewLine,
+                "#line hidden" + Environment.NewLine +
+                "#nullable disable" + Environment.NewLine,
                 context.CodeWriter.GenerateCode());
         }
     }

src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/CodeWriterExtensions.cs

@@ -616,6 +616,11 @@ namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
 
                 if (!_codeGenerationOptions.SuppressNullabilityEnforcement)
                 {
+                    var endsWithNewline = _writer.Length > 0 && _writer[_writer.Length - 1] == '\n';
+                    if (!endsWithNewline)
+                    {
+                        _writer.WriteLine();
+                    }
                     _writer.WriteLine("#nullable restore");
                 }
 

src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDesignTimeNodeWriter.cs

@@ -462,7 +462,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             // the "usings directive is unnecessary" message.
             // Looks like:
             // __o = typeof(SomeNamespace.SomeComponent);
-            using (context.CodeWriter.BuildLinePragma(node.Source.Value))
+            using (context.CodeWriter.BuildLinePragma(node.Source.Value, context))
             {
                 context.CodeWriter.Write(DesignTimeVariable);
                 context.CodeWriter.Write(" = ");

src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultRazorCodeGenerationOptions.cs

@@ -11,7 +11,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             bool designTime,
             string rootNamespace,
             bool suppressChecksum,
-            bool supressMetadataAttributes,
+            bool suppressMetadataAttributes,
             bool suppressPrimaryMethodBody,
             bool suppressNullabilityEnforcement)
         {
@@ -20,7 +20,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             DesignTime = designTime;
             RootNamespace = rootNamespace;
             SuppressChecksum = suppressChecksum;
-            SuppressMetadataAttributes = supressMetadataAttributes;
+            SuppressMetadataAttributes = suppressMetadataAttributes;
             SuppressPrimaryMethodBody = suppressPrimaryMethodBody;
             SuppressNullabilityEnforcement = suppressNullabilityEnforcement;
         }

src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorCodeGenerationOptions.cs

@@ -15,7 +15,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                 designTime: false,
                 suppressChecksum: false,
                 rootNamespace: null,
-                supressMetadataAttributes: false,
+                suppressMetadataAttributes: false,
                 suppressPrimaryMethodBody: false,
                 suppressNullabilityEnforcement: false);
         }
@@ -28,7 +28,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                 designTime: true,
                 rootNamespace: null,
                 suppressChecksum: false,
-                supressMetadataAttributes: true,
+                suppressMetadataAttributes: true,
                 suppressPrimaryMethodBody: false,
                 suppressNullabilityEnforcement: false);
         }
@@ -111,7 +111,7 @@ namespace Microsoft.AspNetCore.Razor.Language
         public virtual bool SuppressPrimaryMethodBody { get; protected set; }
 
         /// <summary>
-        /// Gets or sets a value that determines if nullability type enforcement is restored to project settings for user code.
+        /// Gets a value that determines if nullability type enforcement should be suppressed for user code.
         /// </summary>
         public virtual bool SuppressNullabilityEnforcement { get; }
     }

src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorCodeGenerationOptionsBuilder.cs

@@ -55,7 +55,7 @@ namespace Microsoft.AspNetCore.Razor.Language
         public virtual bool SuppressPrimaryMethodBody { get; set; }
 
         /// <summary>
-        /// Gets or sets a value that determines if nullability type enforcement is restored to project settings for user code.
+        /// Gets or sets a value that determines if nullability type enforcement should be suppressed for user code.
         /// </summary>
         public virtual bool SuppressNullabilityEnforcement { get; set; }
 

src/Razor/Microsoft.CodeAnalysis.Razor/src/RazorProjectEngineBuilderExtensions.cs

@@ -14,7 +14,7 @@ namespace Microsoft.CodeAnalysis.Razor
     public static class RazorProjectEngineBuilderExtensions
     {
         /// <summary>
-        /// Sets the C# language version to respect when generating code. 
+        /// Sets the C# language version to target when generating code. 
         /// </summary>
         /// <param name="builder">The <see cref="RazorProjectEngineBuilder"/>.</param>
         /// <param name="csharpLanguageVersion">The C# <see cref="LanguageVersion"/>.</param>
@@ -26,12 +26,6 @@ namespace Microsoft.CodeAnalysis.Razor
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (builder.Configuration.LanguageVersion.Major < 3)
-            {
-                // Prior to 3.0 there were no C# version specific controlled features so there's no value in setting a CSharp language version, noop.
-                return builder;
-            }
-
             var existingFeature = builder.Features.OfType<ConfigureParserForCSharpVersionFeature>().FirstOrDefault();
             if (existingFeature != null)
             {
@@ -63,8 +57,16 @@ namespace Microsoft.CodeAnalysis.Razor
                     throw new ArgumentNullException(nameof(options));
                 }
 
+                if (options.Configuration.LanguageVersion.Major < 3)
+                {
+                    // Prior to 3.0 there were no C# version specific controlled features. Suppress nullability enforcement.
+                    options.SuppressNullabilityEnforcement = true;
+                    return;
+                }
+
                 if (CSharpLanguageVersion < LanguageVersion.CSharp8)
                 {
+                    // Having nullable flags < C# 8.0 would cause compile errors.
                     options.SuppressNullabilityEnforcement = true;
                 }
                 else
@@ -73,10 +75,11 @@ namespace Microsoft.CodeAnalysis.Razor
                     // cases in tooling when the project isn't fully configured yet at which point the CSharpLanguageVersion
                     // may be Default (value 0). In those cases that C# version is equivalently "unspecified" and is up to the consumer
                     // to act in a safe manner to not cause unneeded errors for older compilers. Therefore if the version isn't
-                    // >= 8.0 (or Latest) then nullability enforcement is suppressed.
+                    // >= 8.0 (Latest has a higher value) then nullability enforcement is suppressed.
                     //
                     // Once the project finishes configuration the C# language version will be updated to reflect the effective 
-                    // language version for the project.
+                    // language version for the project by our workspace change detectors. That mechanism extracts the correlated
+                    // Roslyn project and acquires the effective C# version at that point.
                     options.SuppressNullabilityEnforcement = false;
                 }
             }

src/Razor/Microsoft.NET.Sdk.Razor/src/build/netstandard2.0/Microsoft.NET.Sdk.Razor.Compilation.targets

@@ -13,7 +13,7 @@ Copyright (c) .NET Foundation. All rights reserved.
 <Project ToolsVersion="14.0">
   <!--
   What follows in this file is based on:
-     https://github.com/dotnet/roslyn/blob/4d92b18aee99ba8b1b4770ce65133e9ca65a94fe/src/Compilers/Core/MSBuildTask/Microsoft.CSharp.Core.targets
+     https://github.com/dotnet/roslyn/blob/db4f836b97db1e7ad261e51c67cc80c6f3c28791/src/Compilers/Core/MSBuildTask/Microsoft.CSharp.Core.targets
 
   We need to keep this basically up to date, as well as track the set of modifications we've made. Try to keep the formatting
   similar to the original to reduce noise. In general try to only deviate from the CoreCompile target when we need to for
@@ -25,32 +25,45 @@ Copyright (c) .NET Foundation. All rights reserved.
   Changes:
     Name="RazorCoreCompile"
 
+    Replace Name="CoreCompile" with Name="RazorCoreCompile"
     Replace @(Compile) with @(RazorCompile)
     Replace @(_DebugSymbolsIntermediatePath) with @(_RazorDebugSymbolsIntermediatePath)
     Replace @(IntermediateAssembly) with @(RazorIntermediateAssembly)
     Replace @(ReferencePathWithRefAssemblies) with @(RazorReferencePath)
-    Remove @(_CoreCompileResourceInputs) with @(_RazorCoreCompileResourceInputs)
+    Replace @(_CoreCompileResourceInputs) with @(_RazorCoreCompileResourceInputs)
+    Replace <Csc Condition="'%(_CoreCompileResourceInputs.WithCulture)' != 'true'" with <Csc
+    Remove comment above ^
 
     Set TargetType="$(OutputType)" to TargetType="Library" - Razor is always a .dll
-
+    
+    Remove Returns="@(CscCommandLineArgs)"
+    Remove <Import Project="Microsoft.Managed.Core.targets"/>
     Remove Returns="@(CscCommandLineArgs)"
-
     Remove @(EmbeddedFiles)
     Remove $(ApplicationIcon) $(Win32Resource) $(Win32Manifest)
     Remove @(EmbeddedDocumentation) and @(EmbeddedFiles)
     Remove @(CustomAdditionalCompileInputs) and @(CustomAdditionalCompileOutputs)
     Remove @(DocFileItem)
     Remove PdbFile="$(PdbFile)"
+    Remove $(IntermediateRefAssembly)
     Remove OutputRefAssembly="@(IntermediateRefAssembly)"
     Remove MainEntryPoint="$(StartupObject)"
+    Remove winmdobj <PdbFile  ....> and comment
+    Remove RefOnly="$(ProduceOnlyReferenceAssembly)"
+    Remove Win32Icon="$(ApplicationIcon)"
+    Remove Win32Manifest="$(Win32Manifest)"
+    Remove Win32Resource="$(Win32Resource)"
+    Remove DocumentationFile="@(DocFileItem)"
 
     Remove EmbedAllSources="$(EmbedAllSources)" - not supported by our supported version of MSBuild
 
     Remove additional steps after calling CSC
 
     Add our FileWrites after the call to CSC
+    
+    Add Condition="'@(RazorCompile)'!=''" as a condition to the RazorCoreCompile target.
   -->
- <Target Name="RazorCoreCompile"
+  <Target Name="RazorCoreCompile"
           Inputs="$(MSBuildAllProjects);
                   @(RazorCompile);
                   $(AssemblyOriginatorKeyFile);
@@ -76,12 +89,6 @@ Copyright (c) .NET Foundation. All rights reserved.
       <NoWarn Condition="'$(BuildingInsideVisualStudio)' == 'true' AND '$(VisualStudioVersion)' != '' AND '$(VisualStudioVersion)' &gt; '10.0'">$(NoWarn);2008</NoWarn>
     </PropertyGroup>
 
-    <ItemGroup Condition="'$(TargetingClr2Framework)' == 'true'">
-      <ReferencePathWithRefAssemblies>
-        <EmbedInteropTypes />
-      </ReferencePathWithRefAssemblies>
-    </ItemGroup>
-
     <PropertyGroup>
       <!-- If the user has specified AppConfigForCompiler, we'll use it. If they have not, but they set UseAppConfigForCompiler,
                  then we'll use AppConfig -->
@@ -104,6 +111,12 @@ Copyright (c) .NET Foundation. All rights reserved.
       <UseSharedCompilation>true</UseSharedCompilation>
     </PropertyGroup>
 
+    <PropertyGroup>
+      <LangVersion Condition="'$(LangVersion)' == '' AND
+        (('$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(TargetFrameworkVersion)' == 'v3.0') OR
+         ('$(TargetFrameworkIdentifier)' == '.NETStandard' AND '$(TargetFrameworkVersion)' == 'v2.1'))">8.0</LangVersion>
+    </PropertyGroup>
+
     <Csc
          AdditionalLibPaths="$(AdditionalLibPaths)"
          AddModules="@(AddModules)"
@@ -120,6 +133,7 @@ Copyright (c) .NET Foundation. All rights reserved.
          DefineConstants="$(DefineConstants)"
          DelaySign="$(DelaySign)"
          DisabledWarnings="$(NoWarn)"
+         DisableSdkPath="$(DisableSdkPath)"
          EmitDebugInformation="$(DebugSymbols)"
          EnvironmentVariables="$(CscEnvironment)"
          ErrorEndLocation="$(ErrorEndLocation)"
@@ -139,6 +153,7 @@ Copyright (c) .NET Foundation. All rights reserved.
          NoLogo="$(NoLogo)"
          NoStandardLib="$(NoCompilerStandardLib)"
          NoWin32Manifest="$(NoWin32Manifest)"
+         NullableContextOptions="$(NullableContextOptions)"
          Optimize="$(Optimize)"
          Deterministic="$(Deterministic)"
          PublicSign="$(PublicSign)"

src/Razor/Microsoft.NET.Sdk.Razor/src/build/netstandard2.0/Microsoft.NET.Sdk.Razor.Component.targets

@@ -153,12 +153,6 @@ Copyright (c) .NET Foundation. All rights reserved.
       <NoWarn Condition="'$(BuildingInsideVisualStudio)' == 'true' AND '$(VisualStudioVersion)' != '' AND '$(VisualStudioVersion)' &gt; '10.0'">$(NoWarn);2008</NoWarn>
     </PropertyGroup>
 
-    <ItemGroup Condition="'$(TargetingClr2Framework)' == 'true'">
-      <ReferencePathWithRefAssemblies>
-        <EmbedInteropTypes />
-      </ReferencePathWithRefAssemblies>
-    </ItemGroup>
-
     <PropertyGroup>
       <!-- If the user has specified AppConfigForCompiler, we'll use it. If they have not, but they set UseAppConfigForCompiler,
                  then we'll use AppConfig -->
@@ -181,6 +175,12 @@ Copyright (c) .NET Foundation. All rights reserved.
       <UseSharedCompilation>true</UseSharedCompilation>
     </PropertyGroup>
 
+    <PropertyGroup>
+      <LangVersion Condition="'$(LangVersion)' == '' AND
+        (('$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(TargetFrameworkVersion)' == 'v3.0') OR
+         ('$(TargetFrameworkIdentifier)' == '.NETStandard' AND '$(TargetFrameworkVersion)' == 'v2.1'))">8.0</LangVersion>
+    </PropertyGroup>
+
     <Csc
          AdditionalLibPaths="$(AdditionalLibPaths)"
          AddModules="@(AddModules)"
@@ -211,12 +211,12 @@ Copyright (c) .NET Foundation. All rights reserved.
          KeyFile="$(KeyOriginatorFile)"
          LangVersion="$(LangVersion)"
          LinkResources="@(LinkResource)"
-         MainEntryPoint="$(StartupObject)"
          ModuleAssemblyName="$(ModuleAssemblyName)"
          NoConfig="true"
          NoLogo="$(NoLogo)"
          NoStandardLib="$(NoCompilerStandardLib)"
          NoWin32Manifest="$(NoWin32Manifest)"
+         NullableContextOptions="$(NullableContextOptions)"
          Optimize="$(Optimize)"
          Deterministic="$(Deterministic)"
          PublicSign="$(PublicSign)"

src/Razor/Microsoft.NET.Sdk.Razor/test/IntegrationTests/BuildIntegrationTest.cs

@@ -647,6 +647,37 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
             Assert.FileDoesNotExist(result, IntermediateOutputPath, "SimpleMvc.Views.dll");
         }
 
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task Build_CSharp8_NullableEnforcement_WarningsDuringBuild_BuildServer()
+        {
+            var result = await DotnetMSBuild(
+                "Build",
+                "/p:LangVersion=8.0 /p:NullableContextOptions=enable");
+            var indexFilePath = Path.Combine(RazorIntermediateOutputPath, "Views", "Home", "Index.cshtml.g.cs");
+
+            Assert.BuildPassed(result, allowWarnings: true);
+            Assert.BuildWarning(result, "CS8618", "Models\\ErrorViewModel.cs(5,18)");
+            Assert.FileContainsLine(result, indexFilePath, "#nullable restore");
+            Assert.FileContainsLine(result, indexFilePath, "#nullable disable");
+        }
+
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task Build_CSharp8_NullableEnforcement_WarningsDuringBuild_NoBuildServer()
+        {
+            var result = await DotnetMSBuild(
+                "Build",
+                "/p:LangVersion=8.0 /p:NullableContextOptions=enable",
+                suppressBuildServer: true);
+            var indexFilePath = Path.Combine(RazorIntermediateOutputPath, "Views", "Home", "Index.cshtml.g.cs");
+
+            Assert.BuildPassed(result, allowWarnings: true);
+            Assert.BuildWarning(result, "CS8618", "Models\\ErrorViewModel.cs(5,18)");
+            Assert.FileContainsLine(result, indexFilePath, "#nullable restore");
+            Assert.FileContainsLine(result, indexFilePath, "#nullable disable");
+        }
+
         [Fact]
         [InitializeTestProject("SimpleMvc")]
         public async Task Build_Mvc_WithoutAddRazorSupportForMvc()

src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common/Language/IntegrationTests/IntegrationTestBase.cs

@@ -65,7 +65,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
         /// <summary>
         /// Gets the parse options applied when using <see cref="AddCSharpSyntaxTree(string, string)"/>.
         /// </summary>
-        protected virtual CSharpParseOptions CSharpParseOptions { get; } = new CSharpParseOptions(LanguageVersion.Latest);
+        protected virtual CSharpParseOptions CSharpParseOptions { get; } = new CSharpParseOptions(LanguageVersion.Preview);
 
         /// <summary>
         /// Gets the compilation options applied when compiling assemblies.
@@ -323,6 +323,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
                 }
 
                 b.Features.Add(new DefaultTypeNameFeature());
+                b.SetCSharpLanguageVersion(CSharpParseOptions.LanguageVersion);
 
                 // Decorate each import feature so we can normalize line endings.
                 foreach (var feature in b.Features.OfType<IImportProjectFeature>().ToArray())

src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common/Language/IntegrationTests/RazorIntegrationTestBase.cs

@@ -52,7 +52,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
                 referenceAssemblies,
                 new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));
 
-            CSharpParseOptions = new CSharpParseOptions(LanguageVersion.CSharp7_3);
+            CSharpParseOptions = new CSharpParseOptions(LanguageVersion.Preview);
         }
 
         public RazorIntegrationTestBase()
@@ -129,6 +129,8 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
                     References = references,
                 });
 
+                b.SetCSharpLanguageVersion(CSharpParseOptions.LanguageVersion);
+
                 CompilerFeatures.Register(b);
             });
         }