Upgrade Roslyn dependency to 2.0.0.

- Added C# 7 unit and functional test to validate features work end-to-end.

#6149

build/dependencies.props

@@ -8,7 +8,7 @@
     <JsonNetBsonVersion>1.0.1</JsonNetBsonVersion>
     <MoqVersion>4.6.36-alpha</MoqVersion>
     <NetStandardImplicitPackageVersion>1.6.1</NetStandardImplicitPackageVersion>
-    <RoslynVersion>1.3.0</RoslynVersion>
+    <RoslynVersion>2.0.0</RoslynVersion>
     <RuntimeFrameworkVersion>2.0.0-*</RuntimeFrameworkVersion>
     <TestSdkVersion>15.0.0</TestSdkVersion>
     <WebApiClientVersion>5.2.2</WebApiClientVersion>

src/Microsoft.AspNetCore.Mvc.Razor/RazorViewEngineOptions.cs

@@ -16,7 +16,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor
     /// </summary>
     public class RazorViewEngineOptions
     {
-        private CSharpParseOptions _parseOptions = new CSharpParseOptions(LanguageVersion.CSharp6);
+        private CSharpParseOptions _parseOptions = new CSharpParseOptions(LanguageVersion.CSharp7);
         private CSharpCompilationOptions _compilationOptions =
             new CSharpCompilationOptions(CodeAnalysis.OutputKind.DynamicallyLinkedLibrary);
         private Action<RoslynCompilationContext> _compilationCallback = c => { };

test/Microsoft.AspNetCore.Mvc.FunctionalTests/BasicTests.cs

@@ -30,6 +30,30 @@ public BasicTests(MvcTestFixture<BasicWebSite.Startup> fixture)
 
         public HttpClient Client { get; }
 
+        [Fact]
+        public async Task CanRender_CSharp7Views()
+        {
+            // Arrange
+            var expectedMediaType = MediaTypeHeaderValue.Parse("text/html; charset=utf-8");
+            var outputFile = "compiler/resources/BasicWebSite.Home.CSharp7View.html";
+            var expectedContent =
+                await ResourceFile.ReadResourceAsync(_resourcesAssembly, outputFile, sourceFile: false);
+
+            // Act
+            var response = await Client.GetAsync("Home/CSharp7View");
+            var responseContent = await response.Content.ReadAsStringAsync();
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal(expectedMediaType, response.Content.Headers.ContentType);
+
+#if GENERATE_BASELINES
+            ResourceFile.UpdateFile(_resourcesAssembly, outputFile, expectedContent, responseContent);
+#else
+            Assert.Equal(expectedContent, responseContent, ignoreLineEndingDifferences: true);
+#endif
+        }
+
         [Fact]
         public async Task CanRender_ViewComponentWithArgumentsFromController()
         {

test/Microsoft.AspNetCore.Mvc.FunctionalTests/compiler/resources/BasicWebSite.Home.CSharp7View.html

@@ -0,0 +1,19 @@
+
+        <p>
+            <strong>John Doe's</strong> favorite number is
+
+            <em>
+(double) 6.02214085774747E&#x2B;23            </em>
+        </p>
+        <p>
+            <strong>John Smith's</strong> favorite number is
+
+            <em>
+(long) 100000000000            </em>
+        </p>
+        <p>
+            <strong>Someone Nice's</strong> favorite number is
+
+            <em>
+(decimal) 1.6180339887498948482045868344            </em>
+        </p>

test/Microsoft.AspNetCore.Mvc.Razor.Test/Internal/DefaultRoslynCompilationServiceTest.cs

@@ -2,9 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.IO;
 using System.Reflection;
-using System.Text;
 using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.AspNetCore.Mvc.Razor.Compilation;
 using Microsoft.AspNetCore.Razor.Language;
@@ -19,6 +17,38 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
 {
     public class DefaultRoslynCompilationServiceTest
     {
+        [Fact]
+        public void Compile_SucceedsForCSharp7()
+        {
+            // Arrange
+            var content = @"
+public class MyTestType
+{
+    private string _name;
+
+    public string Name
+    {
+        get => _name;
+        set => _name = value ?? throw new System.ArgumentNullException(nameof(value));
+    }
+}";
+            var compilationService = GetRoslynCompilationService();
+
+            var codeDocument = RazorCodeDocument.Create(RazorSourceDocument.Create("Hello world", "test.cshtml"));
+
+            var csharpDocument = new RazorCSharpDocument()
+            {
+                GeneratedCode = content
+            };
+
+            // Act
+            var result = compilationService.Compile(codeDocument, csharpDocument);
+
+            // Assert
+            Assert.Equal("MyTestType", result.CompiledType.Name);
+            Assert.Null(result.CompilationFailures);
+        }
+
         [Fact]
         public void Compile_ReturnsCompilationResult()
         {
@@ -219,7 +249,7 @@ public void Compile_RunsCallback()
             RoslynCompilationContext usedCompilation = null;
             var options = GetOptions(c => usedCompilation = c);
             var compilationService = GetRoslynCompilationService(options: options);
-            
+
             var codeDocument = RazorCodeDocument.Create(RazorSourceDocument.Create("Hello world", "some-relative-path"));
 
             var csharpDocument = new RazorCSharpDocument()

test/Microsoft.AspNetCore.Mvc.Razor.Test/Internal/DependencyContextRazorViewEngineOptionsSetupTest.cs

@@ -99,7 +99,7 @@ public void Configure_UsesDefaultCompilationOptions()
                 });
 
             Assert.Empty(parseOptions.PreprocessorSymbolNames);
-            Assert.Equal(LanguageVersion.CSharp6, parseOptions.LanguageVersion);
+            Assert.Equal(LanguageVersion.CSharp7, parseOptions.LanguageVersion);
         }
 
         [Fact]

test/WebSites/BasicWebSite/Controllers/HomeController.cs

@@ -1,6 +1,7 @@
 // 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.Collections.Generic;
 using System.Threading.Tasks;
 using BasicWebSite.Models;
 using Microsoft.AspNetCore.Http;
@@ -16,6 +17,18 @@ public IActionResult Index()
             return View();
         }
 
+        public IActionResult CSharp7View()
+        {
+            var people = new List<(string FirstName, string LastName, object FavoriteNumber)>()
+            {
+                ("John", "Doe", 6.022_140_857_747_474e23),
+                ("John", "Smith", 100_000_000_000),
+                ("Someone", "Nice", (decimal)1.618_033_988_749_894_848_204_586_834_365_638_117_720_309_179M),
+            };
+
+            return View(people);
+        }
+
         // Keep the return type as object to ensure that we don't
         // wrap IActionResult instances into ObjectResults.
         public object PlainView()

test/WebSites/BasicWebSite/Views/Home/CSharp7View.cshtml

@@ -0,0 +1,24 @@
+@model IEnumerable<(string FirstName, string LastName, object FavoriteNumber)>
+
+    @foreach (var person in Model)
+    {
+        <p>
+            <strong>@person.FirstName @person.LastName's</strong> favorite number is
+
+            <em>
+                @switch (person.FavoriteNumber)
+                {
+                    case double doubleVal:
+                        <text>(double) @doubleVal</text>
+                        break;
+                    case long longVal:
+                        <text>(long) @longVal</text>
+                        break;
+                    case decimal longVal:
+                        <text>(decimal) @longVal</text>
+                        break;
+
+                }
+            </em>
+        </p>
+    }