Move CSharpLanguageVersion to RazorConfiguration

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/RazorConfiguration.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Immutable;
 using System.Linq;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.Extensions.Internal;
 
 namespace Microsoft.AspNetCore.Razor.Language;
@@ -14,7 +15,8 @@ public sealed record class RazorConfiguration(
     bool UseConsolidatedMvcViews = true,
     bool SuppressAddComponentParameter = false,
     LanguageServerFlags? LanguageServerFlags = null,
-    bool UseRoslynTokenizer = false)
+    bool UseRoslynTokenizer = false,
+    LanguageVersion CSharpLanguageVersion = LanguageVersion.Default)
 {
     public static readonly RazorConfiguration Default = new(
         RazorLanguageVersion.Latest,
@@ -29,6 +31,7 @@ public sealed record class RazorConfiguration(
            LanguageServerFlags == other.LanguageServerFlags &&
            UseConsolidatedMvcViews == other.UseConsolidatedMvcViews &&
            UseRoslynTokenizer == other.UseRoslynTokenizer &&
+           CSharpLanguageVersion == other.CSharpLanguageVersion &&
            Extensions.SequenceEqual(other.Extensions);
 
     public override int GetHashCode()
@@ -41,6 +44,7 @@ public sealed record class RazorConfiguration(
         hash.Add(UseConsolidatedMvcViews);
         hash.Add(LanguageServerFlags);
         hash.Add(UseRoslynTokenizer);
+        hash.Add(CSharpLanguageVersion);
         return hash;
     }
 }

src/Razor/benchmarks/Microsoft.AspNetCore.Razor.Microbenchmarks/LanguageServer/RazorLanguageServerBenchmarkBase.cs

@@ -73,7 +73,7 @@ public class RazorLanguageServerBenchmarkBase : ProjectSnapshotManagerBenchmarkB
             {
                 updater.ProjectAdded(hostProject);
                 var tagHelpers = CommonResources.LegacyTagHelpers;
-                var projectWorkspaceState = ProjectWorkspaceState.Create(tagHelpers, CodeAnalysis.CSharp.LanguageVersion.CSharp11);
+                var projectWorkspaceState = ProjectWorkspaceState.Create(tagHelpers);
                 updater.ProjectWorkspaceStateChanged(hostProject.Key, projectWorkspaceState);
                 updater.DocumentAdded(hostProject.Key, hostDocument, textLoader);
             },

src/Razor/benchmarks/Microsoft.AspNetCore.Razor.Microbenchmarks/Resources/Telerik/Kendo.Mvc.Examples.project.razor.json

@@ -6,6 +6,7 @@
     "ConfigurationName": "MVC-3.0",
     "LanguageVersion": "7.0",
     "UseRoslynTokenizer": true,
+    "CSharpLanguageVersion": 1100,
     "Extensions": [
       "MVC-3.0"
     ]
@@ -159527,8 +159528,7 @@
           "Runtime.Name": "Components.None"
         }
       }
-    ],
-    "CSharpLanguageVersion": 1100
+    ]
   },
   "RootNamespace": "Kendo.Mvc.Examples",
   "Documents": [

src/Razor/benchmarks/Microsoft.AspNetCore.Razor.Microbenchmarks/Resources/project.razor.json

@@ -6,6 +6,7 @@
     "ConfigurationName": "MVC-3.0",
     "LanguageVersion": "3.0",
     "UseRoslynTokenizer": true,
+    "CSharpLanguageVersion": 800,
     "Extensions": [ "MVC-3.0" ]
   },
   "ProjectWorkspaceState": {
@@ -16126,8 +16127,7 @@
           "Runtime.Name": "Components.None"
         }
       }
-    ],
-    "CSharpLanguageVersion": 800
+    ]
   },
   "RootNamespace": "blazorserver",
   "Documents": [

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/ProjectSystem/RazorProjectService.cs

@@ -366,7 +366,7 @@ internal partial class RazorProjectService : IRazorProjectService, IRazorProject
 
                 if (!projectWorkspaceState.Equals(ProjectWorkspaceState.Default))
                 {
-                    _logger.LogInformation($"Updating project '{project.Key}' TagHelpers ({projectWorkspaceState.TagHelpers.Length}) and C# Language Version ({projectWorkspaceState.CSharpLanguageVersion}).");
+                    _logger.LogInformation($"Updating project '{project.Key}' TagHelpers ({projectWorkspaceState.TagHelpers.Length}).");
                 }
 
                 updater.ProjectWorkspaceStateChanged(project.Key, projectWorkspaceState);

src/Razor/src/Microsoft.AspNetCore.Razor.ProjectEngineHost/ProjectSystem/ProjectWorkspaceState.cs

@@ -5,44 +5,33 @@ using System;
 using System.Collections.Immutable;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language;
-using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.Extensions.Internal;
 
 namespace Microsoft.AspNetCore.Razor.ProjectSystem;
 
 internal sealed class ProjectWorkspaceState : IEquatable<ProjectWorkspaceState>
 {
-    public static readonly ProjectWorkspaceState Default = new(ImmutableArray<TagHelperDescriptor>.Empty, LanguageVersion.Default);
+    public static readonly ProjectWorkspaceState Default = new(ImmutableArray<TagHelperDescriptor>.Empty);
 
     public ImmutableArray<TagHelperDescriptor> TagHelpers { get; }
-    public LanguageVersion CSharpLanguageVersion { get; }
 
     private ProjectWorkspaceState(
-        ImmutableArray<TagHelperDescriptor> tagHelpers,
-        LanguageVersion csharpLanguageVersion)
+        ImmutableArray<TagHelperDescriptor> tagHelpers)
     {
         TagHelpers = tagHelpers;
-        CSharpLanguageVersion = csharpLanguageVersion;
     }
 
     public static ProjectWorkspaceState Create(
-        ImmutableArray<TagHelperDescriptor> tagHelpers,
-        LanguageVersion csharpLanguageVersion = LanguageVersion.Default)
-        => tagHelpers.IsEmpty && csharpLanguageVersion == LanguageVersion.Default
+        ImmutableArray<TagHelperDescriptor> tagHelpers)
+        => tagHelpers.IsEmpty
             ? Default
-            : new(tagHelpers, csharpLanguageVersion);
-
-    public static ProjectWorkspaceState Create(LanguageVersion csharpLanguageVersion)
-        => csharpLanguageVersion == LanguageVersion.Default
-            ? Default
-            : new(ImmutableArray<TagHelperDescriptor>.Empty, csharpLanguageVersion);
+            : new(tagHelpers);
 
     public override bool Equals(object? obj)
         => obj is ProjectWorkspaceState other && Equals(other);
 
     public bool Equals(ProjectWorkspaceState? other)
         => other is not null &&
-           CSharpLanguageVersion == other.CSharpLanguageVersion &&
            TagHelpers.SequenceEqual(other.TagHelpers);
 
     public override int GetHashCode()
@@ -50,7 +39,6 @@ internal sealed class ProjectWorkspaceState : IEquatable<ProjectWorkspaceState>
         var hash = HashCodeCombiner.Start();
 
         hash.Add(TagHelpers);
-        hash.Add(CSharpLanguageVersion);
 
         return hash.CombinedHash;
     }

src/Razor/src/Microsoft.AspNetCore.Razor.ProjectEngineHost/Serialization/MessagePack/Formatters/ProjectWorkspaceStateFormatter.cs

@@ -8,7 +8,6 @@ using Microsoft.AspNetCore.Razor.PooledObjects;
 using Microsoft.AspNetCore.Razor.ProjectSystem;
 using Microsoft.AspNetCore.Razor.Serialization.MessagePack.Formatters.TagHelpers;
 using Microsoft.AspNetCore.Razor.Utilities;
-using Microsoft.CodeAnalysis.CSharp;
 
 namespace Microsoft.AspNetCore.Razor.Serialization.MessagePack.Formatters;
 
@@ -22,7 +21,7 @@ internal sealed class ProjectWorkspaceStateFormatter : ValueFormatter<ProjectWor
 
     public override ProjectWorkspaceState Deserialize(ref MessagePackReader reader, SerializerCachingOptions options)
     {
-        reader.ReadArrayHeaderAndVerify(3);
+        reader.ReadArrayHeaderAndVerify(2);
 
         var checksums = reader.Deserialize<ImmutableArray<Checksum>>(options);
 
@@ -47,19 +46,17 @@ internal sealed class ProjectWorkspaceStateFormatter : ValueFormatter<ProjectWor
         }
 
         var tagHelpers = builder.DrainToImmutable();
-        var csharpLanguageVersion = (LanguageVersion)reader.ReadInt32();
 
-        return ProjectWorkspaceState.Create(tagHelpers, csharpLanguageVersion);
+        return ProjectWorkspaceState.Create(tagHelpers);
     }
 
     public override void Serialize(ref MessagePackWriter writer, ProjectWorkspaceState value, SerializerCachingOptions options)
     {
-        writer.WriteArrayHeader(3);
+        writer.WriteArrayHeader(2);
 
         var checksums = value.TagHelpers.SelectAsArray(x => x.Checksum);
 
         writer.Serialize(checksums, options);
         writer.Serialize(value.TagHelpers, options);
-        writer.Write((int)value.CSharpLanguageVersion);
     }
 }

src/Razor/src/Microsoft.AspNetCore.Razor.ProjectEngineHost/Serialization/MessagePack/Formatters/RazorConfigurationFormatter.cs

@@ -4,6 +4,7 @@
 using MessagePack;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.PooledObjects;
+using Microsoft.CodeAnalysis.CSharp;
 
 namespace Microsoft.AspNetCore.Razor.Serialization.MessagePack.Formatters;
 
@@ -13,7 +14,7 @@ internal sealed class RazorConfigurationFormatter : ValueFormatter<RazorConfigur
 
     // The count of properties in RazorConfiguration that are serialized. The number of Extensions will be added
     // to this, for the final serialized value count.
-    private const int SerializedPropertyCount = 5;
+    private const int SerializedPropertyCount = 6;
 
     private RazorConfigurationFormatter()
     {
@@ -29,6 +30,7 @@ internal sealed class RazorConfigurationFormatter : ValueFormatter<RazorConfigur
         var suppressAddComponentParameter = reader.ReadBoolean();
         var useConsolidatedMvcViews = reader.ReadBoolean();
         var useRoslynTokenizer = reader.ReadBoolean();
+        var csharpLanguageVersion = (LanguageVersion)reader.ReadInt32();
 
         count -= SerializedPropertyCount;
 
@@ -52,7 +54,8 @@ internal sealed class RazorConfigurationFormatter : ValueFormatter<RazorConfigur
             extensions,
             UseConsolidatedMvcViews: useConsolidatedMvcViews,
             SuppressAddComponentParameter: suppressAddComponentParameter,
-            UseRoslynTokenizer: useRoslynTokenizer);
+            UseRoslynTokenizer: useRoslynTokenizer,
+            CSharpLanguageVersion: csharpLanguageVersion);
     }
 
     public override void Serialize(ref MessagePackWriter writer, RazorConfiguration value, SerializerCachingOptions options)
@@ -77,6 +80,7 @@ internal sealed class RazorConfigurationFormatter : ValueFormatter<RazorConfigur
         writer.Write(value.SuppressAddComponentParameter);
         writer.Write(value.UseConsolidatedMvcViews);
         writer.Write(value.UseRoslynTokenizer);
+        writer.Write((int)value.CSharpLanguageVersion);
 
         count -= SerializedPropertyCount;
 

src/Razor/src/Microsoft.AspNetCore.Razor.ProjectEngineHost/Utilities/RazorProjectInfoFactory.cs

@@ -92,7 +92,7 @@ internal static class RazorProjectInfoFactory
 
         var tagHelpers = await project.GetTagHelpersAsync(engine, NoOpTelemetryReporter.Instance, cancellationToken).ConfigureAwait(false);
 
-        var projectWorkspaceState = ProjectWorkspaceState.Create(tagHelpers, csharpLanguageVersion);
+        var projectWorkspaceState = ProjectWorkspaceState.Create(tagHelpers);
 
         return new RazorProjectInfo(
             projectKey: new ProjectKey(intermediateOutputPath),

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/ProjectState.cs

@@ -152,14 +152,6 @@ internal class ProjectState
         {
             ProjectWorkspaceStateVersion = Version;
         }
-
-        if ((difference & ClearProjectWorkspaceStateVersionMask) != 0 &&
-            CSharpLanguageVersion != older.CSharpLanguageVersion)
-        {
-            // C# language version changed. This impacts the ProjectEngine, reset it.
-            _projectEngine = null;
-            ConfigurationVersion = Version;
-        }
     }
 
     // Internal set for testing.
@@ -174,7 +166,7 @@ internal class ProjectState
 
     public ImmutableArray<TagHelperDescriptor> TagHelpers => ProjectWorkspaceState.TagHelpers;
 
-    public LanguageVersion CSharpLanguageVersion => ProjectWorkspaceState.CSharpLanguageVersion;
+    public LanguageVersion CSharpLanguageVersion => HostProject.Configuration.CSharpLanguageVersion;
 
     /// <summary>
     /// Gets the version of this project, INCLUDING content changes. The <see cref="Version"/> is

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/LiveShare/Host/ProjectSnapshotManagerProxy.cs

@@ -101,7 +101,7 @@ internal class ProjectSnapshotManagerProxy : IProjectSnapshotManagerProxy, IColl
         }
 
         var tagHelpers = await project.GetTagHelpersAsync(CancellationToken.None).ConfigureAwait(false);
-        var projectWorkspaceState = ProjectWorkspaceState.Create(tagHelpers, project.CSharpLanguageVersion);
+        var projectWorkspaceState = ProjectWorkspaceState.Create(tagHelpers);
         var projectFilePath = _session.ConvertLocalPathToSharedUri(project.FilePath);
         var intermediateOutputPath = _session.ConvertLocalPathToSharedUri(project.IntermediateOutputPath);
         var projectHandleProxy = new ProjectSnapshotHandleProxy(projectFilePath, intermediateOutputPath, project.Configuration, project.RootNamespace, projectWorkspaceState);

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/ProjectWorkspaceStateGenerator.cs

@@ -294,6 +294,7 @@ internal sealed partial class ProjectWorkspaceStateGenerator(
             {
                 SuppressAddComponentParameter = suppressAddComponentParameter,
                 UseRoslynTokenizer = useRoslynTokenizer,
+                CSharpLanguageVersion = csharpLanguageVersion
             };
 
             using var _ = StopwatchPool.GetPooledObject(out var watch);
@@ -318,7 +319,7 @@ internal sealed partial class ProjectWorkspaceStateGenerator(
                 Project: {projectSnapshot.FilePath}
                 """);
 
-            return (ProjectWorkspaceState.Create(tagHelpers, csharpLanguageVersion), configuration);
+            return (ProjectWorkspaceState.Create(tagHelpers), configuration);
         }
         catch (OperationCanceledException)
         {

src/Razor/src/Microsoft.VisualStudio.LegacyEditor.Razor/EphemeralProjectSnapshot.cs

@@ -50,7 +50,7 @@ internal class EphemeralProjectSnapshot : IProjectSnapshot
 
     public VersionStamp Version => VersionStamp.Default;
 
-    public LanguageVersion CSharpLanguageVersion => ProjectWorkspaceState.CSharpLanguageVersion;
+    public LanguageVersion CSharpLanguageVersion => Configuration.CSharpLanguageVersion;
 
     public ValueTask<ImmutableArray<TagHelperDescriptor>> GetTagHelpersAsync(CancellationToken cancellationToken) => new(ProjectWorkspaceState.TagHelpers);
 

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/OpenDocumentGeneratorTest.cs

@@ -9,7 +9,6 @@ using Microsoft.AspNetCore.Razor.ProjectSystem;
 using Microsoft.AspNetCore.Razor.Test.Common.LanguageServer;
 using Microsoft.AspNetCore.Razor.Test.Common.ProjectSystem;
 using Microsoft.AspNetCore.Razor.Test.Common.Workspaces;
-using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Text;
 using Xunit;
@@ -142,8 +141,7 @@ public class OpenDocumentGeneratorTest(ITestOutputHelper testOutput) : LanguageS
             updater.DocumentAdded(_hostProject1.Key, _documents[0], _documents[0].CreateEmptyTextLoader());
 
             // Act
-            updater.ProjectWorkspaceStateChanged(_hostProject1.Key,
-                ProjectWorkspaceState.Create(LanguageVersion.CSharp8));
+            updater.ProjectWorkspaceStateChanged(_hostProject1.Key, ProjectWorkspaceState.Default);
         });
 
         // Assert
@@ -166,8 +164,7 @@ public class OpenDocumentGeneratorTest(ITestOutputHelper testOutput) : LanguageS
             updater.DocumentOpened(_hostProject1.Key, _documents[0].FilePath, SourceText.From(string.Empty));
 
             // Act
-            updater.ProjectWorkspaceStateChanged(_hostProject1.Key,
-                ProjectWorkspaceState.Create(LanguageVersion.CSharp8));
+            updater.ProjectWorkspaceStateChanged(_hostProject1.Key, ProjectWorkspaceState.Default);
         });
 
         // Assert

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/RazorProjectServiceTest.cs

@@ -13,7 +13,6 @@ using Microsoft.AspNetCore.Razor.Test.Common;
 using Microsoft.AspNetCore.Razor.Test.Common.LanguageServer;
 using Microsoft.AspNetCore.Razor.Test.Common.ProjectSystem;
 using Microsoft.CodeAnalysis;
-using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Text;
 using Moq;
@@ -66,7 +65,7 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
             updater.ProjectAdded(hostProject);
         });
 
-        var projectWorkspaceState = ProjectWorkspaceState.Create(LanguageVersion.LatestMajor);
+        var projectWorkspaceState = ProjectWorkspaceState.Default;
 
         // Act
         await _projectInfoListener.UpdatedAsync(new RazorProjectInfo(

src/Razor/test/Microsoft.AspNetCore.Razor.ProjectEngineHost.Test/SerializationTest.cs

@@ -7,7 +7,6 @@ using Microsoft.AspNetCore.Razor.ProjectSystem;
 using Microsoft.AspNetCore.Razor.Serialization;
 using Microsoft.AspNetCore.Razor.Serialization.Json;
 using Microsoft.AspNetCore.Razor.Test.Common;
-using Microsoft.CodeAnalysis.CSharp;
 using Newtonsoft.Json.Linq;
 using Xunit;
 using Xunit.Abstractions;
@@ -26,8 +25,7 @@ public class SerializationTest : ToolingTestBase
 
         _configuration = new(languageVersion, "Custom", [new("TestExtension")]);
         _projectWorkspaceState = ProjectWorkspaceState.Create(
-            tagHelpers: [TagHelperDescriptorBuilder.Create("Test", "TestAssembly").Build()],
-            csharpLanguageVersion: LanguageVersion.LatestMajor);
+            tagHelpers: [TagHelperDescriptorBuilder.Create("Test", "TestAssembly").Build()]);
     }
 
     [Fact]

src/Razor/test/Microsoft.AspNetCore.Razor.ProjectEngineHost.Test/StreamExtensionTests.NetCore.cs

@@ -77,7 +77,7 @@ public class StreamExtensionTests
             .TagMatchingRuleDescriptor(rule => rule.RequireTagName("tag-name"))
             .Build();
 
-        var projectWorkspaceState = ProjectWorkspaceState.Create([tagHelper], CodeAnalysis.CSharp.LanguageVersion.Latest);
+        var projectWorkspaceState = ProjectWorkspaceState.Create([tagHelper]);
 
         var projectInfo = new RazorProjectInfo(
             new ProjectKey("TestProject"),

src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common.Tooling/TestMocks.cs

@@ -116,13 +116,13 @@ internal static class TestMocks
             .Returns(hostProject.RootNamespace);
         mock.SetupGet(x => x.DisplayName)
             .Returns(hostProject.DisplayName);
+        mock.SetupGet(x => x.CSharpLanguageVersion)
+            .Returns(hostProject.Configuration.CSharpLanguageVersion);
 
         if (projectWorkspaceState is not null)
         {
             mock.SetupGet(x => x.ProjectWorkspaceState)
                 .Returns(projectWorkspaceState);
-            mock.SetupGet(x => x.CSharpLanguageVersion)
-                .Returns(projectWorkspaceState.CSharpLanguageVersion);
             mock.Setup(x => x.GetTagHelpersAsync(It.IsAny<CancellationToken>()))
                 .ReturnsAsync(projectWorkspaceState.TagHelpers);
         }

src/Razor/test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/ProjectSystem/ProjectStateGeneratedOutputTest.cs

@@ -8,7 +8,6 @@ using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.ProjectSystem;
 using Microsoft.AspNetCore.Razor.Test.Common;
 using Microsoft.AspNetCore.Razor.Test.Common.Workspaces;
-using Microsoft.CodeAnalysis.CSharp;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -184,30 +183,6 @@ public class ProjectStateGeneratedOutputTest : WorkspaceTestBase
         Assert.Equal(state.ProjectWorkspaceStateVersion, actualInputVersion);
     }
 
-    [Fact]
-    public async Task ProjectWorkspaceStateChange_WithProjectWorkspaceState_CSharpLanguageVersionChange_DoesNotCacheOutput()
-    {
-        // Arrange
-        var csharp8ValidConfiguration = new RazorConfiguration(RazorLanguageVersion.Version_3_0, _hostProject.Configuration.ConfigurationName, _hostProject.Configuration.Extensions);
-        var hostProject = TestProjectData.SomeProject with { Configuration = csharp8ValidConfiguration };
-        var originalWorkspaceState = ProjectWorkspaceState.Create(_someTagHelpers, LanguageVersion.CSharp7);
-        var original =
-            ProjectState.Create(ProjectEngineFactoryProvider, hostProject, originalWorkspaceState)
-            .WithAddedHostDocument(_hostDocument, TestMocks.CreateTextLoader("@DateTime.Now", VersionStamp.Default));
-        var changedWorkspaceState = ProjectWorkspaceState.Create(_someTagHelpers, LanguageVersion.CSharp8);
-
-        var (originalOutput, originalInputVersion) = await GetOutputAsync(original, _hostDocument, DisposalToken);
-
-        // Act
-        var state = original.WithProjectWorkspaceState(changedWorkspaceState);
-
-        // Assert
-        var (actualOutput, actualInputVersion) = await GetOutputAsync(state, _hostDocument, DisposalToken);
-        Assert.NotSame(originalOutput, actualOutput);
-        Assert.NotEqual(originalInputVersion, actualInputVersion);
-        Assert.Equal(state.ProjectWorkspaceStateVersion, actualInputVersion);
-    }
-
     [Fact]
     public async Task ConfigurationChange_DoesNotCacheOutput()
     {

src/Razor/test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/ProjectSystem/ProjectStateTest.cs

@@ -9,7 +9,6 @@ using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.ProjectSystem;
 using Microsoft.AspNetCore.Razor.Test.Common;
 using Microsoft.AspNetCore.Razor.Test.Common.Workspaces;
-using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Text;
 using Xunit;
 using Xunit.Abstractions;
@@ -642,45 +641,6 @@ public class ProjectStateTest : WorkspaceTestBase
         Assert.Equal(TestProjectData.SomeProjectFile1.FilePath, documentFilePath);
     }
 
-    [Fact]
-    public void ProjectState_WithProjectWorkspaceState_Changed()
-    {
-        // Arrange
-        var original = ProjectState.Create(ProjectEngineFactoryProvider, _hostProject, _projectWorkspaceState)
-            .WithAddedHostDocument(_documents[2], DocumentState.EmptyLoader)
-            .WithAddedHostDocument(_documents[1], DocumentState.EmptyLoader);
-
-        // Force init
-        var originalTagHelpers = original.TagHelpers;
-        var originalProjectWorkspaceStateVersion = original.ProjectWorkspaceStateVersion;
-
-        var changed = ProjectWorkspaceState.Create(_projectWorkspaceState.TagHelpers, LanguageVersion.CSharp6);
-
-        // Act
-        var state = original.WithProjectWorkspaceState(changed);
-
-        // Assert
-        Assert.NotEqual(original.Version, state.Version);
-        Assert.Same(changed, state.ProjectWorkspaceState);
-
-        var actualTagHelpers = state.TagHelpers;
-        var actualProjectWorkspaceStateVersion = state.ProjectWorkspaceStateVersion;
-
-        // The C# language version changed, and the tag helpers didn't change
-        Assert.NotSame(original.ProjectEngine, state.ProjectEngine);
-
-        Assert.Equal(originalTagHelpers.Length, actualTagHelpers.Length);
-        for (var i = 0; i < originalTagHelpers.Length; i++)
-        {
-            Assert.Same(originalTagHelpers[i], actualTagHelpers[i]);
-        }
-
-        Assert.NotEqual(originalProjectWorkspaceStateVersion, actualProjectWorkspaceStateVersion);
-
-        Assert.NotSame(original.Documents[_documents[1].FilePath], state.Documents[_documents[1].FilePath]);
-        Assert.NotSame(original.Documents[_documents[2].FilePath], state.Documents[_documents[2].FilePath]);
-    }
-
     [Fact]
     public void ProjectState_WithProjectWorkspaceState_Changed_TagHelpersChanged()
     {
@@ -727,7 +687,7 @@ public class ProjectStateTest : WorkspaceTestBase
         _ = original.TagHelpers;
         _ = original.ProjectWorkspaceStateVersion;
 
-        var changed = ProjectWorkspaceState.Create(original.TagHelpers, original.CSharpLanguageVersion);
+        var changed = ProjectWorkspaceState.Create(original.TagHelpers);
 
         // Act
         var state = original.WithProjectWorkspaceState(changed);

src/Shared/Microsoft.AspNetCore.Razor.Serialization.Json/ObjectReaders.cs

@@ -45,6 +45,7 @@ internal static partial class ObjectReaders
         var suppressAddComponentParameter = reader.ReadBooleanOrFalse(nameof(RazorConfiguration.SuppressAddComponentParameter));
         var useConsolidatedMvcViews = reader.ReadBooleanOrTrue(nameof(RazorConfiguration.UseConsolidatedMvcViews));
         var useRoslynTokenizer = reader.ReadBooleanOrFalse(nameof(RazorConfiguration.UseRoslynTokenizer));
+        var csharpLanguageVersion = (LanguageVersion)reader.ReadInt32OrZero(nameof(RazorConfiguration.CSharpLanguageVersion));
         var extensions = reader.ReadImmutableArrayOrEmpty(nameof(RazorConfiguration.Extensions),
             static r =>
             {
@@ -103,9 +104,8 @@ internal static partial class ObjectReaders
     public static ProjectWorkspaceState ReadProjectWorkspaceStateFromProperties(JsonDataReader reader)
     {
         var tagHelpers = reader.ReadImmutableArrayOrEmpty(nameof(ProjectWorkspaceState.TagHelpers), static r => ReadTagHelper(r, useCache: true));
-        var csharpLanguageVersion = (LanguageVersion)reader.ReadInt32OrZero(nameof(ProjectWorkspaceState.CSharpLanguageVersion));
 
-        return ProjectWorkspaceState.Create(tagHelpers, csharpLanguageVersion);
+        return ProjectWorkspaceState.Create(tagHelpers);
     }
 
     public static TagHelperDescriptor ReadTagHelper(JsonDataReader reader, bool useCache)

src/Shared/Microsoft.AspNetCore.Razor.Serialization.Json/ObjectWriters.cs

@@ -38,6 +38,7 @@ internal static class ObjectWriters
         writer.WriteIfNotFalse(nameof(value.SuppressAddComponentParameter), value.SuppressAddComponentParameter);
         writer.WriteIfNotTrue(nameof(value.UseConsolidatedMvcViews), value.UseConsolidatedMvcViews);
         writer.WriteIfNotFalse(nameof(value.UseRoslynTokenizer), value.UseRoslynTokenizer);
+        writer.WriteIfNotZero(nameof(value.CSharpLanguageVersion), (int)value.CSharpLanguageVersion);
 
         writer.WriteArrayIfNotNullOrEmpty(nameof(value.Extensions), value.Extensions, static (w, v) => w.Write(v.ExtensionName));
     }